Merge branch 'master' into java9

.gitignore

@@ -17,3 +17,4 @@ datanucleus.log
 /bin/
 *.log
 data-mapper/src/main/resources/log4j.xml
+event-sourcing/Journal.json

.travis.yml

@@ -36,4 +36,4 @@ notifications:
     on_failure: always  # options: [always|never|change] default: always
     on_start: never     # options: [always|never|change] default: always
 
-sudo: false # route the build to the container-based infrastructure for a faster build
+sudo: required

_scripts/postPumlsToServer.firstrun.output

@@ -1,190 +0,0 @@
-parent: half-sync-half-async; artifact: half-sync-half-async
-Puml Server ID: RScv3SCm3030LU819FRPXg5fIm552tnYPFiyjRi3RkbAaYkdoQr5JBy369vrxz7oaSv6XmPhL3e6TCaJ0msU-CAoilTToyG8DdKOw5z0GzcAlvNAN_WZSD1brBHHPmxv0000
-parent: abstract-document; artifact: abstract-document
-Puml Server ID: PSjB3eCm34NHhPG599vtDyQn85L-ifzX-p3lxEf8Twj3MXGDQvyJMFubChxpKN767gucSq07iinEjSNDOACVNvoAUZr6MWoe3QVE_WRnxZ0Mf38b-hkIGlurX_MyehS7
-parent: tolerant-reader; artifact: tolerant-reader
-Puml Server ID: NSZ14SCm20NHLf829ExfXaYChGn26lZ4xSVdtFRjSrZJx9AkZnFOyI9olkenSEOxGxmjWnXgMvE6viLWfmz_kNI9SLZP38XRqEIuWx1Kd0t5XVjjGVj_DNtMdLD_
-parent: event-driven-architecture; artifact: event-driven-architecture
-Puml Server ID: TOhH3SCW30LNQGS0_tSRnrZ15H1adfFromBzkfFktZQaHT7mzgh0N1yYvoUVXXf7B7Mv1dGWozN9MZmCTlhopQdeidEaoO3wMDHvRI6zzvwAssPYbsfGGRYIGlxN7DxpZDv-
-parent: publish-subscribe; artifact: publish-subscribe
-Puml Server ID: PSZB3SCm203GLTe1RExT1XCKKs5YyMdMR--zFRsd66aTNAwFcRdZ1U1uzrDorgXWfykIBJjT2qJhnaI7Dtwm7HnoMjkOoMu12-C7s3LKOhQe4UGo63ZfVtlvwhkMVW40
-parent: facade; artifact: facade
-Puml Server ID: BSP15eCm20N0gxG7CEoz3ILKqvTW7dpq-hhehERTJ7fMJU-l7PYn4ZbVPMlOyvEXBeT13KMEGQtdnM2d7v-yL8sssJ8PKBUWmV64lYnSbHJoRqaVPUReDm00
-parent: service-locator; artifact: service-locator
-Puml Server ID: NSjB3iCm203HgxG7iDdtDeIWX0fZYqzo_MRTtUX9ynOZhPtBzNLchlW0EDxza3nhgs2dQScMdUO0qRenqU6B5xQTGmvh2pFPBM1WF07FSmbnqqcOqu6J_gsNZxvgw0y0
-parent: dao; artifact: dao
-Puml Server ID: 5SR14OKW30N0LhG0oVrt4o6ZE12Ov4NR_thQNQlc5aN2sd82qtz4naywAixOmyNoK8WYvT6fjdWOR7JnpLiHhuTkam4nTUhiRwZm847-J64zpUZj3m00
-parent: model-view-presenter; artifact: model-view-presenter
-Puml Server ID: ROlR3SGW3C1MkGu0-RzjKeXQJWcWFChwPO3xispvQBrmL0hbp-q-xGkWkFBL_8upZBICxjGzbo7GE1OwAlpmmLJ9sjNJH7VIRY1e6q169KvFevMcakrtI_BoD-HGoJE4Nm00
-parent: observer; artifact: observer
-Puml Server ID: FSkn4OGm30NHLg00hFow4KO3PcpP8tr1-pYwx6smQz5Suv2mkbp0y1-HyPlEWYlsSB7S5Q98kJSgDLu66ztyy7Q8brEtmO2OEZNs2Uhxl9u9GVv72cjfHAiV
-parent: intercepting-filter; artifact: intercepting-filter
-Puml Server ID: RSfB3i8m303Hgy014k-vZN5DQkIuaJ_q-fGzkz7JtCL8Q-DolUsPAnu0ZcSVadizAzZfi6JBJiS4qJenqU6D7smRXmnh2pFPBM1YN05o_KwyKcoqb-ZFEEcVz_BPLqtz0W00
-parent: factory-method; artifact: factory-method
-Puml Server ID: NSZB3G8n30N0Lg20n7UwCOxPP9MVx6TMT0zdRgEvjoazYeRrMmMsFuYChtmqr7Y6gycQq8aiQr3hSJ7OwEGtfwBUZfas0shJQR3_G2yMBFkaeQYha4B-AeUDl6FqBm00
-parent: private-class-data; artifact: private-class-data
-Puml Server ID: RShR3SCm243HLTe1RFwx3S4eeSB4uf6itmpGlwkZ-nOZhS7b-ZeoLtm07E--InwrLR3JQScMdSu9edLZeiCNBso3GtPh2pFPBM1YF07BvSBaHeeHRJm_SD8VxkMphvhw0m00
-parent: async-method-invocation; artifact: async-method-invocation
-Puml Server ID: TSdB3SCW303GLTe1mFTkunWhk0A3_4dKxTi5UdlIUuhIoCPfuz4Zjhy03EzwIlGyqjbeQR16fJL1HjuOQF362qjZbrFBnWWsTPZeFm3wHwbCZhvQ4RqMOSXIuA1_LzDctJd75m00
-parent: execute-around; artifact: execute-around
-Puml Server ID: NSZ14G8n20NGLhI0XBlT865suoGa0n_NylNixSsxTvEHJTF7xGHsF8YShtfqdFdCK9TbK4ELDQcFl1ZizE8tbwRH3okR0NKBcXm_a7vK4bhOLreZXVnLJPzrvnnV
-parent: monostate; artifact: monostate
-Puml Server ID: HSV14OGm20NGLjO23FVj1YEZsGaa0nzjVxrvUszfLdlkaju_9p3ZI-HybwFXp2r3l0w364eTIgtdpM2d7r-yxXBji7Ko86v1ol60TDW8C8G4zLr9rp9J-ny0
-parent: thread-pool; artifact: thread-pool
-Puml Server ID: JSV14SCW30J0Lk82GFzq8uF6a1624IUx_UIPt-xHhMXK2TTN0zP-4pa_-UfeSSOMBzCWXbpceAxnCDZfmpUdAhjVbXO3uhPfyFw1q5oufZMdag3yFuUFl6Be5m00
-parent: delegation; artifact: delegation
-Puml Server ID: JSV14GCX20NGLf82LkxfXbN69OFeu2VRVdBCxRsdUhLiac6F2rZxHHHybwwuyimjKQT37ANEGMfvCpZepHy-ccpjVYm697pJuFq3DJ7f39rEWlhNaZ7Aoc5V
-parent: chain; artifact: chain
-Puml Server ID: 9SR13SCm20NGLTe1OkxTXX0KKzd4Wa-pVYlrdTxJN4OTMZ4U7LZv8Wg-ssdejLTgoELGHvDhaesw6HpqvWzlXwQTlYq6D3nfSlv2qjcS5F9VgvXjrHnV
-parent: resource-acquisition-is-initialization; artifact: resource-acquisition-is-initialization
-Puml Server ID: ZShR3S8m343HLUW0YV_PnhXMQvGumOzMOdhA1lqxkhgBABLSEQqzzeZfJm33isuIUxxIsMXei4QbqK5QdXXeyCO3oyekcvQ94MpgqD4lWB6FDEA2z4bn2HbQn8leHMponNy13hgvrhHUP_Rs0m00
-parent: fluentinterface; artifact: fluentinterface
-Puml Server ID: NOj93eCm302_KXv0VEzlN6F0bMCYB_3zvjpRQ3IpY97MnkNwEZD7l04SdtP8dlMfOAVBaYqRNHr4wy54Xo_Uk6uSSjWwC9FT0Zh61DYrPY_pyXs9WPF-NIllRLJN7m00
-parent: service-layer; artifact: service-layer
-Puml Server ID: LOl93SCm3C1MQGUmzUysgY8aAcJ5q96WszVV_aW2V8gHriRb-ZWoPxm07E--Inxrhc2dqv8jEvq3HEl6H8SFNjWs3jcjJSnaju21iG3MSmbnK_mkuwJ_qij7dpNq1m00
-parent: visitor; artifact: visitor
-Puml Server ID: DSR14OGm20NGLhG0mtsxmSWeJa8oyD7sTo_xJczLgoqFIM_B1Spu43c_vLHSkMU8rs4GGwcZaxPy6UnqyyFR8Q6dRPC1SGlg7B_Gew4OJeBwVqdlPMPlNm00
-parent: double-dispatch; artifact: double-dispatch
-Puml Server ID: NSbB3iCW303HgpG70Ezx6yTOWSeOv4zp_MRTtUZDCPGa6wV9gqTiVmCOtlKQqVDCPwEbmHgLreGXUMEWmGU_M1hxkBHiZ61JXud-1BILft1fmvz37JZetshQh3kd_000
-parent: monad; artifact: monad
-Puml Server ID: 9SR13SCm20NGLPe1OkxTXjWeSMMm1Pza_LRgExsjMntP97syBc35cyZvAMV7bKU6U9q6CPGwbVh8Xy5E7xvvRnBzj7qn86v1ol4BwJHk9AZ_bNGjAtLy0G00
-parent: front-controller; artifact: front-controller
-Puml Server ID: PSlB3OGm303HLfO24j-t6nCC13bEvC_IFk6yjz6JPgbIE3OAvS_fFkmBe7Zde_ePQnXfwU8adajlK3bkT5Iuy8Tf8wk7f87kf6BGq6R0hlD8xwQTUG9v-SCSslA8nWy0
-parent: strategy; artifact: strategy
-Puml Server ID: FSV13OCm30NGLM00udktCS4AGOaJsTz5tRwSkBstLiqj3WbhombC_n0PtwbKdB67Y-MX44NAerDjSJFOwE8lRuTuBRfD1iJKgRC_88SnfFn8aD-ai9vczFO7
-parent: command; artifact: command
-Puml Server ID: DSgn4OCm30NGLM00h3xR25i7vYpXaxx2-g59zugtTgiZcwIFvGHcV8YSdt9qdBbdYDVR88PIRwK-yc6mqyLVtff4FsoR38XRa7Aye3SgMoD1_RkaQvcfumS0
-parent: abstract-factory; artifact: abstract-factory
-Puml Server ID: PSZB3OD034NHLa81Czwd6sCC39gVxEUWT1_ssLmTtQLqgR5fM7sTmFGtaV6TZu8prd0r6HtQaMKqAZLk1XjT_E6qgPUZfyc0MdTgx0-8LuUn8ErFXdr98NypXxKyezKV
-parent: flux; artifact: flux
-Puml Server ID: 7SP14eCm20NGg-W13FlU1YFLE0GpyAazVZk-rPkRLSrDqdKwW14l8kUxx0r7hXdYzJA8eTIhKzEy6UnqyeUNJQBjjWm6n2seS_n3Ryql2UgJajxBoAu_
-parent: event-aggregator; artifact: event-aggregator
-Puml Server ID: PSf13iCW30NHgxG70Ezx6uTOX0eCih-JwvTzTwEdUJSjFKu9wwyBMFuXCdvoRRZY21ShKo6ANEQWrkDXiD6NRqwdUAkQ5WDYwZJOTv3SUqzSgqbbp0qeVvZ3Hbun-Wy0
-parent: singleton; artifact: singleton
-Puml Server ID: HSV14SCm20J0Lk82BFxf1ikCh0n26ZZizfDVVhjRjwfvIhg-Bc35cyZvAQtZoYD3l4w364gTWxhcms2d3z-ydnAzsRuO4BUWmV43HRUcWcaagF-Lz55M3lq2
-parent: null-object; artifact: null-object
-Puml Server ID: JSV14SCm20J0Lk829Fxf1cF6bWSX3JhYzfDdVhjRSx4yDCDU5p3NcoZugMV3bNik3HaETLGPdPhbm-2WcpzS3btjz38PqF15dTSFv6bMndwhW1Jo_vhHwynkNm00
-parent: multiton; artifact: multiton
-Puml Server ID: FST14i8m20NGg-W16lRUXgPCYnD81Zxs-hfozzvJlOywf68yBc3bYoZuRgVYghrIea-7E5gVHZhgPd3Gcp-y7P9w-hOOaF0au_o1h0OKqqdG_saLrbRP-080
-parent: composite; artifact: composite
-Puml Server ID: HSf13eCm30NHgy01YFUzZGaM62LEP7-NwvTTT_EaMTLgoqFIst81Cpv4payv5LVk6U9r6CHGwkYaBHy6EztyvUsGqDEsoO2u1NMED-WTvmY5aA3-LT9xcTdR3m00
-parent: api-gateway; artifact: image-microservice
-Puml Server ID: 3Sp13SCm2030LTe1RFxTXX3aK1biOOZLxPlVlUujHZrFJk-lAsAk3u3ZhatYoYCNEmqBjgWq5AJdna27BzvOJbxIh4oCOBS5Yki1u9JIC7ZZ3pW8HB5nKI4VJtSBSKtNEbFx7m00
-I dont want to program this, just add the following lines to the README.md file that corresponds to this puml file 'api-gateway/etc/image-microservice.urm.puml'
-pumlid: 3Sp13SCm2030LTe1RFxTXX3aK1biOOZLxPlVlUujHZrFJk-lAsAk3u3ZhatYoYCNEmqBjgWq5AJdna27BzvOJbxIh4oCOBS5Yki1u9JIC7ZZ3pW8HB5nKI4VJtSBSKtNEbFx7m00
-parent: api-gateway; artifact: api-gateway-service
-Puml Server ID: JSox3SCm303HLP819FRUXg49cO542_nOyFPncUvUSszHwhbpMdyT4TCt0CDLcyIHdtGsEZLOez8vG7ek33JuueLbPvUcPM84cpeCz2S0fvI6mGjluA1_b-Tt2N5D6tNcw3y0
-I dont want to program this, just add the following lines to the README.md file that corresponds to this puml file 'api-gateway/etc/api-gateway-service.urm.puml'
-pumlid: JSox3SCm303HLP819FRUXg49cO542_nOyFPncUvUSszHwhbpMdyT4TCt0CDLcyIHdtGsEZLOez8vG7ek33JuueLbPvUcPM84cpeCz2S0fvI6mGjluA1_b-Tt2N5D6tNcw3y0
-parent: api-gateway; artifact: price-microservice
-Puml Server ID: 3Sn13iGW243HgqmFeEpdDfGIoqJK8DJqzkFklyq_f56DYyFgvtOVymjWk78Hl-ECoKQzEJVFr1Mana97Wny-c2wUKbeQwCxM9YZE7O13Ka7dXI-m4mmJugH2rlVksSXXcaTe_GC0
-I dont want to program this, just add the following lines to the README.md file that corresponds to this puml file 'api-gateway/etc/price-microservice.urm.puml'
-pumlid: 3Sn13iGW243HgqmFeEpdDfGIoqJK8DJqzkFklyq_f56DYyFgvtOVymjWk78Hl-ECoKQzEJVFr1Mana97Wny-c2wUKbeQwCxM9YZE7O13Ka7dXI-m4mmJugH2rlVksSXXcaTe_GC0
-parent: object-pool; artifact: object-pool
-Puml Server ID: JSV94SCm2030Lk829Fxf1cF6bWU1XYDkFtdcjxiD9Qc3o-LrPQvu0pW-_HnvrLx1JgR9cfrimf1wCD7XnW-sWsESsXPcicl0nFW1RB-PiYqp0KxwVo-VVTMKBm00
-parent: adapter; artifact: adapter
-Puml Server ID: DSR14S8m30J0Lg20M7-wEMnDOiPMFDA9j0yyUEtUkzMHJTF7xI1NF4GSLzaxZtncgDVJgCPIpobzv0N2vOKtjgRHTziMI7KBcOXl10thfxB-Nz9dMJd71m00
-parent: hexagonal; artifact: hexagonal
-Puml Server ID: HSTB4W8X30N0g-W1XkozpPD90LO8L3wEnzUTk-xxq2fvSfhSUiJs1v7XAcr4psSwMrqQh57gcZGaBmICNdZZEDb7qsCZWasT9lm7wln1MmeXZlfVIPjbvvGl
-parent: value-object; artifact: value-object
-Puml Server ID: LSZ13SCm20NGLTe1RExTXX2KECBOmfza_VRQszDxDnVBNJFiTG9pVOY2dteqdBdbqf3XK4ULqQbPFWmEklZcikjgXvV9W8Olwhn-e9ijjOpjKW4fv2zgHgypktq1
-parent: twin; artifact: twin
-Puml Server ID: 7SR13OCm30NGLUW0n7UsCS42eyH4zdUpFbNVwNtKQij3qjjo0ICs8kTPJiMLUuPuVGnYAFNff2qdWvrk_l9wIEXfws10t88wno-4gKQ2-az9xsLaRoy0
-parent: semaphore; artifact: semaphore
-Puml Server ID: HSV14SCm20J0Lk82BFxf1ikCfOn06ZZizfDVVhjRjphobFJnQi2ADv7pKwwEbaU6U9q6CPGwbVh8Xy5E7xvvFoNwPVjYGDo2bEC72b5URRgGeFvNqhMirF45
-parent: message-channel; artifact: message-channel
-Puml Server ID: NSZB3SCm203GLTe1RExTXX1akm9YyMdMRy-zFRtdCf8wkLmUCtF72y3nxcFbhAE2dIvBjknqAIof6nCTtlZ1TdAiOMrZ9hi5ACOFe1o1WnjDD6C1Jlg_NgvzbyeN
-parent: poison-pill; artifact: poison-pill
-Puml Server ID: JSZ14SCm20NHLf82BExfXiYCJGOX3NpYzkDZRllsgTwjTgcmnmciV145N-rGdFMkbEZJ8OxMvo2rkXWSzE4lRxka7huj1YGyQN3UGMjgpdkh6Gdwlrl5QAk6_G00
-parent: aggregator-microservices; artifact: aggregator-service
-Puml Server ID: JOov3SCm301NIGQGs7iRXYPa1g8ayB7NjuiKwGvtmBrbKC-Tq_hhY5Y-0HXUjKaS-Kbdepc2HrIQ2jBpma23BvvOTdPfeooCO1iEYlu0O6l63MDQKI6Rp-CKOWSE-ey_NzEqhjH-0m00
-I dont want to program this, just add the following lines to the README.md file that corresponds to this puml file 'aggregator-microservices/etc/aggregator-service.urm.puml'
-pumlid: JOov3SCm301NIGQGs7iRXYPa1g8ayB7NjuiKwGvtmBrbKC-Tq_hhY5Y-0HXUjKaS-Kbdepc2HrIQ2jBpma23BvvOTdPfeooCO1iEYlu0O6l63MDQKI6Rp-CKOWSE-ey_NzEqhjH-0m00
-parent: aggregator-microservices; artifact: information-microservice
-Puml Server ID: LSnB3i8m303Hgy016k-vZN5DQXGxaJ_jzUcMtKXFcgSOZTgvV3oEp1Kl0CUhTScZtXNiD2tPij5Ka54N9ZfyySHjvv1ksy9CTWjGZ3i0UtVkcDCt5V9vFquX3k0a4FjCLqoPzgUjNDig7Jy0
-I dont want to program this, just add the following lines to the README.md file that corresponds to this puml file 'aggregator-microservices/etc/information-microservice.urm.puml'
-pumlid: LSnB3i8m303Hgy016k-vZN5DQXGxaJ_jzUcMtKXFcgSOZTgvV3oEp1Kl0CUhTScZtXNiD2tPij5Ka54N9ZfyySHjvv1ksy9CTWjGZ3i0UtVkcDCt5V9vFquX3k0a4FjCLqoPzgUjNDig7Jy0
-parent: aggregator-microservices; artifact: inventory-microservice
-Puml Server ID: LSpB3G8n303HLg20ZUzqOxnMrYXn8d-oedjovJRIIEyfIYrFJckFAsBw2y3mBbNYodSw6mqDrYWqEaZB6mCDFhZmEDcbwZ4nWaqTEleEm5gDAyQmemlPsCOIOWSE0j6riM7VlrVIUfdPsmy0
-I dont want to program this, just add the following lines to the README.md file that corresponds to this puml file 'aggregator-microservices/etc/inventory-microservice.urm.puml'
-pumlid: LSpB3G8n303HLg20ZUzqOxnMrYXn8d-oedjovJRIIEyfIYrFJckFAsBw2y3mBbNYodSw6mqDrYWqEaZB6mCDFhZmEDcbwZ4nWaqTEleEm5gDAyQmemlPsCOIOWSE0j6riM7VlrVIUfdPsmy0
-parent: bridge; artifact: bridge
-Puml Server ID: BSR14SCm20J0Lf82BFxf1akCJ4R26ZZYzkE7zxLljJgoIVfu7S2A3v7pLRhYo3r3l9u6CPHwJjAH5uETllpZhKbejsqn86v1a-CExQwj2mdgqv8-oyev_W00
-parent: servant; artifact: servant
-Puml Server ID: DSkn4O0m20NGLNG0G-ys63cDbv0SV7HzRUnUy-QYkSOkONKwWU4haV6JZe8pjd2nt1MYIBatAZKU1XjTVFEoYvT3by60c3erzW_qdPiL9CY_KrXB8rfz0G00
-parent: lazy-loading; artifact: lazy-loading
-Puml Server ID: LSXB3W8X303Gg-W1e7jlqu66gIc5zED4JwzRTo_lpjeaEwN9xOpO_W0mlEhWEFD89sjBWpHgMnDOyi90WoU-i7Ho7besHf2fmqJ_0GG_xo8BE-i0YlONDMtMdLE-
-parent: flyweight; artifact: flyweight
-Puml Server ID: HSV94S8m3030Lg20M7-w4OvYAoCh7Xtnq3ty-Eq-MQlaJcdow17JNm26gpIEdkzqidffa4Qfrm2MN1XeSEADsqxEJRU94MJgCD1_W4C-YxZr08hwNqaRPUQGBm00
-parent: mutex; artifact: mutex
-Puml Server ID: 9SR13OCm30NGLSe0n7UsCS62LB69x6zWV2hrdTxKhFRS9Br_3c34GkHybxtXo3L3l9u6CPHwAhMUDuETldpnl4cqtUR1WBW5ASSlf0bvI53_A-bQHcf_0G00
-parent: mediator; artifact: mediator
-Puml Server ID: FSV14SCm20J0Lk82BFxf1akCJKOW3JhizfDNVhkRUktP9AE_Bc2kDr7mKqx5bKSkYJeSuYXr66dFXy517xvvRxBqz7qo8E6BZDSFPDAKCO84zP-IOMMczIy0
-parent: page-object; artifact: page-object
-Puml Server ID: JSV14OGW30NGLjO28FVj9iOCua1Wme-sxnxtzjvMJLeS6ju-9p3NbyZvoQNYZ3sMkWo36hACJhN5ms2dYszEXwvQB4q6r6rHv_K3JIwQndwfW1Jo_npUyupUNW00
-parent: factory-kit; artifact: factory-kit
-Puml Server ID: JST15i8m20N0g-W14lRU1YcsQ4BooCS-RwzBTpDNSscvQKQx7C1SDwBWi-w68--vD6Gur55bTBAM9uE3dlpcikcotSjaGCCNTLu_q8C58pxbPI25_Bzcz3gpjoy0
-parent: property; artifact: property
-Puml Server ID: FSV13OCm30NGLTe1YEziumOBKYMEPN-3s9wUUdlltRJst2Izlmx0OYLolihUSEGdGxnEXIXAdODQpul1Jby-UTaasgwBCI2kGOFZ1pAV9ewR1FMVaZwAvUWF
-parent: dependency-injection; artifact: dependency-injection
-Puml Server ID: RSdB3SCW303GLPe1mFTkunWhSGG6-PEesxS3zFQajubIpyPf_NL6B7y363xra3XpJsUZgS4QbUO0wVbWeC65DvR6BeUMXH5iwZ3GVu36YxMnqgU8NamXKu63_aPD6tNbw5y0
-parent: layers; artifact: layers
-Puml Server ID: BSR13OCm30NGLSe0n7UsCS62L8w9x6yGszD3t-bDpQhc9kdwEO0H2v7pNVQ68zSCyNeQn53gsQbftWns-lB5yoRHTfi70-8Mr3b-8UL7F4XG_otflOpi-W80
-parent: producer-consumer; artifact: producer-consumer
-Puml Server ID: PSjB3iCW303HgxG70Ezx6zTO2HKso9_a-c7VtUX9y-vA8nkdZTSPiVm3O7ZNeyUPttGscXgiKMaAz94t1XhyyCBIsFkXPM44cpe8-WvODbiIMzcdfspXe7-jQL9NodW0
-parent: builder; artifact: builder
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-I dont want to program this, just add the following lines to the README.md file that corresponds to this puml file 'naked-objects/etc/naked-objects-dom.urm.puml'
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-I dont want to program this, just add the following lines to the README.md file that corresponds to this puml file 'naked-objects/etc/naked-objects-fixture.urm.puml'
-pumlid: LSX15i8W30N0g-W187jlaq9igH1uoO_r-BfrDs_kJKkFAc7zTW3B7qJ6LzuRZjZ2nSfKY2ANEQZrk1XiTFARKnLlkwR5W9Ww3VOVIFabDStjb08dGVcVz6mVX4aE6td5w5y0
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abstract-factory/README.md

@@ -18,7 +18,107 @@ Kit
 Provide an interface for creating families of related or dependent
 objects without specifying their concrete classes.
 
-![alt text](./etc/abstract-factory_1.png "Abstract Factory")
+## Explanation
+Real world example
+
+> To create a kingdom we need objects with common theme. Elven kingdom needs an Elven king, Elven castle and Elven army whereas Orcish kingdom needs an Orcish king, Orcish castle and Orcish army. There is a dependency between the objects in the kingdom.
+
+In plain words
+
+> A factory of factories; a factory that groups the individual but related/dependent factories together without specifying their concrete classes.
+
+Wikipedia says
+
+> The abstract factory pattern provides a way to encapsulate a group of individual factories that have a common theme without specifying their concrete classes
+
+**Programmatic Example**
+
+Translating the kingdom example above. First of all we have some interfaces and implementation for the objects in the kingdom
+
+```
+public interface Castle {
+  String getDescription();
+}
+public interface King {
+  String getDescription();
+}
+public interface Army {
+  String getDescription();
+}
+
+// Elven implementations ->
+public class ElfCastle implements Castle {
+  static final String DESCRIPTION = "This is the Elven castle!";
+  @Override
+  public String getDescription() {
+    return DESCRIPTION;
+  }
+}
+public class ElfKing implements King {
+  static final String DESCRIPTION = "This is the Elven king!";
+  @Override
+  public String getDescription() {
+    return DESCRIPTION;
+  }
+}
+public class ElfArmy implements Army {
+  static final String DESCRIPTION = "This is the Elven Army!";
+  @Override
+  public String getDescription() {
+    return DESCRIPTION;
+  }
+}
+
+// Orcish implementations similarly...
+
+```
+
+Then we have the abstraction and implementations for the kingdom factory
+
+```
+public interface KingdomFactory {
+  Castle createCastle();
+  King createKing();
+  Army createArmy();
+}
+
+public class ElfKingdomFactory implements KingdomFactory {
+  public Castle createCastle() {
+    return new ElfCastle();
+  }
+  public King createKing() {
+    return new ElfKing();
+  }
+  public Army createArmy() {
+    return new ElfArmy();
+  }
+}
+
+public class OrcKingdomFactory implements KingdomFactory {
+  public Castle createCastle() {
+    return new OrcCastle();
+  }
+  public King createKing() {
+    return new OrcKing();
+  }
+  public Army createArmy() {
+    return new OrcArmy();
+  }
+}
+```
+
+Now we have our abstract factory that lets us make family of related objects i.e. Elven kingdom factory creates Elven castle, king and army etc.
+
+```
+KingdomFactory factory = new ElfKingdomFactory();
+Castle castle = factory.createCastle();
+King king = factory.createKing();
+Army army = factory.createArmy();
+
+castle.getDescription();  // Output: This is the Elven castle!
+king.getDescription(); // Output: This is the Elven king!
+army.getDescription(); // Output: This is the Elven Army!
+```
 
 ## Applicability
 Use the Abstract Factory pattern when
@@ -41,9 +141,6 @@ Use the Abstract Factory pattern when
 
 *	Dependency injection in java hides the service class dependencies that can lead to runtime errors that would have been caught at compile time.
 
-
-
-
 ## Real world examples
 
 * [javax.xml.parsers.DocumentBuilderFactory](http://docs.oracle.com/javase/8/docs/api/javax/xml/parsers/DocumentBuilderFactory.html)

abstract-factory/etc/abstract-factory.ucls

@@ -1,159 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<class-diagram version="1.1.8" icons="true" automaticImage="PNG" always-add-relationships="false" generalizations="true" 
-  realizations="true" associations="true" dependencies="false" nesting-relationships="true">  
-  <interface id="1" language="java" name="com.iluwatar.abstractfactory.Army" project="abstract-factory" 
-    file="/abstract-factory/src/main/java/com/iluwatar/abstractfactory/Army.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="70" width="161" x="1407" y="300"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </interface>  
-  <interface id="2" language="java" name="com.iluwatar.abstractfactory.KingdomFactory" project="abstract-factory" 
-    file="/abstract-factory/src/main/java/com/iluwatar/abstractfactory/KingdomFactory.java" binary="false" 
-    corner="BOTTOM_RIGHT">    
-    <position height="124" width="161" x="1001" y="300"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </interface>  
-  <class id="3" language="java" name="com.iluwatar.abstractfactory.ElfCastle" project="abstract-factory" 
-    file="/abstract-factory/src/main/java/com/iluwatar/abstractfactory/ElfCastle.java" binary="false" 
-    corner="BOTTOM_RIGHT">    
-    <position height="106" width="161" x="96" y="118"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </class>  
-  <class id="4" language="java" name="com.iluwatar.abstractfactory.ElfKingdomFactory" project="abstract-factory" 
-    file="/abstract-factory/src/main/java/com/iluwatar/abstractfactory/ElfKingdomFactory.java" binary="false" 
-    corner="BOTTOM_RIGHT">    
-    <position height="142" width="161" x="900" y="118"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </class>  
-  <class id="5" language="java" name="com.iluwatar.abstractfactory.ElfKing" project="abstract-factory" 
-    file="/abstract-factory/src/main/java/com/iluwatar/abstractfactory/ElfKing.java" binary="false" 
-    corner="BOTTOM_RIGHT">    
-    <position height="106" width="161" x="498" y="118"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </class>  
-  <interface id="6" language="java" name="com.iluwatar.abstractfactory.King" project="abstract-factory" 
-    file="/abstract-factory/src/main/java/com/iluwatar/abstractfactory/King.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="70" width="161" x="599" y="300"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </interface>  
-  <class id="7" language="java" name="com.iluwatar.abstractfactory.OrcCastle" project="abstract-factory" 
-    file="/abstract-factory/src/main/java/com/iluwatar/abstractfactory/OrcCastle.java" binary="false" 
-    corner="BOTTOM_RIGHT">    
-    <position height="106" width="161" x="297" y="118"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </class>  
-  <class id="8" language="java" name="com.iluwatar.abstractfactory.OrcKing" project="abstract-factory" 
-    file="/abstract-factory/src/main/java/com/iluwatar/abstractfactory/OrcKing.java" binary="false" 
-    corner="BOTTOM_RIGHT">    
-    <position height="106" width="161" x="699" y="118"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </class>  
-  <class id="9" language="java" name="com.iluwatar.abstractfactory.ElfArmy" project="abstract-factory" 
-    file="/abstract-factory/src/main/java/com/iluwatar/abstractfactory/ElfArmy.java" binary="false" 
-    corner="BOTTOM_RIGHT">    
-    <position height="106" width="161" x="1306" y="118"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </class>  
-  <class id="10" language="java" name="com.iluwatar.abstractfactory.OrcArmy" project="abstract-factory" 
-    file="/abstract-factory/src/main/java/com/iluwatar/abstractfactory/OrcArmy.java" binary="false" 
-    corner="BOTTOM_RIGHT">    
-    <position height="106" width="161" x="1507" y="118"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </class>  
-  <interface id="11" language="java" name="com.iluwatar.abstractfactory.Castle" project="abstract-factory" 
-    file="/abstract-factory/src/main/java/com/iluwatar/abstractfactory/Castle.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="70" width="161" x="197" y="300"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </interface>  
-  <class id="12" language="java" name="com.iluwatar.abstractfactory.OrcKingdomFactory" project="abstract-factory" 
-    file="/abstract-factory/src/main/java/com/iluwatar/abstractfactory/OrcKingdomFactory.java" binary="false" 
-    corner="BOTTOM_RIGHT">    
-    <position height="142" width="165" x="1101" y="118"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </class>  
-  <realization id="13">    
-    <end type="SOURCE" refId="4"/>    
-    <end type="TARGET" refId="2"/>  
-  </realization>  
-  <realization id="14">    
-    <end type="SOURCE" refId="7"/>    
-    <end type="TARGET" refId="11"/>  
-  </realization>  
-  <realization id="15">    
-    <end type="SOURCE" refId="8"/>    
-    <end type="TARGET" refId="6"/>  
-  </realization>  
-  <realization id="16">    
-    <end type="SOURCE" refId="3"/>    
-    <end type="TARGET" refId="11"/>  
-  </realization>  
-  <realization id="17">    
-    <end type="SOURCE" refId="10"/>    
-    <end type="TARGET" refId="1"/>  
-  </realization>  
-  <realization id="18">    
-    <end type="SOURCE" refId="12"/>    
-    <end type="TARGET" refId="2"/>  
-  </realization>  
-  <realization id="19">    
-    <end type="SOURCE" refId="5"/>    
-    <end type="TARGET" refId="6"/>  
-  </realization>  
-  <realization id="20">    
-    <end type="SOURCE" refId="9"/>    
-    <end type="TARGET" refId="1"/>  
-  </realization>  
-  <classifier-display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-    sort-features="false" accessors="true" visibility="true">    
-    <attributes public="true" package="true" protected="true" private="true" static="true"/>    
-    <operations public="true" package="true" protected="true" private="true" static="true"/>  
-  </classifier-display>  
-  <association-display labels="true" multiplicity="true"/>
-</class-diagram>

abstract-factory/etc/abstract-factory.urm.puml

@@ -1,89 +0,0 @@
-@startuml
-package com.iluwatar.abstractfactory {
-  class App {
-    - LOGGER : Logger {static}
-    - army : Army
-    - castle : Castle
-    - king : King
-    + App()
-    + createKingdom(factory : KingdomFactory)
-    + getArmy() : Army
-    ~ getArmy(factory : KingdomFactory) : Army
-    + getCastle() : Castle
-    ~ getCastle(factory : KingdomFactory) : Castle
-    + getKing() : King
-    ~ getKing(factory : KingdomFactory) : King
-    + main(args : String[]) {static}
-    - setArmy(army : Army)
-    - setCastle(castle : Castle)
-    - setKing(king : King)
-  }
-  interface Army {
-    + getDescription() : String {abstract}
-  }
-  interface Castle {
-    + getDescription() : String {abstract}
-  }
-  class ElfArmy {
-    ~ DESCRIPTION : String {static}
-    + ElfArmy()
-    + getDescription() : String
-  }
-  class ElfCastle {
-    ~ DESCRIPTION : String {static}
-    + ElfCastle()
-    + getDescription() : String
-  }
-  class ElfKing {
-    ~ DESCRIPTION : String {static}
-    + ElfKing()
-    + getDescription() : String
-  }
-  class ElfKingdomFactory {
-    + ElfKingdomFactory()
-    + createArmy() : Army
-    + createCastle() : Castle
-    + createKing() : King
-  }
-  interface King {
-    + getDescription() : String {abstract}
-  }
-  interface KingdomFactory {
-    + createArmy() : Army {abstract}
-    + createCastle() : Castle {abstract}
-    + createKing() : King {abstract}
-  }
-  class OrcArmy {
-    ~ DESCRIPTION : String {static}
-    + OrcArmy()
-    + getDescription() : String
-  }
-  class OrcCastle {
-    ~ DESCRIPTION : String {static}
-    + OrcCastle()
-    + getDescription() : String
-  }
-  class OrcKing {
-    ~ DESCRIPTION : String {static}
-    + OrcKing()
-    + getDescription() : String
-  }
-  class OrcKingdomFactory {
-    + OrcKingdomFactory()
-    + createArmy() : Army
-    + createCastle() : Castle
-    + createKing() : King
-  }
-}
-App -->  "-castle" Castle
-App -->  "-king" King
-App -->  "-army" Army
-ElfArmy ..|> Army 
-ElfCastle ..|> Castle 
-ElfKing ..|> King 
-ElfKingdomFactory ..|> KingdomFactory 
-OrcArmy ..|> Army 
-OrcCastle ..|> Castle 
-OrcKing ..|> King 
-OrcKingdomFactory ..|> KingdomFactory 
-@enduml

adapter/README.md

@@ -19,10 +19,85 @@ Convert the interface of a class into another interface the clients
 expect. Adapter lets classes work together that couldn't otherwise because of
 incompatible interfaces.
 
-![alt text](./etc/adapter.png "Adapter")
+## Explanation
 
-## General usage of Adapter Pattern: 
+Real world example
-+ Wrappers used to adopt 3rd parties libraries and frameworks - most of the applications using third party libraries use adapters as a middle layer between the application and the 3rd party library to decouple the application from the library. If another library has to be used only an adapter for the new library is required without having to change the application code.
+
+> Consider that you have some pictures in your memory card and you need to transfer them to your computer. In order to transfer them you need some kind of adapter that is compatible with your computer ports so that you can attach memory card to your computer. In this case card reader is an adapter.
+> Another example would be the famous power adapter; a three legged plug can't be connected to a two pronged outlet, it needs to use a power adapter that makes it compatible with the two pronged outlet.
+> Yet another example would be a translator translating words spoken by one person to another
+
+In plain words
+
+> Adapter pattern lets you wrap an otherwise incompatible object in an adapter to make it compatible with another class.
+
+Wikipedia says
+
+> In software engineering, the adapter pattern is a software design pattern that allows the interface of an existing class to be used as another interface. It is often used to make existing classes work with others without modifying their source code.
+
+**Programmatic Example**
+
+Consider a captain that can only use rowing boats and cannot sail at all.
+
+First we have interfaces `RowingBoat` and `FishingBoat`
+
+```
+public interface RowingBoat {
+  void row();
+}
+
+public class FishingBoat {
+  private static final Logger LOGGER = LoggerFactory.getLogger(FishingBoat.class);
+  public void sail() {
+    LOGGER.info("The fishing boat is sailing");
+  }
+}
+```
+
+And captain expects an implementation of `RowingBoat` interface to be able to move
+
+```
+public class Captain implements RowingBoat {
+
+  private RowingBoat rowingBoat;
+
+  public Captain(RowingBoat rowingBoat) {
+    this.rowingBoat = rowingBoat;
+  }
+
+  @Override
+  public void row() {
+    rowingBoat.row();
+  }
+}
+```
+
+Now let's say the pirates are coming and our captain needs to escape but there is only fishing boat available. We need to create an adapter that allows the captain to operate the fishing boat with his rowing boat skills.
+
+```
+public class FishingBoatAdapter implements RowingBoat {
+
+  private static final Logger LOGGER = LoggerFactory.getLogger(FishingBoatAdapter.class);
+
+  private FishingBoat boat;
+
+  public FishingBoatAdapter() {
+    boat = new FishingBoat();
+  }
+
+  @Override
+  public void row() {
+    boat.sail();
+  }
+}
+```
+
+And now the `Captain` can use the `FishingBoat` to escape the pirates.
+
+```
+Captain captain = new Captain(new FishingBoatAdapter());
+captain.row();
+```
 
 ## Applicability
 Use the Adapter pattern when
@@ -30,6 +105,7 @@ Use the Adapter pattern when
 * you want to use an existing class, and its interface does not match the one you need
 * you want to create a reusable class that cooperates with unrelated or unforeseen classes, that is, classes that don't necessarily have compatible interfaces
 * you need to use several existing subclasses, but it's impractical to adapt their interface by subclassing every one. An object adapter can adapt the interface of its parent class.
+* most of the applications using third party libraries use adapters as a middle layer between the application and the 3rd party library to decouple the application from the library. If another library has to be used only an adapter for the new library is required without having to change the application code.
 
 ## Consequences:
 Class and object adapters have different trade-offs. A class adapter

adapter/etc/adapter.ucls

@@ -1,70 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<class-diagram version="1.1.9" icons="true" always-add-relationships="false" generalizations="true" realizations="true" 
-  associations="true" dependencies="false" nesting-relationships="true" router="FAN">  
-  <class id="1" language="java" name="com.iluwatar.adapter.FishingBoat" project="adapter" 
-    file="/adapter/src/main/java/com/iluwatar/adapter/FishingBoat.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="-1" width="-1" x="656" y="355"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </class>  
-  <class id="2" language="java" name="com.iluwatar.adapter.Captain" project="adapter" 
-    file="/adapter/src/main/java/com/iluwatar/adapter/Captain.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="-1" width="-1" x="228" y="185"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </class>  
-  <class id="3" language="java" name="com.iluwatar.adapter.BattleFishingBoat" project="adapter" 
-    file="/adapter/src/main/java/com/iluwatar/adapter/BattleFishingBoat.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="-1" width="-1" x="463" y="357"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </class>  
-  <interface id="4" language="java" name="com.iluwatar.adapter.BattleShip" project="adapter" 
-    file="/adapter/src/main/java/com/iluwatar/adapter/BattleShip.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="-1" width="-1" x="466" y="170"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </interface>  
-  <realization id="5">    
-    <end type="SOURCE" refId="2"/>    
-    <end type="TARGET" refId="4"/>  
-  </realization>  
-  <association id="6">    
-    <end type="SOURCE" refId="3" navigable="false">      
-      <attribute id="7" name="boat"/>      
-      <multiplicity id="8" minimum="0" maximum="1"/>    
-    </end>    
-    <end type="TARGET" refId="1" navigable="true"/>    
-    <display labels="true" multiplicity="true"/>  
-  </association>  
-  <realization id="9">    
-    <end type="SOURCE" refId="3"/>    
-    <end type="TARGET" refId="4"/>  
-  </realization>  
-  <association id="10">    
-    <end type="SOURCE" refId="2" navigable="false">      
-      <attribute id="11" name="battleship"/>      
-      <multiplicity id="12" minimum="0" maximum="1"/>    
-    </end>    
-    <end type="TARGET" refId="4" navigable="true"/>    
-    <display labels="true" multiplicity="true"/>  
-  </association>  
-  <classifier-display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-    sort-features="false" accessors="true" visibility="true">    
-    <attributes public="true" package="true" protected="true" private="true" static="true"/>    
-    <operations public="true" package="true" protected="true" private="true" static="true"/>  
-  </classifier-display>  
-  <association-display labels="true" multiplicity="true"/>
-</class-diagram>

adapter/etc/adapter.urm.puml

@@ -1,37 +0,0 @@
-@startuml
-package com.iluwatar.adapter {
-  class App {
-    + App()
-    + main(args : String[]) {static}
-  }
-  class BattleFishingBoat {
-    - LOGGER : Logger {static}
-    - boat : FishingBoat
-    + BattleFishingBoat()
-    + fire()
-    + move()
-  }
-  interface BattleShip {
-    + fire() {abstract}
-    + move() {abstract}
-  }
-  class Captain {
-    - battleship : BattleShip
-    + Captain()
-    + Captain(battleship : BattleShip)
-    + fire()
-    + move()
-    + setBattleship(battleship : BattleShip)
-  }
-  class FishingBoat {
-    - LOGGER : Logger {static}
-    + FishingBoat()
-    + fish()
-    + sail()
-  }
-}
-BattleFishingBoat -->  "-boat" FishingBoat
-Captain -->  "-battleship" BattleShip
-BattleFishingBoat ..|> BattleShip 
-Captain ..|> BattleShip 
-@enduml

adapter/src/main/java/com/iluwatar/adapter/App.java

@@ -34,14 +34,14 @@ package com.iluwatar.adapter;
  * object. This example uses the object adapter approach.
  *
  * <p>
- * The Adapter ({@link BattleFishingBoat}) converts the interface of the adaptee class (
+ * The Adapter ({@link FishingBoatAdapter}) converts the interface of the adaptee class (
- * {@link FishingBoat}) into a suitable one expected by the client ( {@link BattleShip} ).
+ * {@link FishingBoat}) into a suitable one expected by the client ( {@link RowingBoat} ).
  *
  * <p>
  * The story of this implementation is this. <br>
- * Pirates are coming! we need a {@link BattleShip} to fight! We have a {@link FishingBoat} and our
+ * Pirates are coming! we need a {@link RowingBoat} to flee! We have a {@link FishingBoat} and our
  * captain. We have no time to make up a new ship! we need to reuse this {@link FishingBoat}. The
- * captain needs a battleship which can fire and move. The spec is in {@link BattleShip}. We will
+ * captain needs a rowing boat which he can operate. The spec is in {@link RowingBoat}. We will
  * use the Adapter pattern to reuse {@link FishingBoat}.
  *
  */
@@ -53,8 +53,8 @@ public class App {
    * @param args command line args
    */
   public static void main(String[] args) {
-    Captain captain = new Captain(new BattleFishingBoat());
+    // The captain can only operate rowing boats but with adapter he is able to use fishing boats as well
-    captain.move();
+    Captain captain = new Captain(new FishingBoatAdapter());
-    captain.fire();
+    captain.row();
   }
 }

adapter/src/main/java/com/iluwatar/adapter/BattleFishingBoat.java

@@ -1,56 +0,0 @@
-/**
- * The MIT License
- * Copyright (c) 2014-2016 Ilkka Seppälä
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- * THE SOFTWARE.
- */
-package com.iluwatar.adapter;
-
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
-/**
- *
- * Adapter class. Adapts the interface of the device ({@link FishingBoat}) into {@link BattleShip}
- * interface expected by the client ({@link Captain}). <br>
- * In this case we added a new function fire to suit the interface. We are reusing the
- * {@link FishingBoat} without changing itself. The Adapter class can just map the functions of the
- * Adaptee or add, delete features of the Adaptee.
- *
- */
-public class BattleFishingBoat implements BattleShip {
-
-  private static final Logger LOGGER = LoggerFactory.getLogger(BattleFishingBoat.class);
-
-  private FishingBoat boat;
-
-  public BattleFishingBoat() {
-    boat = new FishingBoat();
-  }
-
-  @Override
-  public void fire() {
-    LOGGER.info("fire!");
-  }
-
-  @Override
-  public void move() {
-    boat.sail();
-  }
-}

adapter/src/main/java/com/iluwatar/adapter/Captain.java

@@ -23,33 +23,26 @@
 package com.iluwatar.adapter;
 
 /**
- * The Captain uses {@link BattleShip} to fight. <br>
+ * The Captain uses {@link RowingBoat} to sail. <br>
  * This is the client in the pattern.
  */
-public class Captain implements BattleShip {
+public class Captain implements RowingBoat {
 
-  private BattleShip battleship;
+  private RowingBoat rowingBoat;
 
-  public Captain() {
+  public Captain() {}
 
+  public Captain(RowingBoat rowingBoat) {
+    this.rowingBoat = rowingBoat;
   }
 
-  public Captain(BattleShip battleship) {
+  public void setRowingBoat(RowingBoat rowingBoat) {
-    this.battleship = battleship;
+    this.rowingBoat = rowingBoat;
-  }
-
-  public void setBattleship(BattleShip battleship) {
-    this.battleship = battleship;
   }
 
   @Override
-  public void fire() {
+  public void row() {
-    battleship.fire();
+    rowingBoat.row();
-  }
-
-  @Override
-  public void move() {
-    battleship.move();
   }
 
 }

adapter/src/main/java/com/iluwatar/adapter/FishingBoat.java

@@ -27,7 +27,8 @@ import org.slf4j.LoggerFactory;
 
 /**
  *
- * Device class (adaptee in the pattern). We want to reuse this class
+ * Device class (adaptee in the pattern). We want to reuse this class.
+ * Fishing boat moves by sailing.
  *
  */
 public class FishingBoat {
@@ -35,11 +36,7 @@ public class FishingBoat {
   private static final Logger LOGGER = LoggerFactory.getLogger(FishingBoat.class);
 
   public void sail() {
-    LOGGER.info("The Boat is moving to that place");
+    LOGGER.info("The fishing boat is sailing");
-  }
-
-  public void fish() {
-    LOGGER.info("fishing ...");
   }
 
 }

adapter/src/main/java/com/iluwatar/adapter/FishingBoatAdapter.java

@@ -20,28 +20,24 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
-package com.iluwatar.bridge;
+package com.iluwatar.adapter;
 
 /**
  *
- * MagicWeapon
+ * Adapter class. Adapts the interface of the device ({@link FishingBoat}) into {@link RowingBoat}
+ * interface expected by the client ({@link Captain}).
  *
  */
-public abstract class MagicWeapon {
+public class FishingBoatAdapter implements RowingBoat {
 
-  protected MagicWeaponImpl imp;
+  private FishingBoat boat;
 
-  public MagicWeapon(MagicWeaponImpl imp) {
+  public FishingBoatAdapter() {
-    this.imp = imp;
+    boat = new FishingBoat();
   }
 
-  public abstract void wield();
+  @Override
-
+  public void row() {
-  public abstract void swing();
+    boat.sail();
-
-  public abstract void unwield();
-
-  public MagicWeaponImpl getImp() {
-    return imp;
   }
 }

adapter/src/main/java/com/iluwatar/adapter/RowingBoat.java

@@ -24,13 +24,11 @@ package com.iluwatar.adapter;
 
 /**
  * The interface expected by the client.<br>
- * A Battleship can fire and move.
+ * A rowing boat is rowed to move.
  *
  */
-public interface BattleShip {
+public interface RowingBoat {
 
-  void fire();
+  void row();
-
-  void move();
 
 }

adapter/src/test/java/com/iluwatar/adapter/AdapterPatternTest.java

@@ -39,9 +39,9 @@ public class AdapterPatternTest {
 
   private Map<String, Object> beans;
 
-  private static final String BATTLESHIP_BEAN = "engineer";
+  private static final String FISHING_BEAN = "fisher";
 
-  private static final String CAPTAIN_BEAN = "captain";
+  private static final String ROWING_BEAN = "captain";
 
   /**
    * This method runs before the test execution and sets the bean objects in the beans Map.
@@ -50,34 +50,29 @@ public class AdapterPatternTest {
   public void setup() {
     beans = new HashMap<>();
 
-    BattleFishingBoat battleFishingBoat = spy(new BattleFishingBoat());
+    FishingBoatAdapter fishingBoatAdapter = spy(new FishingBoatAdapter());
-    beans.put(BATTLESHIP_BEAN, battleFishingBoat);
+    beans.put(FISHING_BEAN, fishingBoatAdapter);
 
     Captain captain = new Captain();
-    captain.setBattleship((BattleFishingBoat) beans.get(BATTLESHIP_BEAN));
+    captain.setRowingBoat((FishingBoatAdapter) beans.get(FISHING_BEAN));
-    beans.put(CAPTAIN_BEAN, captain);
+    beans.put(ROWING_BEAN, captain);
   }
 
   /**
-   * This test asserts that when we use the move() method on a captain bean(client), it is
+   * This test asserts that when we use the row() method on a captain bean(client), it is
-   * internally calling move method on the battleship object. The Adapter ({@link BattleFishingBoat}
+   * internally calling sail method on the fishing boat object. The Adapter ({@link FishingBoatAdapter}
    * ) converts the interface of the target class ( {@link FishingBoat}) into a suitable one
    * expected by the client ({@link Captain} ).
    */
   @Test
   public void testAdapter() {
-    BattleShip captain = (BattleShip) beans.get(CAPTAIN_BEAN);
+    RowingBoat captain = (RowingBoat) beans.get(ROWING_BEAN);
 
     // when captain moves
-    captain.move();
+    captain.row();
 
     // the captain internally calls the battleship object to move
-    BattleShip battleship = (BattleShip) beans.get(BATTLESHIP_BEAN);
+    RowingBoat adapter = (RowingBoat) beans.get(FISHING_BEAN);
-    verify(battleship).move();
+    verify(adapter).row();
-
-    // same with above with firing
-    captain.fire();
-    verify(battleship).fire();
-
   }
 }

async-method-invocation/src/main/java/com/iluwatar/async/method/invocation/ThreadAsyncExecutor.java

@@ -139,7 +139,7 @@ public class ThreadAsyncExecutor implements AsyncExecutor {
     @Override
     public void await() throws InterruptedException {
       synchronized (lock) {
-        if (!isCompleted()) {
+        while (!isCompleted()) {
           lock.wait();
         }
       }

balking/README.md

@@ -23,5 +23,5 @@ Use the Balking pattern when
 but for an unknown amount of time
 
 ## Related patterns
-* Guarded Suspendion Pattern
+* Guarded Suspension Pattern
 * Double Checked Locking Pattern

bridge/README.md

@@ -15,10 +15,170 @@ tags:
 Handle/Body
 
 ## Intent
-Decouple an abstraction from its implementation so that the two can
+Decouple an abstraction from its implementation so that the two can vary independently.
-vary independently.
 
-![alt text](./etc/bridge.png "Bridge")
+## Explanation
+
+Real world example
+
+> Consider you have a weapon with different enchantments and you are supposed to allow mixing different weapons with different enchantments. What would you do? Create multiple copies of each of the weapons for each of the enchantments or would you just create separate enchantment and set it for the weapon as needed? Bridge pattern allows you to do the second.
+
+In Plain Words
+
+> Bridge pattern is about preferring composition over inheritance. Implementation details are pushed from a hierarchy to another object with a separate hierarchy.
+
+Wikipedia says
+
+> The bridge pattern is a design pattern used in software engineering that is meant to "decouple an abstraction from its implementation so that the two can vary independently"
+
+**Programmatic Example**
+
+Translating our weapon example from above. Here we have the `Weapon` hierarchy
+
+```
+public interface Weapon {
+  void wield();
+  void swing();
+  void unwield();
+  Enchantment getEnchantment();
+}
+
+public class Sword implements Weapon {
+
+  private final Enchantment enchantment;
+
+  public Sword(Enchantment enchantment) {
+    this.enchantment = enchantment;
+  }
+
+  @Override
+  public void wield() {
+    LOGGER.info("The sword is wielded.");
+    enchantment.onActivate();
+  }
+
+  @Override
+  public void swing() {
+    LOGGER.info("The sword is swinged.");
+    enchantment.apply();
+  }
+
+  @Override
+  public void unwield() {
+    LOGGER.info("The sword is unwielded.");
+    enchantment.onDeactivate();
+  }
+
+  @Override
+  public Enchantment getEnchantment() {
+    return enchantment;
+  }
+}
+
+public class Hammer implements Weapon {
+
+  private final Enchantment enchantment;
+
+  public Hammer(Enchantment enchantment) {
+    this.enchantment = enchantment;
+  }
+
+  @Override
+  public void wield() {
+    LOGGER.info("The hammer is wielded.");
+    enchantment.onActivate();
+  }
+
+  @Override
+  public void swing() {
+    LOGGER.info("The hammer is swinged.");
+    enchantment.apply();
+  }
+
+  @Override
+  public void unwield() {
+    LOGGER.info("The hammer is unwielded.");
+    enchantment.onDeactivate();
+  }
+
+  @Override
+  public Enchantment getEnchantment() {
+    return enchantment;
+  }
+}
+```
+
+And the separate enchantment hierarchy
+
+```
+public interface Enchantment {
+  void onActivate();
+  void apply();
+  void onDeactivate();
+}
+
+public class FlyingEnchantment implements Enchantment {
+
+  @Override
+  public void onActivate() {
+    LOGGER.info("The item begins to glow faintly.");
+  }
+
+  @Override
+  public void apply() {
+    LOGGER.info("The item flies and strikes the enemies finally returning to owner's hand.");
+  }
+
+  @Override
+  public void onDeactivate() {
+    LOGGER.info("The item's glow fades.");
+  }
+}
+
+public class SoulEatingEnchantment implements Enchantment {
+
+  @Override
+  public void onActivate() {
+    LOGGER.info("The item spreads bloodlust.");
+  }
+
+  @Override
+  public void apply() {
+    LOGGER.info("The item eats the soul of enemies.");
+  }
+
+  @Override
+  public void onDeactivate() {
+    LOGGER.info("Bloodlust slowly disappears.");
+  }
+}
+```
+
+And both the hierarchies in action
+
+```
+Sword enchantedSword = new Sword(new SoulEatingEnchantment());
+enchantedSword.wield();
+enchantedSword.swing();
+enchantedSword.unwield();
+// The sword is wielded.
+// The item spreads bloodlust.
+// The sword is swinged.
+// The item eats the soul of enemies.
+// The sword is unwielded.
+// Bloodlust slowly disappears.
+
+Hammer hammer = new Hammer(new FlyingEnchantment());
+hammer.wield();
+hammer.swing();
+hammer.unwield();
+// The hammer is wielded.
+// The item begins to glow faintly.
+// The hammer is swinged.
+// The item flies and strikes the enemies finally returning to owner's hand.
+// The hammer is unwielded.
+// The item's glow fades.
+```
 
 ## Applicability
 Use the Bridge pattern when

bridge/etc/bridge.ucls

@@ -1,157 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<class-diagram version="1.1.8" icons="true" automaticImage="PNG" always-add-relationships="false" generalizations="true" 
-  realizations="true" associations="true" dependencies="false" nesting-relationships="true">  
-  <class id="1" language="java" name="com.iluwatar.bridge.FlyingMagicWeaponImpl" project="bridge" 
-    file="/bridge/src/main/java/com/iluwatar/bridge/FlyingMagicWeaponImpl.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="-1" width="-1" x="515" y="591"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </class>  
-  <class id="2" language="java" name="com.iluwatar.bridge.SoulEatingMagicWeaponImpl" project="bridge" 
-    file="/bridge/src/main/java/com/iluwatar/bridge/SoulEatingMagicWeaponImpl.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="-1" width="-1" x="791" y="605"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </class>  
-  <class id="3" language="java" name="com.iluwatar.bridge.Stormbringer" project="bridge" 
-    file="/bridge/src/main/java/com/iluwatar/bridge/Stormbringer.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="-1" width="-1" x="791" y="788"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </class>  
-  <class id="4" language="java" name="com.iluwatar.bridge.MagicWeaponImpl" project="bridge" 
-    file="/bridge/src/main/java/com/iluwatar/bridge/MagicWeaponImpl.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="-1" width="-1" x="791" y="433"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </class>  
-  <class id="5" language="java" name="com.iluwatar.bridge.BlindingMagicWeaponImpl" project="bridge" 
-    file="/bridge/src/main/java/com/iluwatar/bridge/BlindingMagicWeaponImpl.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="-1" width="-1" x="1105" y="593"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </class>  
-  <class id="6" language="java" name="com.iluwatar.bridge.SoulEatingMagicWeapon" project="bridge" 
-    file="/bridge/src/main/java/com/iluwatar/bridge/SoulEatingMagicWeapon.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="-1" width="-1" x="380" y="21"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </class>  
-  <class id="7" language="java" name="com.iluwatar.bridge.Excalibur" project="bridge" 
-    file="/bridge/src/main/java/com/iluwatar/bridge/Excalibur.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="-1" width="-1" x="1105" y="782"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </class>  
-  <class id="8" language="java" name="com.iluwatar.bridge.Mjollnir" project="bridge" 
-    file="/bridge/src/main/java/com/iluwatar/bridge/Mjollnir.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="-1" width="-1" x="515" y="788"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </class>  
-  <class id="9" language="java" name="com.iluwatar.bridge.BlindingMagicWeapon" project="bridge" 
-    file="/bridge/src/main/java/com/iluwatar/bridge/BlindingMagicWeapon.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="-1" width="-1" x="791" y="14"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </class>  
-  <class id="10" language="java" name="com.iluwatar.bridge.MagicWeapon" project="bridge" 
-    file="/bridge/src/main/java/com/iluwatar/bridge/MagicWeapon.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="-1" width="-1" x="791" y="237"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </class>  
-  <class id="11" language="java" name="com.iluwatar.bridge.FlyingMagicWeapon" project="bridge" 
-    file="/bridge/src/main/java/com/iluwatar/bridge/FlyingMagicWeapon.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="-1" width="-1" x="1144" y="12"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </class>  
-  <generalization id="12">    
-    <end type="SOURCE" refId="8"/>    
-    <end type="TARGET" refId="1"/>  
-  </generalization>  
-  <generalization id="13">    
-    <end type="SOURCE" refId="1"/>    
-    <end type="TARGET" refId="4"/>  
-  </generalization>  
-  <generalization id="14">    
-    <end type="SOURCE" refId="9"/>    
-    <end type="TARGET" refId="10"/>  
-  </generalization>  
-  <generalization id="15">    
-    <end type="SOURCE" refId="2"/>    
-    <end type="TARGET" refId="4"/>  
-  </generalization>  
-  <association id="16">    
-    <end type="SOURCE" refId="10" navigable="false">      
-      <attribute id="17" name="imp">        
-        <position height="0" width="0" x="478" y="284"/>      
-      </attribute>      
-      <multiplicity id="18" minimum="0" maximum="1">        
-        <position height="0" width="0" x="478" y="284"/>      
-      </multiplicity>    
-    </end>    
-    <end type="TARGET" refId="4" navigable="true"/>    
-    <display labels="true" multiplicity="true"/>  
-  </association>  
-  <generalization id="19">    
-    <end type="SOURCE" refId="5"/>    
-    <end type="TARGET" refId="4"/>  
-  </generalization>  
-  <generalization id="20">    
-    <end type="SOURCE" refId="6"/>    
-    <end type="TARGET" refId="10"/>  
-  </generalization>  
-  <generalization id="21">    
-    <end type="SOURCE" refId="7"/>    
-    <end type="TARGET" refId="5"/>  
-  </generalization>  
-  <generalization id="22">    
-    <end type="SOURCE" refId="3"/>    
-    <end type="TARGET" refId="2"/>  
-  </generalization>  
-  <generalization id="23">    
-    <end type="SOURCE" refId="11"/>    
-    <end type="TARGET" refId="10"/>  
-  </generalization>  
-  <classifier-display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-    sort-features="false" accessors="true" visibility="true">    
-    <attributes public="true" package="true" protected="true" private="true" static="true"/>    
-    <operations public="true" package="true" protected="true" private="true" static="true"/>  
-  </classifier-display>  
-  <association-display labels="true" multiplicity="true"/>
-</class-diagram>

bridge/etc/bridge.urm.puml

@@ -1,92 +0,0 @@
-@startuml
-package com.iluwatar.bridge {
-  class App {
-    + App()
-    + main(args : String[]) {static}
-  }
-  class BlindingMagicWeapon {
-    + BlindingMagicWeapon(imp : BlindingMagicWeaponImpl)
-    + blind()
-    + getImp() : BlindingMagicWeaponImpl
-    + swing()
-    + unwield()
-    + wield()
-  }
-  abstract class BlindingMagicWeaponImpl {
-    + BlindingMagicWeaponImpl()
-    + blindImp() {abstract}
-  }
-  class Excalibur {
-    - LOGGER : Logger {static}
-    + Excalibur()
-    + blindImp()
-    + swingImp()
-    + unwieldImp()
-    + wieldImp()
-  }
-  class FlyingMagicWeapon {
-    + FlyingMagicWeapon(imp : FlyingMagicWeaponImpl)
-    + fly()
-    + getImp() : FlyingMagicWeaponImpl
-    + swing()
-    + unwield()
-    + wield()
-  }
-  abstract class FlyingMagicWeaponImpl {
-    + FlyingMagicWeaponImpl()
-    + flyImp() {abstract}
-  }
-  abstract class MagicWeapon {
-    # imp : MagicWeaponImpl
-    + MagicWeapon(imp : MagicWeaponImpl)
-    + getImp() : MagicWeaponImpl
-    + swing() {abstract}
-    + unwield() {abstract}
-    + wield() {abstract}
-  }
-  abstract class MagicWeaponImpl {
-    + MagicWeaponImpl()
-    + swingImp() {abstract}
-    + unwieldImp() {abstract}
-    + wieldImp() {abstract}
-  }
-  class Mjollnir {
-    - LOGGER : Logger {static}
-    + Mjollnir()
-    + flyImp()
-    + swingImp()
-    + unwieldImp()
-    + wieldImp()
-  }
-  class SoulEatingMagicWeapon {
-    + SoulEatingMagicWeapon(imp : SoulEatingMagicWeaponImpl)
-    + eatSoul()
-    + getImp() : SoulEatingMagicWeaponImpl
-    + swing()
-    + unwield()
-    + wield()
-  }
-  abstract class SoulEatingMagicWeaponImpl {
-    + SoulEatingMagicWeaponImpl()
-    + eatSoulImp() {abstract}
-  }
-  class Stormbringer {
-    - LOGGER : Logger {static}
-    + Stormbringer()
-    + eatSoulImp()
-    + swingImp()
-    + unwieldImp()
-    + wieldImp()
-  }
-}
-MagicWeapon -->  "-imp" MagicWeaponImpl
-BlindingMagicWeapon --|> MagicWeapon 
-BlindingMagicWeaponImpl --|> MagicWeaponImpl 
-Excalibur --|> BlindingMagicWeaponImpl 
-FlyingMagicWeapon --|> MagicWeapon 
-FlyingMagicWeaponImpl --|> MagicWeaponImpl 
-Mjollnir --|> FlyingMagicWeaponImpl 
-SoulEatingMagicWeapon --|> MagicWeapon 
-SoulEatingMagicWeaponImpl --|> MagicWeaponImpl 
-Stormbringer --|> SoulEatingMagicWeaponImpl 
-@enduml

bridge/src/main/java/com/iluwatar/bridge/App.java

@@ -22,40 +22,42 @@
  */
 package com.iluwatar.bridge;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 /**
  * 
- * The Bridge pattern can also be thought of as two layers of abstraction. With Bridge, you can
+ * Composition over inheritance. The Bridge pattern can also be thought of as two layers of abstraction.
- * decouple an abstraction from its implementation so that the two can vary independently.
+ * With Bridge, you can decouple an abstraction from its implementation so that the two can vary independently.
  * <p>
- * In Bridge pattern both abstraction ({@link MagicWeapon}) and implementation (
+ * In Bridge pattern both abstraction ({@link Weapon}) and implementation (
- * {@link MagicWeaponImpl}) have their own class hierarchies. The interface of the implementations
+ * {@link Enchantment}) have their own class hierarchies. The interface of the implementations
  * can be changed without affecting the clients.
+ * <p>
+ * In this example we have two class hierarchies. One of weapons and another one of enchantments. We can easily
+ * combine any weapon with any enchantment using composition instead of creating deep class hierarchy.
  * 
  */
 public class App {
 
+  private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
+
   /**
    * Program entry point
    * 
    * @param args command line args
    */
   public static void main(String[] args) {
-    BlindingMagicWeapon blindingMagicWeapon = new BlindingMagicWeapon(new Excalibur());
+    LOGGER.info("The knight receives an enchanted sword.");
-    blindingMagicWeapon.wield();
+    Sword enchantedSword = new Sword(new SoulEatingEnchantment());
-    blindingMagicWeapon.blind();
+    enchantedSword.wield();
-    blindingMagicWeapon.swing();
+    enchantedSword.swing();
-    blindingMagicWeapon.unwield();
+    enchantedSword.unwield();
 
-    FlyingMagicWeapon flyingMagicWeapon = new FlyingMagicWeapon(new Mjollnir());
+    LOGGER.info("The valkyrie receives an enchanted hammer.");
-    flyingMagicWeapon.wield();
+    Hammer hammer = new Hammer(new FlyingEnchantment());
-    flyingMagicWeapon.fly();
+    hammer.wield();
-    flyingMagicWeapon.swing();
+    hammer.swing();
-    flyingMagicWeapon.unwield();
+    hammer.unwield();
-
-    SoulEatingMagicWeapon soulEatingMagicWeapon = new SoulEatingMagicWeapon(new Stormbringer());
-    soulEatingMagicWeapon.wield();
-    soulEatingMagicWeapon.swing();
-    soulEatingMagicWeapon.eatSoul();
-    soulEatingMagicWeapon.unwield();
   }
 }

bridge/src/main/java/com/iluwatar/bridge/Enchantment.java

@@ -24,11 +24,14 @@ package com.iluwatar.bridge;
 
 /**
  * 
- * FlyingMagicWeaponImpl
+ * Enchantment
  * 
  */
-public abstract class FlyingMagicWeaponImpl extends MagicWeaponImpl {
+public interface Enchantment {
 
-  public abstract void flyImp();
+  void onActivate();
 
+  void apply();
+
+  void onDeactivate();
 }

bridge/src/main/java/com/iluwatar/bridge/FlyingEnchantment.java

@@ -27,30 +27,25 @@ import org.slf4j.LoggerFactory;
 
 /**
  * 
- * Excalibur
+ * FlyingEnchantment
  *
  */
-public class Excalibur extends BlindingMagicWeaponImpl {
+public class FlyingEnchantment implements Enchantment {
 
-  private static final Logger LOGGER = LoggerFactory.getLogger(Excalibur.class);
+  private static final Logger LOGGER = LoggerFactory.getLogger(FlyingEnchantment.class);
 
   @Override
-  public void wieldImp() {
+  public void onActivate() {
-    LOGGER.info("wielding Excalibur");
+    LOGGER.info("The item begins to glow faintly.");
   }
 
   @Override
-  public void swingImp() {
+  public void apply() {
-    LOGGER.info("swinging Excalibur");
+    LOGGER.info("The item flies and strikes the enemies finally returning to owner's hand.");
   }
 
   @Override
-  public void unwieldImp() {
+  public void onDeactivate() {
-    LOGGER.info("unwielding Excalibur");
+    LOGGER.info("The item's glow fades.");
-  }
-
-  @Override
-  public void blindImp() {
-    LOGGER.info("bright light streams from Excalibur blinding the enemy");
   }
 }

bridge/src/main/java/com/iluwatar/bridge/Hammer.java

@@ -22,38 +22,44 @@
  */
 package com.iluwatar.bridge;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 /**
  * 
- * BlindingMagicWeapon
+ * Hammer
  *
  */
-public class BlindingMagicWeapon extends MagicWeapon {
+public class Hammer implements Weapon {
 
-  public BlindingMagicWeapon(BlindingMagicWeaponImpl imp) {
+  private static final Logger LOGGER = LoggerFactory.getLogger(Hammer.class);
-    super(imp);
-  }
 
-  @Override
+  private final Enchantment enchantment;
-  public BlindingMagicWeaponImpl getImp() {
+
-    return (BlindingMagicWeaponImpl) imp;
+  public Hammer(Enchantment enchantment) {
+    this.enchantment = enchantment;
   }
 
   @Override
   public void wield() {
-    getImp().wieldImp();
+    LOGGER.info("The hammer is wielded.");
+    enchantment.onActivate();
   }
 
   @Override
   public void swing() {
-    getImp().swingImp();
+    LOGGER.info("The hammer is swinged.");
+    enchantment.apply();
   }
 
   @Override
   public void unwield() {
-    getImp().unwieldImp();
+    LOGGER.info("The hammer is unwielded.");
+    enchantment.onDeactivate();
   }
 
-  public void blind() {
+  @Override
-    getImp().blindImp();
+  public Enchantment getEnchantment() {
+    return enchantment;
   }
 }

bridge/src/main/java/com/iluwatar/bridge/MagicWeaponImpl.java

@@ -1,38 +0,0 @@
-/**
- * The MIT License
- * Copyright (c) 2014-2016 Ilkka Seppälä
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- * THE SOFTWARE.
- */
-package com.iluwatar.bridge;
-
-/**
- * 
- * MagicWeaponImpl
- * 
- */
-public abstract class MagicWeaponImpl {
-
-  public abstract void wieldImp();
-
-  public abstract void swingImp();
-
-  public abstract void unwieldImp();
-
-}

bridge/src/main/java/com/iluwatar/bridge/SoulEatingEnchantment.java

@@ -27,30 +27,25 @@ import org.slf4j.LoggerFactory;
 
 /**
  * 
- * Stormbringer
+ * SoulEatingEnchantment
  *
  */
-public class Stormbringer extends SoulEatingMagicWeaponImpl {
+public class SoulEatingEnchantment implements Enchantment {
 
-  private static final Logger LOGGER = LoggerFactory.getLogger(Stormbringer.class);
+  private static final Logger LOGGER = LoggerFactory.getLogger(SoulEatingEnchantment.class);
 
   @Override
-  public void wieldImp() {
+  public void onActivate() {
-    LOGGER.info("wielding Stormbringer");
+    LOGGER.info("The item spreads bloodlust.");
   }
 
   @Override
-  public void swingImp() {
+  public void apply() {
-    LOGGER.info("swinging Stormbringer");
+    LOGGER.info("The item eats the soul of enemies.");
   }
 
   @Override
-  public void unwieldImp() {
+  public void onDeactivate() {
-    LOGGER.info("unwielding Stormbringer");
+    LOGGER.info("Bloodlust slowly disappears.");
-  }
-
-  @Override
-  public void eatSoulImp() {
-    LOGGER.info("Stormbringer devours the enemy's soul");
   }
 }

bridge/src/main/java/com/iluwatar/bridge/SoulEatingMagicWeaponImpl.java

@@ -1,34 +0,0 @@
-/**
- * The MIT License
- * Copyright (c) 2014-2016 Ilkka Seppälä
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- * THE SOFTWARE.
- */
-package com.iluwatar.bridge;
-
-/**
- * 
- * SoulEatingMagicWeaponImpl
- *
- */
-public abstract class SoulEatingMagicWeaponImpl extends MagicWeaponImpl {
-
-  public abstract void eatSoulImp();
-
-}

bridge/src/main/java/com/iluwatar/bridge/Sword.java

@@ -22,39 +22,44 @@
  */
 package com.iluwatar.bridge;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 /**
  * 
- * SoulEatingMagicWeapon
+ * Sword
  *
  */
-public class SoulEatingMagicWeapon extends MagicWeapon {
+public class Sword implements Weapon {
 
-  public SoulEatingMagicWeapon(SoulEatingMagicWeaponImpl imp) {
+  private static final Logger LOGGER = LoggerFactory.getLogger(Sword.class);
-    super(imp);
-  }
 
-  @Override
+  private final Enchantment enchantment;
-  public SoulEatingMagicWeaponImpl getImp() {
+
-    return (SoulEatingMagicWeaponImpl) imp;
+  public Sword(Enchantment enchantment) {
+    this.enchantment = enchantment;
   }
 
   @Override
   public void wield() {
-    getImp().wieldImp();
+    LOGGER.info("The sword is wielded.");
+    enchantment.onActivate();
   }
 
   @Override
   public void swing() {
-    getImp().swingImp();
+    LOGGER.info("The sword is swinged.");
+    enchantment.apply();
   }
 
   @Override
   public void unwield() {
-    getImp().unwieldImp();
+    LOGGER.info("The sword is unwielded.");
+    enchantment.onDeactivate();
   }
 
-  public void eatSoul() {
+  @Override
-    getImp().eatSoulImp();
+  public Enchantment getEnchantment() {
+    return enchantment;
   }
-
 }

bridge/src/main/java/com/iluwatar/bridge/Weapon.java

@@ -24,11 +24,16 @@ package com.iluwatar.bridge;
 
 /**
  * 
- * BlindingMagicWeaponImpl
+ * Weapon
  * 
  */
-public abstract class BlindingMagicWeaponImpl extends MagicWeaponImpl {
+public interface Weapon {
 
-  public abstract void blindImp();
+  void wield();
 
+  void swing();
+
+  void unwield();
+
+  Enchantment getEnchantment();
 }

bridge/src/test/java/com/iluwatar/bridge/HammerTest.java

@@ -24,32 +24,22 @@ package com.iluwatar.bridge;
 
 import org.junit.Test;
 
+import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.spy;
 import static org.mockito.Mockito.verify;
-import static org.mockito.Mockito.verifyNoMoreInteractions;
-import static org.mockito.internal.verification.VerificationModeFactory.times;
 
 /**
- * Date: 12/6/15 - 11:26 PM
+ * Tests for hammer
- *
- * @author Jeroen Meulemeester
  */
-public class FlyingMagicWeaponTest extends MagicWeaponTest {
+public class HammerTest extends WeaponTest {
 
   /**
    * Invoke all possible actions on the weapon and check if the actions are executed on the actual
    * underlying weapon implementation.
    */
   @Test
-  public void testMjollnir() throws Exception {
+  public void testHammer() throws Exception {
-    final Mjollnir mjollnir = spy(new Mjollnir());
+    final Hammer hammer = spy(new Hammer(mock(FlyingEnchantment.class)));
-    final FlyingMagicWeapon flyingMagicWeapon = new FlyingMagicWeapon(mjollnir);
+    testBasicWeaponActions(hammer);
-
-    testBasicWeaponActions(flyingMagicWeapon, mjollnir);
-
-    flyingMagicWeapon.fly();
-    verify(mjollnir, times(1)).flyImp();
-    verifyNoMoreInteractions(mjollnir);
   }
-
 }

bridge/src/test/java/com/iluwatar/bridge/SoulEatingMagicWeaponTest.java

@@ -1,55 +0,0 @@
-/**
- * The MIT License
- * Copyright (c) 2014-2016 Ilkka Seppälä
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- * THE SOFTWARE.
- */
-package com.iluwatar.bridge;
-
-import org.junit.Test;
-
-import static org.mockito.Mockito.spy;
-import static org.mockito.Mockito.verify;
-import static org.mockito.Mockito.verifyNoMoreInteractions;
-import static org.mockito.internal.verification.VerificationModeFactory.times;
-
-/**
- * Date: 12/6/15 - 11:43 PM
- *
- * @author Jeroen Meulemeester
- */
-public class SoulEatingMagicWeaponTest extends MagicWeaponTest {
-
-  /**
-   * Invoke all possible actions on the weapon and check if the actions are executed on the actual
-   * underlying weapon implementation.
-   */
-  @Test
-  public void testStormBringer() throws Exception {
-    final Stormbringer stormbringer = spy(new Stormbringer());
-    final SoulEatingMagicWeapon soulEatingMagicWeapon = new SoulEatingMagicWeapon(stormbringer);
-
-    testBasicWeaponActions(soulEatingMagicWeapon, stormbringer);
-
-    soulEatingMagicWeapon.eatSoul();
-    verify(stormbringer, times(1)).eatSoulImp();
-    verifyNoMoreInteractions(stormbringer);
-  }
-
-}

bridge/src/test/java/com/iluwatar/bridge/SwordTest.java

@@ -22,38 +22,24 @@
  */
 package com.iluwatar.bridge;
 
+import org.junit.Test;
+
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.spy;
+import static org.mockito.Mockito.verify;
+
 /**
- * 
+ * Tests for sword
- * FlyingMagicWeapon
- *
  */
-public class FlyingMagicWeapon extends MagicWeapon {
+public class SwordTest extends WeaponTest {
 
-  public FlyingMagicWeapon(FlyingMagicWeaponImpl imp) {
+  /**
-    super(imp);
+   * Invoke all possible actions on the weapon and check if the actions are executed on the actual
+   * underlying weapon implementation.
+   */
+  @Test
+  public void testSword() throws Exception {
+    final Sword sword = spy(new Sword(mock(FlyingEnchantment.class)));
+    testBasicWeaponActions(sword);
   }
-
-  public FlyingMagicWeaponImpl getImp() {
-    return (FlyingMagicWeaponImpl) imp;
-  }
-
-  @Override
-  public void wield() {
-    getImp().wieldImp();
-  }
-
-  @Override
-  public void swing() {
-    getImp().swingImp();
-  }
-
-  @Override
-  public void unwield() {
-    getImp().unwieldImp();
-  }
-
-  public void fly() {
-    getImp().flyImp();
-  }
-
 }

bridge/src/test/java/com/iluwatar/bridge/WeaponTest.java

@@ -28,37 +28,32 @@ import static org.mockito.Mockito.verifyNoMoreInteractions;
 import static org.mockito.internal.verification.VerificationModeFactory.times;
 
 /**
- * Date: 12/6/15 - 11:28 PM
+ * Base class for weapon tests
- *
- * @author Jeroen Meulemeester
  */
-public abstract class MagicWeaponTest {
+public abstract class WeaponTest {
 
   /**
-   * Invoke the basic actions of the given weapon, and test if the underlying weapon implementation
+   * Invoke the basic actions of the given weapon, and test if the underlying enchantment implementation
    * is invoked
    *
-   * @param weaponImpl The spied weapon implementation where actions are bridged to
-   * @param weapon               The weapon, handled by the app
    */
-  protected final void testBasicWeaponActions(final MagicWeapon weapon,
+  protected final void testBasicWeaponActions(final Weapon weapon) {
-                                              final MagicWeaponImpl weaponImpl) {
     assertNotNull(weapon);
-    assertNotNull(weaponImpl);
+    Enchantment enchantment = weapon.getEnchantment();
-    assertNotNull(weapon.getImp());
+    assertNotNull(enchantment);
+    assertNotNull(weapon.getEnchantment());
 
     weapon.swing();
-    verify(weaponImpl, times(1)).swingImp();
+    verify(enchantment, times(1)).apply();
-    verifyNoMoreInteractions(weaponImpl);
+    verifyNoMoreInteractions(enchantment);
 
     weapon.wield();
-    verify(weaponImpl, times(1)).wieldImp();
+    verify(enchantment, times(1)).onActivate();
-    verifyNoMoreInteractions(weaponImpl);
+    verifyNoMoreInteractions(enchantment);
 
     weapon.unwield();
-    verify(weaponImpl, times(1)).unwieldImp();
+    verify(enchantment, times(1)).onDeactivate();
-    verifyNoMoreInteractions(weaponImpl);
+    verifyNoMoreInteractions(enchantment);
 
   }
-
 }

builder/README.md

@@ -16,7 +16,103 @@ Separate the construction of a complex object from its
 representation so that the same construction process can create different
 representations.
 
-![alt text](./etc/builder_1.png "Builder")
+## Explanation
+
+Real world example
+
+> Imagine a character generator for a role playing game. The easiest option is to let computer create the character for you. But if you want to select the character details like profession, gender, hair color etc. the character generation becomes a step-by-step process that completes when all the selections are ready.
+
+In plain words
+
+> Allows you to create different flavors of an object while avoiding constructor pollution. Useful when there could be several flavors of an object. Or when there are a lot of steps involved in creation of an object.
+
+Wikipedia says
+
+> The builder pattern is an object creation software design pattern with the intentions of finding a solution to the telescoping constructor anti-pattern.
+
+Having said that let me add a bit about what telescoping constructor anti-pattern is. At one point or the other we have all seen a constructor like below:
+
+```
+public Hero(Profession profession, String name, HairType hairType, HairColor hairColor, Armor armor, Weapon weapon) {
+}
+```
+
+As you can see the number of constructor parameters can quickly get out of hand and it might become difficult to understand the arrangement of parameters. Plus this parameter list could keep on growing if you would want to add more options in future. This is called telescoping constructor anti-pattern.
+
+**Programmatic Example**
+
+The sane alternative is to use the Builder pattern. First of all we have our hero that we want to create
+
+```
+public final class Hero {
+  private final Profession profession;
+  private final String name;
+  private final HairType hairType;
+  private final HairColor hairColor;
+  private final Armor armor;
+  private final Weapon weapon;
+
+  private Hero(Builder builder) {
+    this.profession = builder.profession;
+    this.name = builder.name;
+    this.hairColor = builder.hairColor;
+    this.hairType = builder.hairType;
+    this.weapon = builder.weapon;
+    this.armor = builder.armor;
+  }
+}
+```
+
+And then we have the builder
+
+```
+  public static class Builder {
+    private final Profession profession;
+    private final String name;
+    private HairType hairType;
+    private HairColor hairColor;
+    private Armor armor;
+    private Weapon weapon;
+
+    public Builder(Profession profession, String name) {
+      if (profession == null || name == null) {
+        throw new IllegalArgumentException("profession and name can not be null");
+      }
+      this.profession = profession;
+      this.name = name;
+    }
+
+    public Builder withHairType(HairType hairType) {
+      this.hairType = hairType;
+      return this;
+    }
+
+    public Builder withHairColor(HairColor hairColor) {
+      this.hairColor = hairColor;
+      return this;
+    }
+
+    public Builder withArmor(Armor armor) {
+      this.armor = armor;
+      return this;
+    }
+
+    public Builder withWeapon(Weapon weapon) {
+      this.weapon = weapon;
+      return this;
+    }
+
+    public Hero build() {
+      return new Hero(this);
+    }
+  }
+```
+
+And then it can be used as:
+
+```
+Hero mage = new Hero.Builder(Profession.MAGE, "Riobard").withHairColor(HairColor.BLACK).withWeapon(Weapon.DAGGER).build();
+```
 
 ## Applicability
 Use the Builder pattern when

builder/etc/builder.ucls

@@ -1,162 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<class-diagram version="1.1.8" icons="true" automaticImage="PNG" always-add-relationships="false" generalizations="true" 
-  realizations="true" associations="true" dependencies="false" nesting-relationships="true">  
-  <enumeration id="1" language="java" name="com.iluwatar.builder.HairType" project="builder" 
-    file="/builder/src/main/java/com/iluwatar/builder/HairType.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="214" width="189" x="177" y="419"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </enumeration>  
-  <enumeration id="2" language="java" name="com.iluwatar.builder.Weapon" project="builder" 
-    file="/builder/src/main/java/com/iluwatar/builder/Weapon.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="196" width="171" x="406" y="419"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </enumeration>  
-  <enumeration id="3" language="java" name="com.iluwatar.builder.HairColor" project="builder" 
-    file="/builder/src/main/java/com/iluwatar/builder/HairColor.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="196" width="144" x="-204" y="419"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </enumeration>  
-  <class id="4" language="java" name="com.iluwatar.builder.Hero.Builder" project="builder"
-    file="/builder/src/main/java/com/iluwatar/builder/Hero.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="196" width="234" x="20" y="183"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </class>  
-  <enumeration id="5" language="java" name="com.iluwatar.builder.Armor" project="builder" 
-    file="/builder/src/main/java/com/iluwatar/builder/Armor.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="196" width="145" x="617" y="419"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </enumeration>  
-  <enumeration id="6" language="java" name="com.iluwatar.builder.Profession" project="builder" 
-    file="/builder/src/main/java/com/iluwatar/builder/Profession.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="178" width="157" x="-20" y="419"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </enumeration>  
-  <class id="7" language="java" name="com.iluwatar.builder.Hero" project="builder" 
-    file="/builder/src/main/java/com/iluwatar/builder/Hero.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="232" width="178" x="275" y="-89"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </class>  
-  <association id="8">    
-    <bendpoint x="284" y="183"/>    
-    <end type="SOURCE" refId="7" navigable="false">      
-      <attribute id="9" name="hairType"/>      
-      <multiplicity id="10" minimum="0" maximum="1"/>    
-    </end>    
-    <end type="TARGET" refId="1" navigable="true"/>    
-    <display labels="true" multiplicity="true"/>  
-  </association>  
-  <association id="11">    
-    <end type="SOURCE" refId="4" navigable="false">      
-      <attribute id="12" name="weapon"/>      
-      <multiplicity id="13" minimum="0" maximum="1"/>    
-    </end>    
-    <end type="TARGET" refId="2" navigable="true"/>    
-    <display labels="true" multiplicity="true"/>  
-  </association>  
-  <association id="14">    
-    <end type="SOURCE" refId="4" navigable="false">      
-      <attribute id="15" name="profession"/>      
-      <multiplicity id="16" minimum="0" maximum="1"/>    
-    </end>    
-    <end type="TARGET" refId="6" navigable="true"/>    
-    <display labels="true" multiplicity="true"/>  
-  </association>  
-  <association id="17">    
-    <end type="SOURCE" refId="4" navigable="false">      
-      <attribute id="18" name="hairColor"/>      
-      <multiplicity id="19" minimum="0" maximum="1"/>    
-    </end>    
-    <end type="TARGET" refId="3" navigable="true"/>    
-    <display labels="true" multiplicity="true"/>  
-  </association>  
-  <association id="20">    
-    <bendpoint x="350" y="183"/>    
-    <end type="SOURCE" refId="7" navigable="false">      
-      <attribute id="21" name="weapon"/>      
-      <multiplicity id="22" minimum="0" maximum="1"/>    
-    </end>    
-    <end type="TARGET" refId="2" navigable="true"/>    
-    <display labels="true" multiplicity="true"/>  
-  </association>  
-  <association id="23">    
-    <end type="SOURCE" refId="4" navigable="false">      
-      <attribute id="24" name="hairType"/>      
-      <multiplicity id="25" minimum="0" maximum="1"/>    
-    </end>    
-    <end type="TARGET" refId="1" navigable="true"/>    
-    <display labels="true" multiplicity="true"/>  
-  </association>  
-  <nesting id="26">    
-    <end type="SOURCE" refId="7"/>    
-    <end type="TARGET" refId="4"/>  
-  </nesting>  
-  <association id="27">    
-    <end type="SOURCE" refId="4" navigable="false">      
-      <attribute id="28" name="armor"/>      
-      <multiplicity id="29" minimum="0" maximum="1"/>    
-    </end>    
-    <end type="TARGET" refId="5" navigable="true"/>    
-    <display labels="true" multiplicity="true"/>  
-  </association>  
-  <association id="30">    
-    <bendpoint x="-11" y="183"/>    
-    <end type="SOURCE" refId="7" navigable="false">      
-      <attribute id="31" name="profession"/>      
-      <multiplicity id="32" minimum="0" maximum="1"/>    
-    </end>    
-    <end type="TARGET" refId="6" navigable="true"/>    
-    <display labels="true" multiplicity="true"/>  
-  </association>  
-  <association id="33">    
-    <bendpoint x="-32" y="183"/>    
-    <end type="SOURCE" refId="7" navigable="false">      
-      <attribute id="34" name="hairColor"/>      
-      <multiplicity id="35" minimum="0" maximum="1"/>    
-    </end>    
-    <end type="TARGET" refId="3" navigable="true"/>    
-    <display labels="true" multiplicity="true"/>  
-  </association>  
-  <association id="36">    
-    <bendpoint x="455" y="183"/>    
-    <end type="SOURCE" refId="7" navigable="false">      
-      <attribute id="37" name="armor"/>      
-      <multiplicity id="38" minimum="0" maximum="1"/>    
-    </end>    
-    <end type="TARGET" refId="5" navigable="true"/>    
-    <display labels="true" multiplicity="true"/>  
-  </association>  
-  <classifier-display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-    sort-features="false" accessors="true" visibility="true">    
-    <attributes public="true" package="true" protected="true" private="true" static="true"/>    
-    <operations public="true" package="true" protected="true" private="true" static="true"/>  
-  </classifier-display>  
-  <association-display labels="true" multiplicity="true"/>
-</class-diagram>

builder/etc/builder.urm.puml

@@ -1,100 +0,0 @@
-@startuml
-package com.iluwatar.builder {
-  class App {
-    - LOGGER : Logger {static}
-    + App()
-    + main(args : String[]) {static}
-  }
-  enum Armor {
-    + CHAIN_MAIL {static}
-    + CLOTHES {static}
-    + LEATHER {static}
-    + PLATE_MAIL {static}
-    - title : String
-    + toString() : String
-    + valueOf(name : String) : Armor {static}
-    + values() : Armor[] {static}
-  }
-  enum HairColor {
-    + BLACK {static}
-    + BLOND {static}
-    + BROWN {static}
-    + RED {static}
-    + WHITE {static}
-    + toString() : String
-    + valueOf(name : String) : HairColor {static}
-    + values() : HairColor[] {static}
-  }
-  enum HairType {
-    + BALD {static}
-    + CURLY {static}
-    + LONG_CURLY {static}
-    + LONG_STRAIGHT {static}
-    + SHORT {static}
-    - title : String
-    + toString() : String
-    + valueOf(name : String) : HairType {static}
-    + values() : HairType[] {static}
-  }
-  class Hero {
-    - armor : Armor
-    - hairColor : HairColor
-    - hairType : HairType
-    - name : String
-    - profession : Profession
-    - weapon : Weapon
-    - Hero(builder : Builder)
-    + getArmor() : Armor
-    + getHairColor() : HairColor
-    + getHairType() : HairType
-    + getName() : String
-    + getProfession() : Profession
-    + getWeapon() : Weapon
-    + toString() : String
-  }
-  class Builder {
-    - armor : Armor
-    - hairColor : HairColor
-    - hairType : HairType
-    - name : String
-    - profession : Profession
-    - weapon : Weapon
-    + Builder(profession : Profession, name : String)
-    + build() : Hero
-    + withArmor(armor : Armor) : Builder
-    + withHairColor(hairColor : HairColor) : Builder
-    + withHairType(hairType : HairType) : Builder
-    + withWeapon(weapon : Weapon) : Builder
-  }
-  enum Profession {
-    + MAGE {static}
-    + PRIEST {static}
-    + THIEF {static}
-    + WARRIOR {static}
-    + toString() : String
-    + valueOf(name : String) : Profession {static}
-    + values() : Profession[] {static}
-  }
-  enum Weapon {
-    + AXE {static}
-    + BOW {static}
-    + DAGGER {static}
-    + SWORD {static}
-    + WARHAMMER {static}
-    + toString() : String
-    + valueOf(name : String) : Weapon {static}
-    + values() : Weapon[] {static}
-  }
-}
-Builder ..+ Hero
-Hero -->  "-profession" Profession
-Hero -->  "-armor" Armor
-Builder -->  "-hairColor" HairColor
-Builder -->  "-weapon" Weapon
-Builder -->  "-hairType" HairType
-Hero -->  "-hairColor" HairColor
-Builder -->  "-profession" Profession
-Hero -->  "-hairType" HairType
-Hero -->  "-weapon" Weapon
-Builder -->  "-armor" Armor
-@enduml

composite/README.md

@@ -16,7 +16,119 @@ Compose objects into tree structures to represent part-whole
 hierarchies. Composite lets clients treat individual objects and compositions
 of objects uniformly.
 
-![alt text](./etc/composite_1.png "Composite")
+## Explanation
+
+Real world example
+
+> Every sentence is composed of words which are in turn composed of characters. Each of these objects is printable and they can have something printed before or after them like sentence always ends with full stop and word always has space before it
+
+In plain words
+
+> Composite pattern lets clients treat the individual objects in a uniform manner.
+
+Wikipedia says
+
+> In software engineering, the composite pattern is a partitioning design pattern. The composite pattern describes that a group of objects is to be treated in the same way as a single instance of an object. The intent of a composite is to "compose" objects into tree structures to represent part-whole hierarchies. Implementing the composite pattern lets clients treat individual objects and compositions uniformly.
+
+**Programmatic Example**
+
+Taking our sentence example from above. Here we have the base class and different printable types
+
+```
+public abstract class LetterComposite {
+  private List<LetterComposite> children = new ArrayList<>();
+  public void add(LetterComposite letter) {
+    children.add(letter);
+  }
+  public int count() {
+    return children.size();
+  }
+  protected void printThisBefore() {}
+  protected void printThisAfter() {}
+  public void print() {
+    printThisBefore();
+    for (LetterComposite letter : children) {
+      letter.print();
+    }
+    printThisAfter();
+  }
+}
+
+public class Letter extends LetterComposite {
+  private char c;
+  public Letter(char c) {
+    this.c = c;
+  }
+  @Override
+  protected void printThisBefore() {
+    System.out.print(c);
+  }
+}
+
+public class Word extends LetterComposite {
+  public Word(List<Letter> letters) {
+    for (Letter l : letters) {
+      this.add(l);
+    }
+  }
+  @Override
+  protected void printThisBefore() {
+    System.out.print(" ");
+  }
+}
+
+public class Sentence extends LetterComposite {
+  public Sentence(List<Word> words) {
+    for (Word w : words) {
+      this.add(w);
+    }
+  }
+  @Override
+  protected void printThisAfter() {
+    System.out.print(".");
+  }
+}
+```
+
+Then we have a messenger to carry messages
+
+```
+public class Messenger {
+  LetterComposite messageFromOrcs() {
+    List<Word> words = new ArrayList<>();
+    words.add(new Word(Arrays.asList(new Letter('W'), new Letter('h'), new Letter('e'), new Letter('r'), new Letter('e'))));
+    words.add(new Word(Arrays.asList(new Letter('t'), new Letter('h'), new Letter('e'), new Letter('r'), new Letter('e'))));
+    words.add(new Word(Arrays.asList(new Letter('i'), new Letter('s'))));
+    words.add(new Word(Arrays.asList(new Letter('a'))));
+    words.add(new Word(Arrays.asList(new Letter('w'), new Letter('h'), new Letter('i'), new Letter('p'))));
+    words.add(new Word(Arrays.asList(new Letter('t'), new Letter('h'), new Letter('e'), new Letter('r'), new Letter('e'))));
+    words.add(new Word(Arrays.asList(new Letter('i'), new Letter('s'))));
+    words.add(new Word(Arrays.asList(new Letter('a'))));
+    words.add(new Word(Arrays.asList(new Letter('w'), new Letter('a'), new Letter('y'))));
+    return new Sentence(words);
+  }
+
+  LetterComposite messageFromElves() {
+    List<Word> words = new ArrayList<>();
+    words.add(new Word(Arrays.asList(new Letter('M'), new Letter('u'), new Letter('c'), new Letter('h'))));
+    words.add(new Word(Arrays.asList(new Letter('w'), new Letter('i'), new Letter('n'), new Letter('d'))));
+    words.add(new Word(Arrays.asList(new Letter('p'), new Letter('o'), new Letter('u'), new Letter('r'), new Letter('s'))));
+    words.add(new Word(Arrays.asList(new Letter('f'), new Letter('r'), new Letter('o'), new Letter('m'))));
+    words.add(new Word(Arrays.asList(new Letter('y'), new Letter('o'), new Letter('u'), new Letter('r'))));
+    words.add(new Word(Arrays.asList(new Letter('m'), new Letter('o'), new Letter('u'), new Letter('t'), new Letter('h'))));
+    return new Sentence(words);
+  }
+}
+```
+
+And then it can be used as
+
+```
+LetterComposite orcMessage = new Messenger().messageFromOrcs();
+orcMessage.print(); // Where there is a whip there is a way.
+LetterComposite elfMessage = new Messenger().messageFromElves();
+elfMessage.print(); // Much wind pours from your mouth.
+```
 
 ## Applicability
 Use the Composite pattern when

composite/etc/composite.ucls

@@ -1,75 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<class-diagram version="1.1.8" icons="true" automaticImage="PNG" always-add-relationships="false" generalizations="true" 
-  realizations="true" associations="true" dependencies="false" nesting-relationships="true">  
-  <class id="1" language="java" name="com.iluwatar.composite.Messenger" project="composite" 
-    file="/composite/src/main/java/com/iluwatar/composite/Messenger.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="124" width="247" x="118" y="180"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </class>  
-  <class id="2" language="java" name="com.iluwatar.composite.Sentence" project="composite" 
-    file="/composite/src/main/java/com/iluwatar/composite/Sentence.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="124" width="157" x="118" y="407"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </class>  
-  <class id="3" language="java" name="com.iluwatar.composite.LetterComposite" project="composite" 
-    file="/composite/src/main/java/com/iluwatar/composite/LetterComposite.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="177" width="176" x="405" y="180"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </class>  
-  <class id="4" language="java" name="com.iluwatar.composite.Letter" project="composite" 
-    file="/composite/src/main/java/com/iluwatar/composite/Letter.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="142" width="146" x="315" y="407"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </class>  
-  <class id="5" language="java" name="com.iluwatar.composite.Word" project="composite" 
-    file="/composite/src/main/java/com/iluwatar/composite/Word.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="124" width="146" x="501" y="407"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </class>  
-  <generalization id="6">    
-    <end type="SOURCE" refId="2"/>    
-    <end type="TARGET" refId="3"/>  
-  </generalization>  
-  <generalization id="7">    
-    <end type="SOURCE" refId="4"/>    
-    <end type="TARGET" refId="3"/>  
-  </generalization>  
-  <association id="8">    
-    <end type="SOURCE" refId="3" navigable="false">      
-      <attribute id="9" name="children"/>      
-      <multiplicity id="10" minimum="0" maximum="2147483647"/>    
-    </end>    
-    <end type="TARGET" refId="3" navigable="true"/>    
-    <display labels="true" multiplicity="true"/>  
-  </association>  
-  <generalization id="11">    
-    <end type="SOURCE" refId="5"/>    
-    <end type="TARGET" refId="3"/>  
-  </generalization>  
-  <classifier-display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-    sort-features="false" accessors="true" visibility="true">    
-    <attributes public="true" package="true" protected="true" private="true" static="true"/>    
-    <operations public="true" package="true" protected="true" private="true" static="true"/>  
-  </classifier-display>  
-  <association-display labels="true" multiplicity="true"/>
-</class-diagram>

composite/etc/composite.urm.puml

@@ -1,43 +0,0 @@
-@startuml
-package com.iluwatar.composite {
-  class App {
-    - LOGGER : Logger {static}
-    + App()
-    + main(args : String[]) {static}
-  }
-  class Letter {
-    - c : char
-    + Letter(c : char)
-    # printThisAfter()
-    # printThisBefore()
-  }
-  abstract class LetterComposite {
-    - children : List<LetterComposite>
-    + LetterComposite()
-    + add(letter : LetterComposite)
-    + count() : int
-    + print()
-    # printThisAfter() {abstract}
-    # printThisBefore() {abstract}
-  }
-  class Messenger {
-    + Messenger()
-    ~ messageFromElves() : LetterComposite
-    ~ messageFromOrcs() : LetterComposite
-  }
-  class Sentence {
-    + Sentence(words : List<Word>)
-    # printThisAfter()
-    # printThisBefore()
-  }
-  class Word {
-    + Word(letters : List<Letter>)
-    # printThisAfter()
-    # printThisBefore()
-  }
-}
-LetterComposite -->  "-children" LetterComposite
-Letter --|> LetterComposite 
-Sentence --|> LetterComposite 
-Word --|> LetterComposite 
-@enduml

composite/src/main/java/com/iluwatar/composite/App.java

@@ -51,9 +51,7 @@ public class App {
     LetterComposite orcMessage = new Messenger().messageFromOrcs();
     orcMessage.print();
 
-    LOGGER.info("\n");
+    LOGGER.info("\nMessage from the elves: ");
-
-    LOGGER.info("Message from the elves: ");
 
     LetterComposite elfMessage = new Messenger().messageFromElves();
     elfMessage.print();

composite/src/main/java/com/iluwatar/composite/Letter.java

@@ -39,9 +39,4 @@ public class Letter extends LetterComposite {
   protected void printThisBefore() {
     System.out.print(c);
   }
-
-  @Override
-  protected void printThisAfter() {
-    // nop
-  }
 }

composite/src/main/java/com/iluwatar/composite/LetterComposite.java

@@ -42,9 +42,9 @@ public abstract class LetterComposite {
     return children.size();
   }
 
-  protected abstract void printThisBefore();
+  protected void printThisBefore() {}
 
-  protected abstract void printThisAfter();
+  protected void printThisAfter() {}
 
   /**
    * Print

composite/src/main/java/com/iluwatar/composite/Sentence.java

@@ -40,11 +40,6 @@ public class Sentence extends LetterComposite {
     }
   }
 
-  @Override
-  protected void printThisBefore() {
-    // nop
-  }
-
   @Override
   protected void printThisAfter() {
     System.out.print(".");

composite/src/main/java/com/iluwatar/composite/Word.java

@@ -44,9 +44,4 @@ public class Word extends LetterComposite {
   protected void printThisBefore() {
     System.out.print(" ");
   }
-
-  @Override
-  protected void printThisAfter() {
-    // nop
-  }
 }

dao/src/main/java/com/iluwatar/dao/DbCustomerDao.java

@@ -65,8 +65,8 @@ public class DbCustomerDao implements CustomerDao {
     Connection connection;
     try {
       connection = getConnection();
-      PreparedStatement statement = connection.prepareStatement("SELECT * FROM CUSTOMERS");
+      PreparedStatement statement = connection.prepareStatement("SELECT * FROM CUSTOMERS");  //NOSONAR
-      ResultSet resultSet = statement.executeQuery();
+      ResultSet resultSet = statement.executeQuery(); //NOSONAR
       return StreamSupport.stream(new Spliterators.AbstractSpliterator<Customer>(Long.MAX_VALUE, 
           Spliterator.ORDERED) {
 
@@ -82,7 +82,7 @@ public class DbCustomerDao implements CustomerDao {
             throw new RuntimeException(e);
           }
         }
-      }, false).onClose(() -> mutedClose(connection));
+      }, false).onClose(() -> mutedClose(connection, statement, resultSet));
     } catch (SQLException e) {
       throw new Exception(e.getMessage(), e);
     }
@@ -92,8 +92,10 @@ public class DbCustomerDao implements CustomerDao {
     return dataSource.getConnection();
   }
 
-  private void mutedClose(Connection connection) {
+  private void mutedClose(Connection connection, PreparedStatement statement, ResultSet resultSet) {
     try {
+      resultSet.close();
+      statement.close();
       connection.close();
     } catch (SQLException e) {
       e.printStackTrace();

data-transfer-object/README.md

@@ -0,0 +1,31 @@
+---
+layout: pattern
+title: Data Transfer Object
+folder: data-transfer-object
+permalink: /patterns/data-transfer-object/
+pumlid: RSh14SCW30NHLk82GFTq8uDYum71I5zn-t41kUtCswrfwL4bhBzEOFcRoFZEHyCPUxXOcGfHv387jHutWuqk_dAguktGj1WGKwV1_WJLvqWmLl-8fRbVKa22yXTosCWhHly1
+categories: Architectural
+tags:
+ - Java
+ - KISS
+ - YAGNI
+ - Difficulty-Beginner
+---
+
+## Intent
+Pass data with multiple attributes in one shot from client to server,
+to avoid multiple calls to remote server. 
+
+![alt text](./etc/data-transfer-object.urm.png "data-transfer-object")
+
+## Applicability
+Use the Data Transfer Object pattern when
+
+* The client is asking for multiple information. And the information is related.
+* When you want to boost the performance to get resources.
+* You want reduced number of remote calls.
+
+## Credits
+
+* [Design Pattern - Transfer Object Pattern](https://www.tutorialspoint.com/design_pattern/transfer_object_pattern.htm)
+* [Data Transfer Object](https://msdn.microsoft.com/en-us/library/ff649585.aspx)

data-transfer-object/etc/data-transfer-object.ucls

@@ -0,0 +1,48 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<class-diagram version="1.2.0" icons="true" always-add-relationships="false" generalizations="true" realizations="true" 
+  associations="true" dependencies="false" nesting-relationships="true" router="FAN">  
+  <class id="1" language="java" name="com.iluwatar.datatransfer.CustomerClientApp" project="data-transfer-object" 
+    file="/data-transfer-object/src/main/java/com/iluwatar/datatransfer/CustomerClientApp.java" binary="false" 
+    corner="BOTTOM_RIGHT">    
+    <position height="-1" width="-1" x="145" y="93"/>    
+    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
+      sort-features="false" accessors="true" visibility="true">      
+      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
+      <operations public="true" package="true" protected="true" private="true" static="true"/>    
+    </display>  
+  </class>  
+  <class id="2" language="java" name="com.iluwatar.datatransfer.CustomerDto" project="data-transfer-object" 
+    file="/data-transfer-object/src/main/java/com/iluwatar/datatransfer/CustomerDto.java" binary="false" 
+    corner="BOTTOM_RIGHT">    
+    <position height="-1" width="-1" x="386" y="329"/>    
+    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
+      sort-features="false" accessors="true" visibility="true">      
+      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
+      <operations public="true" package="true" protected="true" private="true" static="true"/>    
+    </display>  
+  </class>  
+  <class id="3" language="java" name="com.iluwatar.datatransfer.CustomerResource" project="data-transfer-object" 
+    file="/data-transfer-object/src/main/java/com/iluwatar/datatransfer/CustomerResource.java" binary="false" 
+    corner="BOTTOM_RIGHT">    
+    <position height="-1" width="-1" x="677" y="93"/>    
+    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
+      sort-features="false" accessors="true" visibility="true">      
+      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
+      <operations public="true" package="true" protected="true" private="true" static="true"/>    
+    </display>  
+  </class>  
+  <association id="4">    
+    <end type="SOURCE" refId="3" navigable="false">      
+      <attribute id="5" name="customers"/>      
+      <multiplicity id="6" minimum="0" maximum="2147483647"/>    
+    </end>    
+    <end type="TARGET" refId="2" navigable="true"/>    
+    <display labels="true" multiplicity="true"/>  
+  </association>  
+  <classifier-display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
+    sort-features="false" accessors="true" visibility="true">    
+    <attributes public="true" package="true" protected="true" private="true" static="true"/>    
+    <operations public="true" package="true" protected="true" private="true" static="true"/>  
+  </classifier-display>  
+  <association-display labels="true" multiplicity="true"/>
+</class-diagram>

data-transfer-object/etc/data-transfer-object.urm.puml

@@ -0,0 +1,26 @@
+@startuml
+package com.iluwatar.datatransfer {
+  class CustomerClientApp {
+    + CustomerClientApp()
+    + main(args : String[]) {static}
+    - printCustomerDetails(allCustomers : List<CustomerDto>) {static}
+  }
+  class CustomerDto {
+    - firstName : String
+    - id : String
+    - lastName : String
+    + CustomerDto(id : String, firstName : String, lastName : String)
+    + getFirstName() : String
+    + getId() : String
+    + getLastName() : String
+  }
+  class CustomerResource {
+    - customers : List<CustomerDto>
+    + CustomerResource(customers : List<CustomerDto>)
+    + delete(customerId : String)
+    + getAllCustomers() : List<CustomerDto>
+    + save(customer : CustomerDto)
+  }
+}
+CustomerResource -->  "-customers" CustomerDto
+@enduml

data-transfer-object/pom.xml

@@ -0,0 +1,45 @@
+<?xml version="1.0"?>
+<!--
+
+    The MIT License
+    Copyright (c) 2016 Gopinath Langote
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to deal
+    in the Software without restriction, including without limitation the rights
+    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+    copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in
+    all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+    THE SOFTWARE.
+
+-->
+<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+    <modelVersion>4.0.0</modelVersion>
+    <parent>
+        <groupId>com.iluwatar</groupId>
+        <artifactId>java-design-patterns</artifactId>
+        <version>1.17.0-SNAPSHOT</version>
+    </parent>
+    <artifactId>data-transfer-object</artifactId>
+    <dependencies>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>log4j</groupId>
+            <artifactId>log4j</artifactId>
+        </dependency>
+    </dependencies>
+</project>

data-transfer-object/src/main/java/com/iluwatar/datatransfer/CustomerClientApp.java

@@ -0,0 +1,84 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017 Gopinath Langote
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package com.iluwatar.datatransfer;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * The Data Transfer Object pattern is a design pattern in which an data transfer object is used to serve related
+ * information together to avoid multiple call for each piece of information.
+ * <p>
+ * In this example, ({@link CustomerClientApp}) as as customer details consumer i.e. client to request for
+ * customer details to server.
+ * <p>
+ * CustomerResource ({@link CustomerResource}) act as server to serve customer information.
+ * And The CustomerDto ({@link CustomerDto} is data transfer object to share customer information.
+ */
+public class CustomerClientApp {
+
+  private static final Logger LOGGER = LoggerFactory.getLogger(CustomerClientApp.class);
+
+  /**
+   * Method as act client and request to server for details.
+   *
+   * @param args program argument.
+   */
+  public static void main(String[] args) {
+    List<CustomerDto> customers = new ArrayList<>();
+    CustomerDto customerOne = new CustomerDto("1", "Kelly", "Brown");
+    CustomerDto customerTwo = new CustomerDto("2", "Alfonso", "Bass");
+    customers.add(customerOne);
+    customers.add(customerTwo);
+
+    CustomerResource customerResource = new CustomerResource(customers);
+
+    LOGGER.info("All customers:-");
+    List<CustomerDto> allCustomers = customerResource.getAllCustomers();
+    printCustomerDetails(allCustomers);
+
+    LOGGER.info("----------------------------------------------------------");
+
+    LOGGER.info("Deleting customer with id {1}");
+    customerResource.delete(customerOne.getId());
+    allCustomers = customerResource.getAllCustomers();
+    printCustomerDetails(allCustomers);
+
+    LOGGER.info("----------------------------------------------------------");
+
+    LOGGER.info("Adding customer three}");
+    CustomerDto customerThree = new CustomerDto("3", "Lynda", "Blair");
+    customerResource.save(customerThree);
+    allCustomers = customerResource.getAllCustomers();
+    printCustomerDetails(allCustomers);
+  }
+
+  private static void printCustomerDetails(List<CustomerDto> allCustomers) {
+    allCustomers.forEach(customer -> LOGGER.info(customer.getFirstName()));
+  }
+}

data-transfer-object/src/main/java/com/iluwatar/datatransfer/CustomerDto.java

@@ -0,0 +1,60 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017 Gopinath Langote
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package com.iluwatar.datatransfer;
+
+/**
+ * {@link CustomerDto} is a data transfer object POJO. Instead of sending individual information to client
+ * We can send related information together in POJO.
+ * <p>
+ * Dto will not have any business logic in it.
+ */
+public class CustomerDto {
+  private final String id;
+  private final String firstName;
+  private final String lastName;
+
+  /**
+   * @param id        customer id
+   * @param firstName customer first name
+   * @param lastName  customer last name
+   */
+  public CustomerDto(String id, String firstName, String lastName) {
+    this.id = id;
+    this.firstName = firstName;
+    this.lastName = lastName;
+  }
+
+  public String getId() {
+    return id;
+  }
+
+  public String getFirstName() {
+    return firstName;
+  }
+
+  public String getLastName() {
+    return lastName;
+  }
+}

data-transfer-object/src/main/java/com/iluwatar/datatransfer/CustomerResource.java

@@ -0,0 +1,63 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017 Gopinath Langote
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package com.iluwatar.datatransfer;
+
+import java.util.List;
+
+/**
+ * The resource class which serves customer information.
+ * This class act as server in the demo. Which has all customer details.
+ */
+public class CustomerResource {
+  private List<CustomerDto> customers;
+
+  /**
+   * @param customers initialize resource with existing customers. Act as database.
+   */
+  public CustomerResource(List<CustomerDto> customers) {
+    this.customers = customers;
+  }
+
+  /**
+   * @return : all customers in list.
+   */
+  public List<CustomerDto> getAllCustomers() {
+    return customers;
+  }
+
+  /**
+   * @param customer save new customer to list.
+   */
+  public void save(CustomerDto customer) {
+    customers.add(customer);
+  }
+
+  /**
+   * @param customerId delete customer with id {@code customerId}
+   */
+  public void delete(String customerId) {
+    customers.removeIf(customer -> customer.getId().equals(customerId));
+  }
+}

data-transfer-object/src/test/java/com/iluwatar/datatransfer/CustomerResourceTest.java

@@ -0,0 +1,81 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017 Gopinath Langote
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package com.iluwatar.datatransfer;
+
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import static org.junit.Assert.assertEquals;
+
+/**
+ * tests {@link CustomerResource}.
+ */
+public class CustomerResourceTest {
+  @Test
+  public void shouldGetAllCustomers() {
+    CustomerDto customer = new CustomerDto("1", "Melody", "Yates");
+    List<CustomerDto> customers = new ArrayList<>();
+    customers.add(customer);
+
+    CustomerResource customerResource = new CustomerResource(customers);
+
+    List<CustomerDto> allCustomers = customerResource.getAllCustomers();
+
+    assertEquals(allCustomers.size(), 1);
+    assertEquals(allCustomers.get(0).getId(), "1");
+    assertEquals(allCustomers.get(0).getFirstName(), "Melody");
+    assertEquals(allCustomers.get(0).getLastName(), "Yates");
+  }
+
+  @Test
+  public void shouldSaveCustomer() {
+    CustomerDto customer = new CustomerDto("1", "Rita", "Reynolds");
+    CustomerResource customerResource = new CustomerResource(new ArrayList<>());
+
+    customerResource.save(customer);
+
+    List<CustomerDto> allCustomers = customerResource.getAllCustomers();
+    assertEquals(allCustomers.get(0).getId(), "1");
+    assertEquals(allCustomers.get(0).getFirstName(), "Rita");
+    assertEquals(allCustomers.get(0).getLastName(), "Reynolds");
+  }
+
+  @Test
+  public void shouldDeleteCustomer() {
+    CustomerDto customer = new CustomerDto("1", "Terry", "Nguyen");
+    List<CustomerDto> customers = new ArrayList<>();
+    customers.add(customer);
+
+    CustomerResource customerResource = new CustomerResource(customers);
+
+    customerResource.delete(customer.getId());
+
+    List<CustomerDto> allCustomers = customerResource.getAllCustomers();
+    assertEquals(allCustomers.size(), 0);
+  }
+
+}

decorator/README.md

@@ -19,7 +19,96 @@ Attach additional responsibilities to an object dynamically.
 Decorators provide a flexible alternative to subclassing for extending
 functionality.
 
-![alt text](./etc/decorator.png "Decorator")
+## Explanation
+
+Real world example
+
+> There is an angry troll living in the nearby hills. Usually it goes bare handed but sometimes it has a weapon. To arm the troll it's not necessary to create a new troll but to decorate it dynamically with a suitable weapon.
+
+In plain words
+
+> Decorator pattern lets you dynamically change the behavior of an object at run time by wrapping them in an object of a decorator class.
+
+Wikipedia says
+
+> In object-oriented programming, the decorator pattern is a design pattern that allows behavior to be added to an individual object, either statically or dynamically, without affecting the behavior of other objects from the same class. The decorator pattern is often useful for adhering to the Single Responsibility Principle, as it allows functionality to be divided between classes with unique areas of concern.
+
+**Programmatic Example**
+
+Lets take the troll example. First of all we have a simple troll implementing the troll interface
+
+```
+public interface Troll {
+  void attack();
+  int getAttackPower();
+  void fleeBattle();
+}
+
+public class SimpleTroll implements Troll {
+
+  private static final Logger LOGGER = LoggerFactory.getLogger(SimpleTroll.class);
+
+  @Override
+  public void attack() {
+    LOGGER.info("The troll tries to grab you!");
+  }
+
+  @Override
+  public int getAttackPower() {
+    return 10;
+  }
+
+  @Override
+  public void fleeBattle() {
+    LOGGER.info("The troll shrieks in horror and runs away!");
+  }
+}
+```
+
+Next we want to add club for the troll. We can do it dynamically by using a decorator
+
+```
+public class ClubbedTroll implements Troll {
+
+  private static final Logger LOGGER = LoggerFactory.getLogger(ClubbedTroll.class);
+
+  private Troll decorated;
+
+  public ClubbedTroll(Troll decorated) {
+    this.decorated = decorated;
+  }
+
+  @Override
+  public void attack() {
+    decorated.attack();
+    LOGGER.info("The troll swings at you with a club!");
+  }
+
+  @Override
+  public int getAttackPower() {
+    return decorated.getAttackPower() + 10;
+  }
+
+  @Override
+  public void fleeBattle() {
+    decorated.fleeBattle();
+  }
+}
+```
+
+Here's the troll in action
+
+```
+// simple troll
+Troll troll = new SimpleTroll();
+troll.attack(); // The troll tries to grab you!
+troll.fleeBattle(); // The troll shrieks in horror and runs away!
+
+// change the behavior of the simple troll by adding a decorator
+Troll clubbed = new ClubbedTroll(troll);
+clubbed.attack(); // The troll tries to grab you! The troll swings at you with a club!
+clubbed.fleeBattle(); // The troll shrieks in horror and runs away!
+```
 
 ## Applicability
 Use Decorator

decorator/etc/decorator.ucls

@@ -1,76 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<class-diagram version="1.1.11" icons="true" automaticImage="PNG" always-add-relationships="false" 
-  generalizations="true" realizations="true" associations="true" dependencies="false" nesting-relationships="true" 
-  router="FAN">  
-  <class id="1" language="java" name="com.iluwatar.decorator.App" project="decorator" 
-    file="/decorator/src/main/java/com/iluwatar/decorator/App.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="113" width="114" x="177" y="237"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </class>  
-  <class id="2" language="java" name="com.iluwatar.decorator.SimpleTroll" project="decorator" 
-    file="/decorator/src/main/java/com/iluwatar/decorator/SimpleTroll.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="149" width="125" x="496" y="237"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </class>  
-  <class id="3" language="java" name="com.iluwatar.decorator.ClubbedTroll" project="decorator" 
-    file="/decorator/src/main/java/com/iluwatar/decorator/ClubbedTroll.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="149" width="125" x="249" y="426"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </class>  
-  <class id="4" language="java" name="com.iluwatar.decorator.TrollDecorator" project="decorator" 
-    file="/decorator/src/main/java/com/iluwatar/decorator/TrollDecorator.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="149" width="125" x="331" y="237"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </class>  
-  <interface id="5" language="java" name="com.iluwatar.decorator.Troll" project="decorator" 
-    file="/decorator/src/main/java/com/iluwatar/decorator/Troll.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="113" width="125" x="414" y="426"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </interface>  
-  <realization id="6">    
-    <end type="SOURCE" refId="4"/>    
-    <end type="TARGET" refId="5"/>  
-  </realization>  
-  <generalization id="7">    
-    <end type="SOURCE" refId="3"/>    
-    <end type="TARGET" refId="4"/>  
-  </generalization>  
-  <realization id="8">    
-    <end type="SOURCE" refId="2"/>    
-    <end type="TARGET" refId="5"/>  
-  </realization>  
-  <association id="9">    
-    <end type="SOURCE" refId="4" navigable="false">      
-      <attribute id="10" name="decorated"/>      
-      <multiplicity id="11" minimum="0" maximum="1"/>    
-    </end>    
-    <end type="TARGET" refId="5" navigable="true"/>    
-    <display labels="true" multiplicity="true"/>  
-  </association>  
-  <classifier-display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-    sort-features="false" accessors="true" visibility="true">    
-    <attributes public="true" package="true" protected="true" private="true" static="true"/>    
-    <operations public="true" package="true" protected="true" private="true" static="true"/>  
-  </classifier-display>  
-  <association-display labels="true" multiplicity="true"/>
-</class-diagram>

decorator/etc/decorator.urm.puml

@@ -1,38 +0,0 @@
-@startuml
-package com.iluwatar.decorator {
-  class App {
-    - LOGGER : Logger {static}
-    + App()
-    + main(args : String[]) {static}
-  }
-  class ClubbedTroll {
-    - LOGGER : Logger {static}
-    + ClubbedTroll(decorated : Troll)
-    + attack()
-    + getAttackPower() : int
-  }
-  class SimpleTroll {
-    - LOGGER : Logger {static}
-    + SimpleTroll()
-    + attack()
-    + fleeBattle()
-    + getAttackPower() : int
-  }
-  interface Troll {
-    + attack() {abstract}
-    + fleeBattle() {abstract}
-    + getAttackPower() : int {abstract}
-  }
-  class TrollDecorator {
-    - decorated : Troll
-    + TrollDecorator(decorated : Troll)
-    + attack()
-    + fleeBattle()
-    + getAttackPower() : int
-  }
-}
-TrollDecorator -->  "-decorated" Troll
-ClubbedTroll --|> TrollDecorator 
-SimpleTroll ..|> Troll 
-TrollDecorator ..|> Troll 
-@enduml

decorator/src/main/java/com/iluwatar/decorator/ClubbedTroll.java

@@ -28,22 +28,29 @@ import org.slf4j.LoggerFactory;
 /**
  * Decorator that adds a club for the troll
  */
-public class ClubbedTroll extends TrollDecorator {
+public class ClubbedTroll implements Troll {
 
   private static final Logger LOGGER = LoggerFactory.getLogger(ClubbedTroll.class);
 
+  private Troll decorated;
+
   public ClubbedTroll(Troll decorated) {
-    super(decorated);
+    this.decorated = decorated;
   }
 
   @Override
   public void attack() {
-    super.attack();
+    decorated.attack();
     LOGGER.info("The troll swings at you with a club!");
   }
 
   @Override
   public int getAttackPower() {
-    return super.getAttackPower() + 10;
+    return decorated.getAttackPower() + 10;
+  }
+
+  @Override
+  public void fleeBattle() {
+    decorated.fleeBattle();
   }
 }

decorator/src/main/java/com/iluwatar/decorator/TrollDecorator.java

@@ -1,53 +0,0 @@
-/**
- * The MIT License
- * Copyright (c) 2014-2016 Ilkka Seppälä
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- * THE SOFTWARE.
- */
-package com.iluwatar.decorator;
-
-/**
- * TrollDecorator is a decorator for {@link Troll} objects. The calls to the {@link Troll} interface
- * are intercepted and decorated. Finally the calls are delegated to the decorated {@link Troll}
- * object.
- *
- */
-public class TrollDecorator implements Troll {
-
-  private Troll decorated;
-
-  public TrollDecorator(Troll decorated) {
-    this.decorated = decorated;
-  }
-
-  @Override
-  public void attack() {
-    decorated.attack();
-  }
-
-  @Override
-  public int getAttackPower() {
-    return decorated.getAttackPower();
-  }
-
-  @Override
-  public void fleeBattle() {
-    decorated.fleeBattle();
-  }
-}

decorator/src/test/java/com/iluwatar/decorator/ClubbedTrollTest.java

@@ -34,7 +34,7 @@ import static org.mockito.internal.verification.VerificationModeFactory.times;
 public class ClubbedTrollTest {
 
   @Test
-  public void testSmartHostile() throws Exception {
+  public void testClubbedTroll() throws Exception {
     // Create a normal troll first, but make sure we can spy on it later on.
     final Troll simpleTroll = spy(new SimpleTroll());
 

event-queue/README.md

@@ -11,7 +11,7 @@ tags:
 ---
 
 ## Intent
-Event Queue is a good pattern if You have a limited accesibility resource (for example: 
+Event Queue is a good pattern if You have a limited accessibility resource (for example: 
 Audio or Database), but You need to handle all the requests that want to use that.
 It puts all the requests in a queue and process them asynchronously.
 Gives the resource for the event when it is the next in the queue and in same time
@@ -22,7 +22,7 @@ removes it from the queue.
 ## Applicability
 Use the Event Queue pattern when
 
-* You have a limited accesibility resource and the asynchronous process is acceptable to reach that
+* You have a limited accessibility resource and the asynchronous process is acceptable to reach that
 
 ## Credits
 

event-sourcing/README.md

@@ -0,0 +1,33 @@
+---
+layout: pattern
+title: Event Sourcing
+folder: event-sourcing
+permalink: /patterns/event-sourcing/
+categories: Architectural
+tags:
+ - Java
+ - Difficulty Intermediate
+ - Performance
+---
+
+## Intent
+Instead of storing just the current state of the data in a domain, use an append-only store to record the full series of actions taken on that data. The store acts as the system of record and can be used to materialize the domain objects. This can simplify tasks in complex domains, by avoiding the need to synchronize the data model and the business domain, while improving performance, scalability, and responsiveness. It can also provide consistency for transactional data, and maintain full audit trails and history that can enable compensating actions.
+
+![alt text](./etc/event-sourcing.png "Event Sourcing")
+
+## Applicability
+Use the Event Sourcing pattern when
+
+* You need very high performance on persisting your application state even your application state have a complex relational data structure  
+* You need log of changes of your application state and ability to restore a state of any moment in time.
+* You need to debug production problems by replaying the past events. 
+
+## Real world examples
+
+* [The Lmax Architecture] (https://martinfowler.com/articles/lmax.html)
+
+## Credits
+
+* [Martin Fowler - Event Sourcing] (https://martinfowler.com/eaaDev/EventSourcing.html)
+* [Event Sourcing | Microsoft Docs] (https://docs.microsoft.com/en-us/azure/architecture/patterns/event-sourcing)
+* [Reference 3: Introducing Event Sourcing] (https://msdn.microsoft.com/en-us/library/jj591559.aspx)

event-sourcing/etc/event-sourcing.ucls

@@ -1,111 +1,117 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<class-diagram version="1.1.8" icons="true" automaticImage="PNG" always-add-relationships="false" generalizations="true" 
+<class-diagram version="1.2.0" icons="true" automaticImage="PNG" always-add-relationships="true" generalizations="true" 
-  realizations="true" associations="true" dependencies="false" nesting-relationships="true">  
+  realizations="true" associations="true" dependencies="false" nesting-relationships="true" router="FAN">  
-  <class id="1" language="java" name="com.iluwatar.factory.method.OrcBlacksmith" project="factory-method" 
+  <class id="1" language="java" name="com.iluwatar.event.sourcing.event.DomainEvent" project="event-sourcing" 
-    file="/factory-method/src/main/java/com/iluwatar/factory/method/OrcBlacksmith.java" binary="false" 
+    file="/event-sourcing/src/main/java/com/iluwatar/event/sourcing/event/DomainEvent.java" binary="false" 
     corner="BOTTOM_RIGHT">    
-    <position height="106" width="280" x="-46" y="239"/>    
+    <position height="-1" width="-1" x="809" y="161"/>    
     <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
       sort-features="false" accessors="true" visibility="true">      
       <attributes public="true" package="true" protected="true" private="true" static="true"/>      
       <operations public="true" package="true" protected="true" private="true" static="true"/>    
     </display>  
   </class>  
-  <interface id="2" language="java" name="com.iluwatar.factory.method.Blacksmith" project="factory-method" 
+  <class id="2" language="java" name="com.iluwatar.event.sourcing.event.AccountCreateEvent" project="event-sourcing" 
-    file="/factory-method/src/main/java/com/iluwatar/factory/method/Blacksmith.java" binary="false" 
+    file="/event-sourcing/src/main/java/com/iluwatar/event/sourcing/event/AccountCreateEvent.java" binary="false" 
     corner="BOTTOM_RIGHT">    
-    <position height="88" width="280" x="114" y="385"/>    
+    <position height="-1" width="-1" x="145" y="455"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </interface>  
-  <enumeration id="3" language="java" name="com.iluwatar.factory.method.WeaponType" project="factory-method" 
-    file="/factory-method/src/main/java/com/iluwatar/factory/method/WeaponType.java" binary="false" 
-    corner="BOTTOM_RIGHT">    
-    <position height="196" width="210" x="793" y="385"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </enumeration>  
-  <class id="4" language="java" name="com.iluwatar.factory.method.OrcWeapon" project="factory-method" 
-    file="/factory-method/src/main/java/com/iluwatar/factory/method/OrcWeapon.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="106" width="178" x="806" y="239"/>    
     <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
       sort-features="false" accessors="true" visibility="true">      
       <attributes public="true" package="true" protected="true" private="true" static="true"/>      
       <operations public="true" package="true" protected="true" private="true" static="true"/>    
     </display>  
   </class>  
-  <class id="5" language="java" name="com.iluwatar.factory.method.ElfWeapon" project="factory-method" 
+  <class id="3" language="java" name="com.iluwatar.event.sourcing.event.MoneyDepositEvent" project="event-sourcing" 
-    file="/factory-method/src/main/java/com/iluwatar/factory/method/ElfWeapon.java" binary="false" corner="BOTTOM_RIGHT">    
+    file="/event-sourcing/src/main/java/com/iluwatar/event/sourcing/event/MoneyDepositEvent.java" binary="false" 
-    <position height="106" width="172" x="594" y="239"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </class>  
-  <interface id="6" language="java" name="com.iluwatar.factory.method.Weapon" project="factory-method" 
-    file="/factory-method/src/main/java/com/iluwatar/factory/method/Weapon.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="70" width="159" x="594" y="385"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </interface>  
-  <class id="7" language="java" name="com.iluwatar.factory.method.ElfBlacksmith" project="factory-method" 
-    file="/factory-method/src/main/java/com/iluwatar/factory/method/ElfBlacksmith.java" binary="false" 
     corner="BOTTOM_RIGHT">    
-    <position height="106" width="280" x="274" y="239"/>    
+    <position height="-1" width="-1" x="480" y="451"/>    
     <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
       sort-features="false" accessors="true" visibility="true">      
       <attributes public="true" package="true" protected="true" private="true" static="true"/>      
       <operations public="true" package="true" protected="true" private="true" static="true"/>    
     </display>  
   </class>  
-  <realization id="8">    
+  <class id="4" language="java" name="com.iluwatar.event.sourcing.event.MoneyTransferEvent" project="event-sourcing" 
+    file="/event-sourcing/src/main/java/com/iluwatar/event/sourcing/event/MoneyTransferEvent.java" binary="false" 
+    corner="BOTTOM_RIGHT">    
+    <position height="-1" width="-1" x="809" y="472"/>    
+    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
+      sort-features="false" accessors="true" visibility="true">      
+      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
+      <operations public="true" package="true" protected="true" private="true" static="true"/>    
+    </display>  
+  </class>  
+  <class id="5" language="java" name="com.iluwatar.event.sourcing.state.AccountAggregate" project="event-sourcing" 
+    file="/event-sourcing/src/main/java/com/iluwatar/event/sourcing/state/AccountAggregate.java" binary="false" 
+    corner="BOTTOM_RIGHT">    
+    <position height="-1" width="-1" x="104" y="826"/>    
+    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
+      sort-features="false" accessors="true" visibility="true">      
+      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
+      <operations public="true" package="true" protected="true" private="true" static="true"/>    
+    </display>  
+  </class>  
+  <class id="6" language="java" name="com.iluwatar.event.sourcing.processor.DomainEventProcessor" 
+    project="event-sourcing" 
+    file="/event-sourcing/src/main/java/com/iluwatar/event/sourcing/processor/DomainEventProcessor.java" binary="false" 
+    corner="BOTTOM_RIGHT">    
+    <position height="-1" width="-1" x="458" y="121"/>    
+    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
+      sort-features="false" accessors="true" visibility="true">      
+      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
+      <operations public="true" package="true" protected="true" private="true" static="true"/>    
+    </display>  
+  </class>  
+  <class id="7" language="java" name="com.iluwatar.event.sourcing.processor.JsonFileJournal" project="event-sourcing" 
+    file="/event-sourcing/src/main/java/com/iluwatar/event/sourcing/processor/JsonFileJournal.java" binary="false" 
+    corner="BOTTOM_RIGHT">    
+    <position height="189" width="171" x="69" y="26"/>    
+    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
+      sort-features="false" accessors="true" visibility="true">      
+      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
+      <operations public="true" package="true" protected="true" private="true" static="true"/>    
+    </display>  
+  </class>  
+  <class id="8" language="java" name="com.iluwatar.event.sourcing.domain.Account" project="event-sourcing" 
+    file="/event-sourcing/src/main/java/com/iluwatar/event/sourcing/domain/Account.java" binary="false" 
+    corner="BOTTOM_RIGHT">    
+    <position height="-1" width="-1" x="472" y="827"/>    
+    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
+      sort-features="false" accessors="true" visibility="true">      
+      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
+      <operations public="true" package="true" protected="true" private="true" static="true"/>    
+    </display>  
+  </class>  
+  <generalization id="9">    
+    <end type="SOURCE" refId="2"/>    
+    <end type="TARGET" refId="1"/>  
+  </generalization>  
+  <generalization id="10">    
     <end type="SOURCE" refId="4"/>    
-    <end type="TARGET" refId="6"/>  
+    <end type="TARGET" refId="1"/>  
-  </realization>  
+  </generalization>  
-  <realization id="9">    
-    <end type="SOURCE" refId="7"/>    
-    <end type="TARGET" refId="2"/>  
-  </realization>  
-  <realization id="10">    
-    <end type="SOURCE" refId="5"/>    
-    <end type="TARGET" refId="6"/>  
-  </realization>  
   <association id="11">    
-    <end type="SOURCE" refId="4" navigable="false">      
+    <end type="SOURCE" refId="6" navigable="false">      
-      <attribute id="12" name="weaponType">        
+      <attribute id="12" name="processorJournal">        
         <position height="0" width="0" x="0" y="0"/>      
       </attribute>      
       <multiplicity id="13" minimum="0" maximum="1">        
         <position height="0" width="0" x="0" y="0"/>      
       </multiplicity>    
     </end>    
-    <end type="TARGET" refId="3" navigable="true"/>    
+    <end type="TARGET" refId="7" navigable="true"/>    
     <display labels="true" multiplicity="true"/>  
   </association>  
-  <realization id="14">    
+  <generalization id="14">    
-    <end type="SOURCE" refId="1"/>    
+    <end type="SOURCE" refId="3"/>    
-    <end type="TARGET" refId="2"/>  
+    <end type="TARGET" refId="1"/>  
-  </realization>  
+  </generalization>  
   <association id="15">    
     <end type="SOURCE" refId="5" navigable="false">      
-      <attribute id="16" name="weaponType">        
+      <attribute id="16" name="accounts"/>      
-        <position height="0" width="0" x="0" y="0"/>      
+      <multiplicity id="17" minimum="0" maximum="2147483647"/>    
-      </attribute>      
-      <multiplicity id="17" minimum="0" maximum="1">        
-        <position height="0" width="0" x="0" y="0"/>      
-      </multiplicity>    
     </end>    
-    <end type="TARGET" refId="3" navigable="true"/>    
+    <end type="TARGET" refId="8" navigable="true"/>    
     <display labels="true" multiplicity="true"/>  
   </association>  
   <classifier-display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 

event-sourcing/etc/event-sourcing.urm.puml

@@ -0,0 +1,184 @@
+@startuml
+package com.iluwatar.event.sourcing.journal {
+  class JsonFileJournal {
+    - aFile : File
+    - events : List<String>
+    - index : int
+    + JsonFileJournal()
+    + readNext() : DomainEvent
+    + reset()
+    + write(domainEvent : DomainEvent)
+  }
+}
+package com.iluwatar.event.sourcing.processor {
+  class DomainEventProcessor {
+    - precessorJournal : ProcessorJournal
+    + DomainEventProcessor()
+    + process(domainEvent : DomainEvent)
+    + recover()
+    + setPrecessorJournal(precessorJournal : ProcessorJournal)
+  }
+}
+package com.iluwatar.event.sourcing.service {
+  class AccountService {
+    - eventProcessor : EventProcessor
+    + AccountService(eventProcessor : EventProcessor)
+    + createAccount(accountNo : int, owner : String)
+  }
+  class MoneyTransactionService {
+    - eventProcessor : EventProcessor
+    + MoneyTransactionService(eventProcessor : EventProcessor)
+    + depositMoney(accountNo : int, money : BigDecimal)
+    + transferMoney(accountNoFrom : int, accountNoTo : int, money : BigDecimal)
+    + withdrawalMoney(accountNo : int, money : BigDecimal)
+  }
+  class SequenceIdGenerator {
+    - sequenceId : long {static}
+    + SequenceIdGenerator()
+    + nextSequenceId() : long {static}
+  }
+}
+package com.iluwatar.event.sourcing.event {
+  class AccountCreateEvent {
+    - accountNo : int
+    - owner : String
+    + AccountCreateEvent(sequenceId : long, createdTime : long, accountNo : int, owner : String)
+    + getAccountNo() : int
+    + getOwner() : String
+    + process()
+  }
+  class MoneyDepositEvent {
+    - accountNo : int
+    - money : BigDecimal
+    + MoneyDepositEvent(sequenceId : long, createdTime : long, accountNo : int, money : BigDecimal)
+    + getAccountNo() : int
+    + getMoney() : BigDecimal
+    + process()
+  }
+  class MoneyTransferEvent {
+    - accountNoFrom : int
+    - accountNoTo : int
+    - money : BigDecimal
+    + MoneyTransferEvent(sequenceId : long, createdTime : long, money : BigDecimal, accountNoFrom : int, accountNoTo : int)
+    + getAccountNoFrom() : int
+    + getAccountNoTo() : int
+    + getMoney() : BigDecimal
+    + process()
+  }
+  class MoneyWithdrawalEvent {
+    - accountNo : int
+    - money : BigDecimal
+    + MoneyWithdrawalEvent(sequenceId : long, createdTime : long, accountNo : int, money : BigDecimal)
+    + getAccountNo() : int
+    + getMoney() : BigDecimal
+    + process()
+  }
+}
+package com.iluwatar.event.sourcing.gateway {
+  class AccountCreateContractSender {
+    + AccountCreateContractSender()
+    + sendContractInfo(account : Account)
+  }
+  class Gateways {
+    - accountCreateContractSender : AccountCreateContractSender {static}
+    - transactionLogger : TransactionLogger {static}
+    + Gateways()
+    + getAccountCreateContractSender() : AccountCreateContractSender {static}
+    + getTransactionLogger() : TransactionLogger {static}
+  }
+  class TransactionLogger {
+    + TransactionLogger()
+    + log(transaction : Transaction)
+  }
+}
+package com.iluwatar.event.sourcing.app {
+  class App {
+    + App()
+    + main(args : String[]) {static}
+  }
+}
+package com.iluwatar.event.sourcing.state {
+  class AccountAggregate {
+    - accounts : Map<Integer, Account> {static}
+    + AccountAggregate()
+    + getAccount(accountNo : int) : Account {static}
+    + putAccount(account : Account) {static}
+    + resetState() {static}
+  }
+}
+package com.iluwatar.event.sourcing.domain {
+  class Account {
+    - accountNo : int
+    - money : BigDecimal
+    - owner : String
+    - transactions : List<Transaction>
+    + Account(accountNo : int, owner : String)
+    + copy() : Account
+    - depositMoney(money : BigDecimal) : Transaction
+    + getAccountNo() : int
+    + getMoney() : BigDecimal
+    + getOwner() : String
+    + getTransactions() : List<Transaction>
+    - handleDeposit(money : BigDecimal, realTime : boolean)
+    + handleEvent(accountCreateEvent : AccountCreateEvent)
+    + handleEvent(moneyDepositEvent : MoneyDepositEvent)
+    + handleEvent(moneyWithdrawalEvent : MoneyWithdrawalEvent)
+    + handleTransferFromEvent(moneyTransferEvent : MoneyTransferEvent)
+    + handleTransferToEvent(moneyTransferEvent : MoneyTransferEvent)
+    - handleWithdrawal(money : BigDecimal, realTime : boolean)
+    + setMoney(money : BigDecimal)
+    + setTransactions(transactions : List<Transaction>)
+    + toString() : String
+    - withdrawMoney(money : BigDecimal) : Transaction
+  }
+  class Transaction {
+    - accountNo : int
+    - lastBalance : BigDecimal
+    - moneyIn : BigDecimal
+    - moneyOut : BigDecimal
+    + Transaction(accountNo : int, moneyIn : BigDecimal, moneyOut : BigDecimal, lastBalance : BigDecimal)
+    + getAccountNo() : int
+    + getLastBalance() : BigDecimal
+    + getMoneyIn() : BigDecimal
+    + getMoneyOut() : BigDecimal
+    + toString() : String
+  }
+}
+package com.iluwatar.event.sourcing.api {
+  abstract class DomainEvent {
+    - createdTime : long
+    - eventClassName : String
+    - realTime : boolean
+    - sequenceId : long
+    + DomainEvent(sequenceId : long, createdTime : long, eventClassName : String)
+    + getCreatedTime() : long
+    + getEventClassName() : String
+    + getSequenceId() : long
+    + isRealTime() : boolean
+    + process() {abstract}
+    + setRealTime(realTime : boolean)
+  }
+  interface EventProcessor {
+    + process(DomainEvent) {abstract}
+    + recover() {abstract}
+    + setPrecessorJournal(ProcessorJournal) {abstract}
+  }
+  interface ProcessorJournal {
+    + readNext() : DomainEvent {abstract}
+    + reset() {abstract}
+    + write(DomainEvent) {abstract}
+  }
+}
+Gateways -->  "-accountCreateContractSender" AccountCreateContractSender
+DomainEventProcessor -->  "-precessorJournal" ProcessorJournal
+Account -->  "-transactions" Transaction
+Gateways -->  "-transactionLogger" TransactionLogger
+AccountService -->  "-eventProcessor" EventProcessor
+MoneyTransactionService -->  "-eventProcessor" EventProcessor
+AccountCreateEvent --|> DomainEvent 
+MoneyDepositEvent --|> DomainEvent 
+MoneyTransferEvent --|> DomainEvent 
+MoneyWithdrawalEvent --|> DomainEvent 
+JsonFileJournal ..|> ProcessorJournal 
+DomainEventProcessor ..|> EventProcessor 
+@enduml

event-sourcing/pom.xml

@@ -0,0 +1,50 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+
+    The MIT License
+    Copyright (c) 2014-2016 Ilkka Sepp<70>l<EFBFBD>
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to deal
+    in the Software without restriction, including without limitation the rights
+    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+    copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in
+    all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+    THE SOFTWARE.
+
+-->
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+  <parent>
+    <artifactId>java-design-patterns</artifactId>
+    <groupId>com.iluwatar</groupId>
+    <version>1.17.0-SNAPSHOT</version>
+  </parent>
+  <artifactId>event-sourcing</artifactId>
+  <dependencies>
+    <dependency>
+      <groupId>junit</groupId>
+      <artifactId>junit</artifactId>
+      <scope>test</scope>
+    </dependency>
+    <!-- https://mvnrepository.com/artifact/com.google.code.gson/gson -->
+    <dependency>
+      <groupId>com.google.code.gson</groupId>
+      <artifactId>gson</artifactId>
+      <version>2.8.1</version>
+    </dependency>
+
+  </dependencies>
+</project>

event-sourcing/src/main/java/com/iluwatar/event/sourcing/app/App.java

@@ -0,0 +1,115 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.event.sourcing.app;
+
+import com.iluwatar.event.sourcing.event.AccountCreateEvent;
+import com.iluwatar.event.sourcing.event.MoneyDepositEvent;
+import com.iluwatar.event.sourcing.event.MoneyTransferEvent;
+import com.iluwatar.event.sourcing.processor.DomainEventProcessor;
+import com.iluwatar.event.sourcing.state.AccountAggregate;
+import java.math.BigDecimal;
+import java.util.Date;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Event Sourcing : Instead of storing just the current state of the data in a domain, use an
+ * append-only store to record the full series of actions taken on that data. The store acts as the
+ * system of record and can be used to materialize the domain objects. This can simplify tasks in
+ * complex domains, by avoiding the need to synchronize the data model and the business domain,
+ * while improving performance, scalability, and responsiveness. It can also provide consistency for
+ * transactional data, and maintain full audit trails and history that can enable compensating
+ * actions.
+ *
+ * This App class is an example usage of Event Sourcing pattern. As an example, two bank account is
+ * created, then some money deposit and transfer actions are taken so a new state of accounts is
+ * created. At that point, state is cleared in order to represent a system shot down. After the shot
+ * down, system state is recovered by re-creating the past events from event journal. Then state is
+ * printed so a user can view the last state is same with the state before system shot down.
+ *
+ * Created by Serdar Hamzaogullari on 06.08.2017.
+ */
+public class App {
+
+  private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
+  /**
+   * The constant ACCOUNT OF DAENERYS.
+   */
+  public static final int ACCOUNT_OF_DAENERYS = 1;
+  /**
+   * The constant ACCOUNT OF JON.
+   */
+  public static final int ACCOUNT_OF_JON = 2;
+
+  /**
+   * The entry point of application.
+   *
+   * @param args the input arguments
+   */
+  public static void main(String[] args) {
+
+    DomainEventProcessor eventProcessor = new DomainEventProcessor();
+
+
+    LOGGER.info("Running the system first time............");
+    eventProcessor.reset();
+
+    LOGGER.info("Creating th accounts............");
+
+    eventProcessor.process(new AccountCreateEvent(
+        0, new Date().getTime(), ACCOUNT_OF_DAENERYS, "Daenerys Targaryen"));
+
+    eventProcessor.process(new AccountCreateEvent(
+        1, new Date().getTime(), ACCOUNT_OF_JON, "Jon Snow"));
+
+    LOGGER.info("Do some money operations............");
+
+    eventProcessor.process(new MoneyDepositEvent(
+        2, new Date().getTime(), ACCOUNT_OF_DAENERYS,  new BigDecimal("100000")));
+
+    eventProcessor.process(new MoneyDepositEvent(
+        3, new Date().getTime(), ACCOUNT_OF_JON,  new BigDecimal("100")));
+
+    eventProcessor.process(new MoneyTransferEvent(
+        4, new Date().getTime(), new BigDecimal("10000"), ACCOUNT_OF_DAENERYS,
+        ACCOUNT_OF_JON));
+
+    LOGGER.info("...............State:............");
+    LOGGER.info(AccountAggregate.getAccount(ACCOUNT_OF_DAENERYS).toString());
+    LOGGER.info(AccountAggregate.getAccount(ACCOUNT_OF_JON).toString());
+
+    LOGGER.info("At that point system had a shot down, state in memory is cleared............");
+    AccountAggregate.resetState();
+
+    LOGGER.info("Recover the system by the events in journal file............");
+
+    eventProcessor = new DomainEventProcessor();
+    eventProcessor.recover();
+
+    LOGGER.info("...............Recovered State:............");
+    LOGGER.info(AccountAggregate.getAccount(ACCOUNT_OF_DAENERYS).toString());
+    LOGGER.info(AccountAggregate.getAccount(ACCOUNT_OF_JON).toString());
+  }
+
+
+}

event-sourcing/src/main/java/com/iluwatar/event/sourcing/domain/Account.java

@@ -0,0 +1,186 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.event.sourcing.domain;
+
+import com.iluwatar.event.sourcing.event.AccountCreateEvent;
+import com.iluwatar.event.sourcing.event.MoneyDepositEvent;
+import com.iluwatar.event.sourcing.event.MoneyTransferEvent;
+import com.iluwatar.event.sourcing.state.AccountAggregate;
+import java.math.BigDecimal;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * This is the Account class that holds the account info, the account number,
+ * account owner name and money of the account. Account class also have the business logic of events
+ * that effects this account.
+ *
+ * Created by Serdar Hamzaogullari on 06.08.2017.
+ */
+public class Account {
+
+  private static final Logger LOGGER = LoggerFactory.getLogger(Account.class);
+
+  private final int accountNo;
+  private final String owner;
+  private BigDecimal money;
+
+  /**
+   * Instantiates a new Account.
+   *
+   * @param accountNo the account no
+   * @param owner the owner
+   */
+  public Account(int accountNo, String owner) {
+    this.accountNo = accountNo;
+    this.owner = owner;
+    money = BigDecimal.ZERO;
+  }
+
+  /**
+   * Gets account no.
+   *
+   * @return the account no
+   */
+  public int getAccountNo() {
+    return accountNo;
+  }
+
+  /**
+   * Gets owner.
+   *
+   * @return the owner
+   */
+  public String getOwner() {
+    return owner;
+  }
+
+  /**
+   * Gets money.
+   *
+   * @return the money
+   */
+  public BigDecimal getMoney() {
+    return money;
+  }
+
+  /**
+   * Sets money.
+   *
+   * @param money the money
+   */
+  public void setMoney(BigDecimal money) {
+    this.money = money;
+  }
+
+
+  /**
+   * Copy account.
+   *
+   * @return the account
+   */
+  public Account copy() {
+    Account account = new Account(accountNo, owner);
+    account.setMoney(money);
+    return account;
+  }
+
+  @Override
+  public String toString() {
+    return "Account{"
+        + "accountNo=" + accountNo
+        + ", owner='" + owner + '\''
+        + ", money=" + money
+        + '}';
+  }
+
+  private void depositMoney(BigDecimal money) {
+    this.money = this.money.add(money);
+  }
+
+  private void withdrawMoney(BigDecimal money) {
+    this.money = this.money.subtract(money);
+  }
+
+  private void handleDeposit(BigDecimal money, boolean realTime) {
+    depositMoney(money);
+    AccountAggregate.putAccount(this);
+    if (realTime) {
+      LOGGER.info("Some external api for only realtime execution could be called here.");
+    }
+  }
+
+  private void handleWithdrawal(BigDecimal money, boolean realTime) {
+    if (this.money.compareTo(money) == -1) {
+      throw new RuntimeException("Insufficient Account Balance");
+    }
+
+    withdrawMoney(money);
+    AccountAggregate.putAccount(this);
+    if (realTime) {
+      LOGGER.info("Some external api for only realtime execution could be called here.");
+    }
+  }
+
+  /**
+   * Handles the MoneyDepositEvent.
+   *
+   * @param moneyDepositEvent the money deposit event
+   */
+  public void handleEvent(MoneyDepositEvent moneyDepositEvent) {
+    handleDeposit(moneyDepositEvent.getMoney(), moneyDepositEvent.isRealTime());
+  }
+
+
+  /**
+   * Handles the AccountCreateEvent.
+   *
+   * @param accountCreateEvent the account create event
+   */
+  public void handleEvent(AccountCreateEvent accountCreateEvent) {
+    AccountAggregate.putAccount(this);
+    if (accountCreateEvent.isRealTime()) {
+      LOGGER.info("Some external api for only realtime execution could be called here.");
+    }
+  }
+
+  /**
+   * Handles transfer from account event.
+   *
+   * @param moneyTransferEvent the money transfer event
+   */
+  public void handleTransferFromEvent(MoneyTransferEvent moneyTransferEvent) {
+    handleWithdrawal(moneyTransferEvent.getMoney(), moneyTransferEvent.isRealTime());
+  }
+
+  /**
+   * Handles transfer to account event.
+   *
+   * @param moneyTransferEvent the money transfer event
+   */
+  public void handleTransferToEvent(MoneyTransferEvent moneyTransferEvent) {
+    handleDeposit(moneyTransferEvent.getMoney(), moneyTransferEvent.isRealTime());
+  }
+
+
+}

event-sourcing/src/main/java/com/iluwatar/event/sourcing/event/AccountCreateEvent.java

@@ -0,0 +1,82 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.event.sourcing.event;
+
+import com.iluwatar.event.sourcing.domain.Account;
+import com.iluwatar.event.sourcing.state.AccountAggregate;
+
+/**
+ * This is the class that implements account create event.
+ * Holds the necessary info for an account create event.
+ * Implements the process function that finds the event related
+ * domain objects and calls the related domain object's handle event functions
+ *
+ * Created by Serdar Hamzaogullari on 06.08.2017.
+ */
+public class AccountCreateEvent extends DomainEvent {
+
+  private final int accountNo;
+  private final String owner;
+
+  /**
+   * Instantiates a new Account create event.
+   *
+   * @param sequenceId the sequence id
+   * @param createdTime the created time
+   * @param accountNo the account no
+   * @param owner the owner
+   */
+  public AccountCreateEvent(long sequenceId, long createdTime, int accountNo, String owner) {
+    super(sequenceId, createdTime, "AccountCreateEvent");
+    this.accountNo = accountNo;
+    this.owner = owner;
+  }
+
+  /**
+   * Gets account no.
+   *
+   * @return the account no
+   */
+  public int getAccountNo() {
+    return accountNo;
+  }
+
+  /**
+   * Gets owner.
+   *
+   * @return the owner
+   */
+  public String getOwner() {
+    return owner;
+  }
+
+  @Override
+  public void process() {
+    Account account = AccountAggregate.getAccount(accountNo);
+    if (account != null) {
+      throw new RuntimeException("Account already exists");
+    }
+    account = new Account(accountNo, owner);
+    account.handleEvent(this);
+  }
+}

event-sourcing/src/main/java/com/iluwatar/event/sourcing/event/DomainEvent.java

@@ -0,0 +1,101 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.event.sourcing.event;
+
+import java.io.Serializable;
+
+/**
+ * This is the base class for domain events. All events must extend this class.
+ *
+ * Created by Serdar Hamzaogullari on 06.08.2017.
+ */
+public abstract class DomainEvent implements Serializable {
+
+  private final long sequenceId;
+  private final long createdTime;
+  private final String eventClassName;
+  private boolean realTime = true;
+
+  /**
+   * Instantiates a new Domain event.
+   *
+   * @param sequenceId the sequence id
+   * @param createdTime the created time
+   * @param eventClassName the event class name
+   */
+  public DomainEvent(long sequenceId, long createdTime, String eventClassName) {
+    this.sequenceId = sequenceId;
+    this.createdTime = createdTime;
+    this.eventClassName = eventClassName;
+  }
+
+  /**
+   * Gets sequence id.
+   *
+   * @return the sequence id
+   */
+  public long getSequenceId() {
+    return sequenceId;
+  }
+
+  /**
+   * Gets created time.
+   *
+   * @return the created time
+   */
+  public long getCreatedTime() {
+    return createdTime;
+  }
+
+  /**
+   * Is real time boolean.
+   *
+   * @return the boolean
+   */
+  public boolean isRealTime() {
+    return realTime;
+  }
+
+  /**
+   * Sets real time.
+   *
+   * @param realTime the real time
+   */
+  public void setRealTime(boolean realTime) {
+    this.realTime = realTime;
+  }
+
+  /**
+   * Process.
+   */
+  public abstract void process();
+
+  /**
+   * Gets event class name.
+   *
+   * @return the event class name
+   */
+  public String getEventClassName() {
+    return eventClassName;
+  }
+}

event-sourcing/src/main/java/com/iluwatar/event/sourcing/event/MoneyDepositEvent.java

@@ -0,0 +1,82 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.event.sourcing.event;
+
+import com.iluwatar.event.sourcing.domain.Account;
+import com.iluwatar.event.sourcing.state.AccountAggregate;
+import java.math.BigDecimal;
+
+/**
+ * This is the class that implements money deposit event.
+ * Holds the necessary info for a money deposit event.
+ * Implements the process function that finds the event related
+ * domain objects and calls the related domain object's handle event functions
+ *
+ * Created by Serdar Hamzaogullari on 06.08.2017.
+ */
+public class MoneyDepositEvent extends DomainEvent {
+
+  private final BigDecimal money;
+  private final int accountNo;
+
+  /**
+   * Instantiates a new Money deposit event.
+   *
+   * @param sequenceId the sequence id
+   * @param createdTime the created time
+   * @param accountNo the account no
+   * @param money the money
+   */
+  public MoneyDepositEvent(long sequenceId, long createdTime, int accountNo, BigDecimal money) {
+    super(sequenceId, createdTime, "MoneyDepositEvent");
+    this.money = money;
+    this.accountNo = accountNo;
+  }
+
+  /**
+   * Gets money.
+   *
+   * @return the money
+   */
+  public BigDecimal getMoney() {
+    return money;
+  }
+
+  /**
+   * Gets account no.
+   *
+   * @return the account no
+   */
+  public int getAccountNo() {
+    return accountNo;
+  }
+
+  @Override
+  public void process() {
+    Account account = AccountAggregate.getAccount(accountNo);
+    if (account == null) {
+      throw new RuntimeException("Account not found");
+    }
+    account.handleEvent(this);
+  }
+}

event-sourcing/src/main/java/com/iluwatar/event/sourcing/event/MoneyTransferEvent.java

@@ -0,0 +1,101 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.event.sourcing.event;
+
+import com.iluwatar.event.sourcing.domain.Account;
+import com.iluwatar.event.sourcing.state.AccountAggregate;
+import java.math.BigDecimal;
+
+/**
+ * This is the class that implements money transfer event.
+ * Holds the necessary info for a money transfer event.
+ * Implements the process function that finds the event related
+ * domain objects and calls the related domain object's handle event functions
+ *
+ * Created by Serdar Hamzaogullari on 06.08.2017.
+ */
+public class MoneyTransferEvent extends DomainEvent {
+
+  private final BigDecimal money;
+  private final int accountNoFrom;
+  private final int accountNoTo;
+
+  /**
+   * Instantiates a new Money transfer event.
+   *
+   * @param sequenceId the sequence id
+   * @param createdTime the created time
+   * @param money the money
+   * @param accountNoFrom the account no from
+   * @param accountNoTo the account no to
+   */
+  public MoneyTransferEvent(long sequenceId, long createdTime, BigDecimal money, int accountNoFrom,
+      int accountNoTo) {
+    super(sequenceId, createdTime, "MoneyTransferEvent");
+    this.money = money;
+    this.accountNoFrom = accountNoFrom;
+    this.accountNoTo = accountNoTo;
+  }
+
+  /**
+   * Gets money.
+   *
+   * @return the money
+   */
+  public BigDecimal getMoney() {
+    return money;
+  }
+
+  /**
+   * Gets account no which the money comes from.
+   *
+   * @return the account no from
+   */
+  public int getAccountNoFrom() {
+    return accountNoFrom;
+  }
+
+  /**
+   * Gets account no which the money goes to.
+   *
+   * @return the account no to
+   */
+  public int getAccountNoTo() {
+    return accountNoTo;
+  }
+
+  @Override
+  public void process() {
+    Account accountFrom = AccountAggregate.getAccount(accountNoFrom);
+    if (accountFrom == null) {
+      throw new RuntimeException("Account not found " + accountNoFrom);
+    }
+    Account accountTo = AccountAggregate.getAccount(accountNoTo);
+    if (accountTo == null) {
+      throw new RuntimeException("Account not found" + accountTo);
+    }
+
+    accountFrom.handleTransferFromEvent(this);
+    accountTo.handleTransferToEvent(this);
+  }
+}

event-sourcing/src/main/java/com/iluwatar/event/sourcing/processor/DomainEventProcessor.java

@@ -1,6 +1,6 @@
 /**
  * The MIT License
- * Copyright (c) 2014-2016 Ilkka Seppälä
+ * Copyright (c) 2014 Ilkka Seppälä
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -20,36 +20,50 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
-package com.iluwatar.bridge;
+package com.iluwatar.event.sourcing.processor;
 
-import org.junit.Test;
+import com.iluwatar.event.sourcing.event.DomainEvent;
-
-import static org.mockito.Mockito.spy;
-import static org.mockito.Mockito.verify;
-import static org.mockito.Mockito.verifyNoMoreInteractions;
-import static org.mockito.internal.verification.VerificationModeFactory.times;
 
 /**
- * Date: 12/6/15 - 11:15 PM
+ * This is the implementation of event processor.
+ * All events are processed by this class.
+ * This processor uses processorJournal to persist and recover events.
  *
- * @author Jeroen Meulemeester
+ * Created by Serdar Hamzaogullari on 06.08.2017.
  */
-public class BlindingMagicWeaponTest extends MagicWeaponTest {
+public class DomainEventProcessor {
+
+  private final JsonFileJournal processorJournal = new JsonFileJournal();
 
   /**
-   * Invoke all possible actions on the weapon and check if the actions are executed on the actual
+   * Process.
-   * underlying weapon implementation.
+   *
+   * @param domainEvent the domain event
    */
-  @Test
+  public void process(DomainEvent domainEvent) {
-  public void testExcalibur() throws Exception {
+    domainEvent.process();
-    final Excalibur excalibur = spy(new Excalibur());
+    processorJournal.write(domainEvent);
-    final BlindingMagicWeapon blindingMagicWeapon = new BlindingMagicWeapon(excalibur);
-
-    testBasicWeaponActions(blindingMagicWeapon, excalibur);
-
-    blindingMagicWeapon.blind();
-    verify(excalibur, times(1)).blindImp();
-    verifyNoMoreInteractions(excalibur);
   }
 
+  /**
+   * Reset.
+   */
+  public void reset() {
+    processorJournal.reset();
+  }
+
+  /**
+   * Recover.
+   */
+  public void recover() {
+    DomainEvent domainEvent;
+    while (true) {
+      domainEvent = processorJournal.readNext();
+      if (domainEvent == null) {
+        break;
+      } else {
+        domainEvent.process();
+      }
+    }
+  }
 }

event-sourcing/src/main/java/com/iluwatar/event/sourcing/processor/JsonFileJournal.java

@@ -0,0 +1,144 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.event.sourcing.processor;
+
+import com.google.gson.Gson;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonParser;
+import com.iluwatar.event.sourcing.event.AccountCreateEvent;
+import com.iluwatar.event.sourcing.event.DomainEvent;
+import com.iluwatar.event.sourcing.event.MoneyDepositEvent;
+import com.iluwatar.event.sourcing.event.MoneyTransferEvent;
+import java.io.BufferedReader;
+import java.io.BufferedWriter;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.OutputStreamWriter;
+import java.io.Writer;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * This is the implementation of event journal.
+ * This implementation serialize/deserialize the events with JSON
+ * and writes/reads them on a Journal.json file at the working directory.
+ *
+ * Created by Serdar Hamzaogullari on 06.08.2017.
+ */
+public class JsonFileJournal {
+
+  private final File aFile;
+  private final List<String> events = new ArrayList<>();
+  private int index = 0;
+
+  /**
+   * Instantiates a new Json file journal.
+   */
+  public JsonFileJournal() {
+    aFile = new File("Journal.json");
+    if (aFile.exists()) {
+      try (BufferedReader input = new BufferedReader(
+          new InputStreamReader(new FileInputStream(aFile), "UTF-8"))) {
+        String line;
+        while ((line = input.readLine()) != null) {
+          events.add(line);
+        }
+      } catch (IOException e) {
+        throw new RuntimeException(e);
+      }
+    } else {
+      reset();
+    }
+  }
+
+
+  /**
+   * Write.
+   *
+   * @param domainEvent the domain event
+   */
+  public void write(DomainEvent domainEvent) {
+    Gson gson = new Gson();
+    JsonElement jsonElement;
+    if (domainEvent instanceof AccountCreateEvent) {
+      jsonElement = gson.toJsonTree(domainEvent, AccountCreateEvent.class);
+    } else if (domainEvent instanceof MoneyDepositEvent) {
+      jsonElement = gson.toJsonTree(domainEvent, MoneyDepositEvent.class);
+    }  else if (domainEvent instanceof MoneyTransferEvent) {
+      jsonElement = gson.toJsonTree(domainEvent, MoneyTransferEvent.class);
+    } else {
+      throw new RuntimeException("Journal Event not recegnized");
+    }
+
+    try (Writer output = new BufferedWriter(
+        new OutputStreamWriter(new FileOutputStream(aFile, true), "UTF-8"))) {
+      String eventString = jsonElement.toString();
+      output.write(eventString + "\r\n");
+    } catch (IOException e) {
+      throw new RuntimeException(e);
+    }
+  }
+
+
+  /**
+   * Reset.
+   */
+  public void reset() {
+    aFile.delete();
+  }
+
+
+  /**
+   * Read next domain event.
+   *
+   * @return the domain event
+   */
+  public DomainEvent readNext() {
+    if (index >= events.size()) {
+      return null;
+    }
+    String event = events.get(index);
+    index++;
+
+    JsonParser parser = new JsonParser();
+    JsonElement jsonElement = parser.parse(event);
+    String eventClassName = jsonElement.getAsJsonObject().get("eventClassName").getAsString();
+    Gson gson = new Gson();
+    DomainEvent domainEvent;
+    if (eventClassName.equals("AccountCreateEvent")) {
+      domainEvent = gson.fromJson(jsonElement, AccountCreateEvent.class);
+    } else if (eventClassName.equals("MoneyDepositEvent")) {
+      domainEvent = gson.fromJson(jsonElement, MoneyDepositEvent.class);
+    } else if (eventClassName.equals("MoneyTransferEvent")) {
+      domainEvent = gson.fromJson(jsonElement, MoneyTransferEvent.class);
+    }  else {
+      throw new RuntimeException("Journal Event not recegnized");
+    }
+
+    domainEvent.setRealTime(false);
+    return domainEvent;
+  }
+}

event-sourcing/src/main/java/com/iluwatar/event/sourcing/state/AccountAggregate.java

@@ -1,6 +1,6 @@
 /**
  * The MIT License
- * Copyright (c) 2014-2016 Ilkka Seppälä
+ * Copyright (c) 2014 Ilkka Seppälä
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -20,37 +20,52 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
-package com.iluwatar.bridge;
+package com.iluwatar.event.sourcing.state;
 
-import org.slf4j.Logger;
+import com.iluwatar.event.sourcing.domain.Account;
-import org.slf4j.LoggerFactory;
+import java.util.HashMap;
+import java.util.Map;
 
 /**
+ * This is the static accounts map holder class.
+ * This class holds the state of the accounts.
  *
- * Mjollnir
+ * Created by Serdar Hamzaogullari on 06.08.2017.
- *
  */
-public class Mjollnir extends FlyingMagicWeaponImpl {
+public class AccountAggregate {
 
-  private static final Logger LOGGER = LoggerFactory.getLogger(Mjollnir.class);
+  private static Map<Integer, Account> accounts = new HashMap<>();
 
-  @Override
+  private AccountAggregate() {
-  public void wieldImp() {
-    LOGGER.info("wielding Mjollnir");
   }
 
-  @Override
+  /**
-  public void swingImp() {
+   * Put account.
-    LOGGER.info("swinging Mjollnir");
+   *
+   * @param account the account
+   */
+  public static void putAccount(Account account) {
+    accounts.put(account.getAccountNo(), account);
   }
 
-  @Override
+  /**
-  public void unwieldImp() {
+   * Gets account.
-    LOGGER.info("unwielding Mjollnir");
+   *
+   * @param accountNo the account no
+   * @return the copy of the account or null if not found
+   */
+  public static Account getAccount(int accountNo) {
+    Account account = accounts.get(accountNo);
+    if (account == null) {
+      return null;
+    }
+    return account.copy();
   }
 
-  @Override
+  /**
-  public void flyImp() {
+   * Reset state.
-    LOGGER.info("Mjollnir hits the enemy in the air and returns back to the owner's hand");
+   */
+  public static void resetState() {
+    accounts = new HashMap<>();
   }
 }

event-sourcing/src/test/java/IntegrationTest.java

@@ -0,0 +1,99 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+import static com.iluwatar.event.sourcing.app.App.ACCOUNT_OF_DAENERYS;
+import static com.iluwatar.event.sourcing.app.App.ACCOUNT_OF_JON;
+
+import com.iluwatar.event.sourcing.domain.Account;
+import com.iluwatar.event.sourcing.event.AccountCreateEvent;
+import com.iluwatar.event.sourcing.event.MoneyDepositEvent;
+import com.iluwatar.event.sourcing.event.MoneyTransferEvent;
+import com.iluwatar.event.sourcing.processor.DomainEventProcessor;
+import com.iluwatar.event.sourcing.state.AccountAggregate;
+import java.math.BigDecimal;
+import java.util.Date;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+/**
+ * Intergartion Test for Event Sourcing state recovery
+ *
+ * Created by Serdar Hamzaogullari on 19.08.2017.
+ */
+public class IntegrationTest {
+
+  /**
+   * The Domain event processor.
+   */
+  private DomainEventProcessor eventProcessor;
+
+  /**
+   * Initialize.
+   */
+  @Before
+  public void initialize() {
+    eventProcessor = new DomainEventProcessor();
+  }
+
+  /**
+   * Test state recovery.
+   */
+  @Test
+  public void testStateRecovery() {
+    eventProcessor.reset();
+
+    eventProcessor.process(new AccountCreateEvent(
+        0, new Date().getTime(), ACCOUNT_OF_DAENERYS, "Daenerys Targaryen"));
+
+    eventProcessor.process(new AccountCreateEvent(
+        1, new Date().getTime(), ACCOUNT_OF_JON, "Jon Snow"));
+
+    eventProcessor.process(new MoneyDepositEvent(
+        2, new Date().getTime(), ACCOUNT_OF_DAENERYS,  new BigDecimal("100000")));
+
+    eventProcessor.process(new MoneyDepositEvent(
+        3, new Date().getTime(), ACCOUNT_OF_JON,  new BigDecimal("100")));
+
+    eventProcessor.process(new MoneyTransferEvent(
+        4, new Date().getTime(), new BigDecimal("10000"), ACCOUNT_OF_DAENERYS,
+        ACCOUNT_OF_JON));
+
+    Account accountOfDaenerysBeforeShotDown = AccountAggregate.getAccount(ACCOUNT_OF_DAENERYS);
+    Account accountOfJonBeforeShotDown = AccountAggregate.getAccount(ACCOUNT_OF_JON);
+
+    AccountAggregate.resetState();
+
+    eventProcessor = new DomainEventProcessor();
+    eventProcessor.recover();
+
+    Account accountOfDaenerysAfterShotDown = AccountAggregate.getAccount(ACCOUNT_OF_DAENERYS);
+    Account accountOfJonAfterShotDown = AccountAggregate.getAccount(ACCOUNT_OF_JON);
+
+    Assert.assertEquals(accountOfDaenerysBeforeShotDown.getMoney(),
+        accountOfDaenerysAfterShotDown.getMoney());
+    Assert
+        .assertEquals(accountOfJonBeforeShotDown.getMoney(), accountOfJonAfterShotDown.getMoney());
+  }
+
+}

factory-method/README.md

@@ -19,7 +19,49 @@ Define an interface for creating an object, but let subclasses
 decide which class to instantiate. Factory Method lets a class defer
 instantiation to subclasses.
 
-![alt text](./etc/factory-method_1.png "Factory Method")
+## Explanation
+Real world example
+
+> Blacksmith manufactures weapons. Elves require Elvish weapons and orcs require Orcish weapons. Depending on the customer at hand the right type of blacksmith is summoned.
+
+In plain words
+
+> It provides a way to delegate the instantiation logic to child classes.
+
+Wikipedia says
+
+> In class-based programming, the factory method pattern is a creational pattern that uses factory methods to deal with the problem of creating objects without having to specify the exact class of the object that will be created. This is done by creating objects by calling a factory method—either specified in an interface and implemented by child classes, or implemented in a base class and optionally overridden by derived classes—rather than by calling a constructor.
+
+ **Programmatic Example**
+
+Taking our blacksmith example above. First of all we have a blacksmith interface and some implementations for it
+
+```
+public interface Blacksmith {
+  Weapon manufactureWeapon(WeaponType weaponType);
+}
+
+public class ElfBlacksmith implements Blacksmith {
+  public Weapon manufactureWeapon(WeaponType weaponType) {
+    return new ElfWeapon(weaponType);
+  }
+}
+
+public class OrcBlacksmith implements Blacksmith {
+  public Weapon manufactureWeapon(WeaponType weaponType) {
+    return new OrcWeapon(weaponType);
+  }
+}
+```
+
+Now as the customers come the correct type of blacksmith is summoned and requested weapons are manufactured
+
+```
+Blacksmith blacksmith = new ElfBlacksmith();
+blacksmith.manufactureWeapon(WeaponType.SPEAR);
+blacksmith.manufactureWeapon(WeaponType.AXE);
+// Elvish weapons are created
+```
 
 ## Applicability
 Use the Factory Method pattern when

factory-method/etc/factory-method.urm.puml

@@ -1,54 +0,0 @@
-@startuml
-package com.iluwatar.factory.method {
-  class App {
-    - LOGGER : Logger {static}
-    - blacksmith : Blacksmith
-    + App(blacksmith : Blacksmith)
-    + main(args : String[]) {static}
-    - manufactureWeapons()
-  }
-  interface Blacksmith {
-    + manufactureWeapon(WeaponType) : Weapon {abstract}
-  }
-  class ElfBlacksmith {
-    + ElfBlacksmith()
-    + manufactureWeapon(weaponType : WeaponType) : Weapon
-  }
-  class ElfWeapon {
-    - weaponType : WeaponType
-    + ElfWeapon(weaponType : WeaponType)
-    + getWeaponType() : WeaponType
-    + toString() : String
-  }
-  class OrcBlacksmith {
-    + OrcBlacksmith()
-    + manufactureWeapon(weaponType : WeaponType) : Weapon
-  }
-  class OrcWeapon {
-    - weaponType : WeaponType
-    + OrcWeapon(weaponType : WeaponType)
-    + getWeaponType() : WeaponType
-    + toString() : String
-  }
-  interface Weapon {
-    + getWeaponType() : WeaponType {abstract}
-  }
-  enum WeaponType {
-    + AXE {static}
-    + SHORT_SWORD {static}
-    + SPEAR {static}
-    + UNDEFINED {static}
-    - title : String
-    + toString() : String
-    + valueOf(name : String) : WeaponType {static}
-    + values() : WeaponType[] {static}
-  }
-}
-ElfWeapon -->  "-weaponType" WeaponType
-OrcWeapon -->  "-weaponType" WeaponType
-App -->  "-blacksmith" Blacksmith
-ElfBlacksmith ..|> Blacksmith 
-ElfWeapon ..|> Weapon 
-OrcBlacksmith ..|> Blacksmith 
-OrcWeapon ..|> Weapon 
-@enduml

feature-toggle/README.md

@@ -22,7 +22,7 @@ going to phase out is never removed, causing redundant code smells and increased
 ![alt text](./etc/feature-toggle.png "Feature Toggle")
 
 ## Applicability
-Use the Feature Toogle pattern when
+Use the Feature Toggle pattern when
 
 * Giving different features to different users.
 * Rolling out a new feature incrementally.

layers/README.md

@@ -21,7 +21,7 @@ Layers is an architectural style where software responsibilities are
 ## Applicability
 Use the Layers architecture when
 
-* you want clearly divide software responsibilities into differents parts of the program
+* you want clearly divide software responsibilities into different parts of the program
 * you want to prevent a change from propagating throughout the application
 * you want to make your application more maintainable and testable
 

model-view-presenter/src/main/java/com/iluwatar/model/view/presenter/FileLoader.java

@@ -25,6 +25,10 @@ package com.iluwatar.model.view.presenter;
 import java.io.BufferedReader;
 import java.io.File;
 import java.io.FileReader;
+import java.io.Serializable;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
  * Every instance of this class represents the Model component in the Model-View-Presenter
@@ -32,7 +36,14 @@ import java.io.FileReader;
  * <p>
  * It is responsible for reading and loading the contents of a given file.
  */
-public class FileLoader {
+public class FileLoader implements Serializable{
+
+  /**
+   * Generated serial version UID
+   */
+  private static final long serialVersionUID = -4745803872902019069L;
+  
+  private static final Logger LOGGER = LoggerFactory.getLogger(FileLoader.class);
 
   /**
    * Indicates if the file is loaded or not.
@@ -48,7 +59,8 @@ public class FileLoader {
    * Loads the data of the file specified.
    */
   public String loadData() {
-    try (BufferedReader br = new BufferedReader(new FileReader(new File(this.fileName)))) {
+    String dataFileName = this.fileName;
+    try (BufferedReader br = new BufferedReader(new FileReader(new File(dataFileName)))) {
       StringBuilder sb = new StringBuilder();
       String line;
 
@@ -60,7 +72,7 @@ public class FileLoader {
 
       return sb.toString();
     } catch (Exception e) {
-      e.printStackTrace();
+      LOGGER.error("File {} does not exist", dataFileName);
     }
 
     return null;

model-view-presenter/src/main/java/com/iluwatar/model/view/presenter/FileSelectorPresenter.java

@@ -22,13 +22,20 @@
  */
 package com.iluwatar.model.view.presenter;
 
+import java.io.Serializable;
+
 /**
  * Every instance of this class represents the Presenter component in the Model-View-Presenter
  * architectural pattern.
  * <p>
  * It is responsible for reacting to the user's actions and update the View component.
  */
-public class FileSelectorPresenter {
+public class FileSelectorPresenter implements Serializable{
+
+  /**
+   * Generated serial version UID
+   */
+  private static final long serialVersionUID = 1210314339075855074L;
 
   /**
    * The View component that the presenter interacts with.

model-view-presenter/src/main/java/com/iluwatar/model/view/presenter/FileSelectorView.java

@@ -22,11 +22,13 @@
  */
 package com.iluwatar.model.view.presenter;
 
+import java.io.Serializable;
+
 /**
  * This interface represents the View component in the Model-View-Presenter pattern. It can be
  * implemented by either the GUI components, or by the Stub.
  */
-public interface FileSelectorView {
+public interface FileSelectorView extends Serializable{
 
   /**
    * Opens the view.

object-pool/src/main/java/com/iluwatar/object/pool/ObjectPool.java

@@ -55,7 +55,7 @@ public abstract class ObjectPool<T> {
   }
 
   @Override
-  public String toString() {
+  public synchronized String toString() {
     return String.format("Pool available=%d inUse=%d", available.size(), inUse.size());
   }
 }

pom.xml

@@ -143,7 +143,8 @@
         <module>extension-objects</module>
         <module>marker</module>
         <module>cqrs</module>
-
+        <module>event-sourcing</module>
+        <module>data-transfer-object</module>
     </modules>
 
     <dependencyManagement>
@@ -460,6 +461,15 @@
                     <skipForProjects>
                         <!-- skip for parent project -->
                         <param>java-design-patterns</param>
+                        <param>singleton</param>
+                        <param>factory-method</param>
+                        <param>abstract-factory</param>
+                        <param>builder</param>
+                        <param>prototype</param>
+                        <param>adapter</param>
+                        <param>bridge</param>
+                        <param>composite</param>
+                        <param>decorator</param>
                     </skipForProjects>
                 </configuration>
             </plugin>

promise/README.md

@@ -27,7 +27,7 @@ in a synchronous way.
 Promise pattern is applicable in concurrent programming when some work needs to be done asynchronously
 and:
 
-* code maintainablity and readability suffers due to callback hell.
+* code maintainability and readability suffers due to callback hell.
 * you need to compose promises and need better error handling for asynchronous tasks.
 * you want to use functional style of programming.
 
@@ -44,4 +44,4 @@ and:
 ## Credits
 
 * [You are missing the point to Promises](https://gist.github.com/domenic/3889970)
-* [Functional style callbacks using CompleteableFuture](https://www.infoq.com/articles/Functional-Style-Callbacks-Using-CompletableFuture)
+* [Functional style callbacks using CompletableFuture](https://www.infoq.com/articles/Functional-Style-Callbacks-Using-CompletableFuture)

prototype/README.md

@@ -15,14 +15,57 @@ tags:
 Specify the kinds of objects to create using a prototypical
 instance, and create new objects by copying this prototype.
 
-![alt text](./etc/prototype_1.png "Prototype")
+## Explanation
+Real world example
+
+> Remember Dolly? The sheep that was cloned! Lets not get into the details but the key point here is that it is all about cloning.
+
+In plain words
+
+> Create object based on an existing object through cloning.
+
+Wikipedia says
+
+> The prototype pattern is a creational design pattern in software development. It is used when the type of objects to create is determined by a prototypical instance, which is cloned to produce new objects.
+
+In short, it allows you to create a copy of an existing object and modify it to your needs, instead of going through the trouble of creating an object from scratch and setting it up.
+
+**Programmatic Example**
+
+In Java, it can be easily done by implementing `Cloneable` and overriding `clone` from `Object`
+
+```
+class Sheep implements Cloneable {
+  private String name;
+  public Sheep(String name) { this.name = name; }
+  public void setName(String name) { this.name = name; }
+  public String getName() { return name; }
+  @Override
+  public Sheep clone() throws CloneNotSupportedException {
+    return new Sheep(name);
+  }
+}
+```
+
+Then it can be cloned like below
+
+```
+Sheep original = new Sheep("Jolly");
+System.out.println(original.getName()); // Jolly
+
+// Clone and modify what is required
+Sheep cloned = original.clone();
+cloned.setName("Dolly");
+System.out.println(cloned.getName()); // Dolly
+```
 
 ## Applicability
 Use the Prototype pattern when a system should be independent of how its products are created, composed and represented; and
 
-* when the classes to instantiate are specified at run-time, for example, by dynamic loading; or
+* when the classes to instantiate are specified at run-time, for example, by dynamic loading
-* to avoid building a class hierarchy of factories that parallels the class hierarchy of products; or
+* to avoid building a class hierarchy of factories that parallels the class hierarchy of products
 * when instances of a class can have one of only a few different combinations of state. It may be more convenient to install a corresponding number of prototypes and clone them rather than instantiating the class manually, each time with the appropriate state
+* when object creation is expensive compared to cloning
 
 ## Real world examples