Merge remote-tracking branch 'upstream/master' into data-bus

* upstream/master: (67 commits)
  Set version for next development iteration
  Reached milestone 1.15.0
  #539 Checkstyle fix
  #539 More Checkstyle fixes
  #539 Checkstyle fixes
  #497 Add missing puml and license headers
  #77 Add missing license header
  Work on #190: urm/puml updates * added pumlid where it was missing and possible * removed pumlid where it generated a bad image * regenerated some incorrect puml's * added 'left to right direction' puml prefix to some diagrams to improve the automatic layouting
  Removed AvoidStarImport Rule Added JavaDocType Rule
  Update App.java
  Update App.java
  Update after changes from review. Additional improvements.
  Pom.xml files fixed.
  #66 Balking Pattern
  fixed pmd violation
  fixed checkstyle violations
  diagrams added
  comments, tests and description
  changed parent POM version #69
  apply changes from review #69
  ...

# Conflicts:
#	pom.xml

abstract-document/pom.xml

@@ -29,7 +29,7 @@
     <parent>
         <artifactId>java-design-patterns</artifactId>
         <groupId>com.iluwatar</groupId>
-        <version>1.15.0-SNAPSHOT</version>
+        <version>1.16.0-SNAPSHOT</version>
     </parent>
     <artifactId>abstract-document</artifactId>
     <dependencies>

abstract-factory/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.15.0-SNAPSHOT</version>
+    <version>1.16.0-SNAPSHOT</version>
   </parent>
   <artifactId>abstract-factory</artifactId>
   <dependencies>

abstract-factory/src/test/java/com/iluwatar/abstractfactory/AbstractFactoryTest.java

@@ -28,6 +28,9 @@ import static org.junit.Assert.assertTrue;
 import org.junit.Before;
 import org.junit.Test;
 
+/**
+ * Test for abstract factory
+ */
 public class AbstractFactoryTest {
 
   private App app = new App();

adapter/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.15.0-SNAPSHOT</version>
+    <version>1.16.0-SNAPSHOT</version>
   </parent>
   <artifactId>adapter</artifactId>
   <dependencies>

aggregator-microservices/aggregator-service/pom.xml

@@ -29,7 +29,7 @@
     <parent>
         <artifactId>aggregator-microservices</artifactId>
         <groupId>com.iluwatar</groupId>
-        <version>1.15.0-SNAPSHOT</version>
+        <version>1.16.0-SNAPSHOT</version>
     </parent>
     <modelVersion>4.0.0</modelVersion>
 

aggregator-microservices/aggregator-service/src/main/java/com/iluwatar/aggregator/microservices/App.java

@@ -25,6 +25,9 @@ package com.iluwatar.aggregator.microservices;
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
 
+/**
+ * Spring Boot EntryPoint Class
+ */
 @SpringBootApplication
 public class App {
 

aggregator-microservices/aggregator-service/src/test/java/com/iluwatar/aggregator/microservices/AggregatorTest.java

@@ -22,15 +22,18 @@
  */
 package com.iluwatar.aggregator.microservices;
 
+import static org.junit.Assert.assertEquals;
+import static org.mockito.Mockito.when;
+
 import org.junit.Before;
 import org.junit.Test;
 import org.mockito.InjectMocks;
 import org.mockito.Mock;
 import org.mockito.MockitoAnnotations;
 
-import static org.junit.Assert.assertEquals;
+/**
-import static org.mockito.Mockito.when;
+ * Test Aggregation of domain objects
-
+ */
 public class AggregatorTest {
 
   @InjectMocks
@@ -64,4 +67,4 @@ public class AggregatorTest {
     assertEquals(inventories, testProduct.getProductInventories());
   }
 
-}
+}

aggregator-microservices/information-microservice/pom.xml

@@ -29,7 +29,7 @@
     <parent>
         <artifactId>aggregator-microservices</artifactId>
         <groupId>com.iluwatar</groupId>
-        <version>1.15.0-SNAPSHOT</version>
+        <version>1.16.0-SNAPSHOT</version>
     </parent>
     <modelVersion>4.0.0</modelVersion>
 

aggregator-microservices/information-microservice/src/main/java/com/iluwatar/information/microservice/InformationController.java

@@ -26,6 +26,9 @@ import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RequestMethod;
 import org.springframework.web.bind.annotation.RestController;
 
+/**
+ * Controller providing endpoints to retrieve information about products
+ */
 @RestController
 public class InformationController {
 

aggregator-microservices/information-microservice/src/test/java/com/iluwatar/information/microservice/InformationControllerTest.java

@@ -25,6 +25,9 @@ package com.iluwatar.information.microservice;
 import org.junit.Assert;
 import org.junit.Test;
 
+/**
+ * Test for Information Rest Controller
+ */
 public class InformationControllerTest {
 
   @Test
@@ -36,4 +39,4 @@ public class InformationControllerTest {
     Assert.assertEquals("The Product Title.", title);
   }
 
-}
+}

aggregator-microservices/inventory-microservice/pom.xml

@@ -29,7 +29,7 @@
     <parent>
         <artifactId>aggregator-microservices</artifactId>
         <groupId>com.iluwatar</groupId>
-        <version>1.15.0-SNAPSHOT</version>
+        <version>1.16.0-SNAPSHOT</version>
     </parent>
     <modelVersion>4.0.0</modelVersion>
 

aggregator-microservices/inventory-microservice/src/main/java/com/iluwatar/inventory/microservice/InventoryController.java

@@ -26,6 +26,9 @@ import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RequestMethod;
 import org.springframework.web.bind.annotation.RestController;
 
+/**
+ * Controller providing endpoints to retrieve product inventories
+ */
 @RestController
 public class InventoryController {
 

aggregator-microservices/inventory-microservice/src/test/java/com/iluwatar/inventory/microservice/InventoryControllerTest.java

@@ -25,8 +25,10 @@ package com.iluwatar.inventory.microservice;
 import org.junit.Assert;
 import org.junit.Test;
 
+/**
+ * Test Inventory Rest Controller
+ */
 public class InventoryControllerTest {
-
   @Test
   public void testGetProductInventories() throws Exception {
     InventoryController inventoryController = new InventoryController();
@@ -35,4 +37,4 @@ public class InventoryControllerTest {
 
     Assert.assertEquals(5, numberOfInventories);
   }
-}
+}

aggregator-microservices/pom.xml

@@ -29,7 +29,7 @@
     <parent>
         <artifactId>java-design-patterns</artifactId>
         <groupId>com.iluwatar</groupId>
-        <version>1.15.0-SNAPSHOT</version>
+        <version>1.16.0-SNAPSHOT</version>
     </parent>
     <modelVersion>4.0.0</modelVersion>
     <artifactId>aggregator-microservices</artifactId>

api-gateway/api-gateway-service/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <artifactId>api-gateway</artifactId>
     <groupId>com.iluwatar</groupId>
-    <version>1.15.0-SNAPSHOT</version>
+    <version>1.16.0-SNAPSHOT</version>
   </parent>
   <modelVersion>4.0.0</modelVersion>
   <artifactId>api-gateway-service</artifactId>

api-gateway/api-gateway-service/src/main/java/com/iluwatar/api/gateway/ImageClientImpl.java

@@ -35,7 +35,7 @@ import java.io.IOException;
  * An adapter to communicate with the Image microservice
  */
 @Component
-public class ImageClientImpl implements ImageClient{
+public class ImageClientImpl implements ImageClient {
   /**
    * Makes a simple HTTP Get request to the Image microservice
    * @return The path to the image

api-gateway/api-gateway-service/src/main/java/com/iluwatar/api/gateway/PriceClientImpl.java

@@ -35,7 +35,7 @@ import java.io.IOException;
  * An adapter to communicate with the Price microservice
  */
 @Component
-public class PriceClientImpl implements PriceClient{
+public class PriceClientImpl implements PriceClient {
   /**
    * Makes a simple HTTP Get request to the Price microservice
    * @return The price of the product

api-gateway/api-gateway-service/src/test/java/com/iluwatar/api/gateway/ApiGatewayTest.java

@@ -22,15 +22,18 @@
  */
 package com.iluwatar.api.gateway;
 
+import static org.junit.Assert.assertEquals;
+import static org.mockito.Mockito.when;
+
 import org.junit.Before;
 import org.junit.Test;
 import org.mockito.InjectMocks;
 import org.mockito.Mock;
 import org.mockito.MockitoAnnotations;
 
-import static org.junit.Assert.assertEquals;
+/**
-import static org.mockito.Mockito.when;
+ * Test API Gateway Pattern
-
+ */
 public class ApiGatewayTest {
 
   @InjectMocks

api-gateway/image-microservice/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <artifactId>api-gateway</artifactId>
     <groupId>com.iluwatar</groupId>
-    <version>1.15.0-SNAPSHOT</version>
+    <version>1.16.0-SNAPSHOT</version>
   </parent>
 
   <modelVersion>4.0.0</modelVersion>

api-gateway/image-microservice/src/test/java/com/iluwatar/image/microservice/ImageControllerTest.java

@@ -25,6 +25,9 @@ package com.iluwatar.image.microservice;
 import org.junit.Assert;
 import org.junit.Test;
 
+/**
+ * Test for Image Rest Controller
+ */
 public class ImageControllerTest {
   @Test
   public void testGetImagePath() {

api-gateway/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <artifactId>java-design-patterns</artifactId>
     <groupId>com.iluwatar</groupId>
-    <version>1.15.0-SNAPSHOT</version>
+    <version>1.16.0-SNAPSHOT</version>
   </parent>
   <modelVersion>4.0.0</modelVersion>
   <artifactId>api-gateway</artifactId>

api-gateway/price-microservice/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <artifactId>api-gateway</artifactId>
     <groupId>com.iluwatar</groupId>
-    <version>1.15.0-SNAPSHOT</version>
+    <version>1.16.0-SNAPSHOT</version>
   </parent>
 
   <modelVersion>4.0.0</modelVersion>

api-gateway/price-microservice/src/test/java/com/iluwatar/price/microservice/PriceControllerTest.java

@@ -25,6 +25,10 @@ package com.iluwatar.price.microservice;
 import org.junit.Assert;
 import org.junit.Test;
 
+
+/**
+ * Test for Price Rest Controller
+ */
 public class PriceControllerTest {
   @Test
   public void testgetPrice() {

async-method-invocation/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.15.0-SNAPSHOT</version>
+    <version>1.16.0-SNAPSHOT</version>
   </parent>
   <artifactId>async-method-invocation</artifactId>
   <dependencies>

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

@@ -25,8 +25,8 @@ package com.iluwatar.async.method.invocation;
 import java.util.concurrent.ExecutionException;
 
 /**
- * 
  * AsyncResult interface
+ * @param <T> parameter returned when getValue is invoked
  */
 public interface AsyncResult<T> {
 

balking/README.md

@@ -0,0 +1,27 @@
+---
+layout: pattern
+title: Balking
+folder: balking
+permalink: /patterns/balking/
+categories: Concurrency
+tags:
+ - Java
+ - Difficulty-Beginner
+---
+
+## Intent
+Balking Pattern is used to prevent an object from executing certain code if it is an
+incomplete or inappropriate state
+
+![alt text](./etc/balking.png "Balking")
+
+## Applicability
+Use the Balking pattern when
+
+*you want to invoke an action on an object only when it is in a particular state
+*objects are generally only in a state that is prone to balking temporarily
+but for an unknown amount of time
+
+## Related patterns
+* Guarded Suspendion Pattern
+* Double Checked Locking Pattern

balking/etc/balking.ucls

@@ -0,0 +1,46 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<class-diagram version="1.1.13" 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.balking.App" project="balking" 
+    file="/balking/src/main/java/com/iluwatar/balking/App.java" binary="false" corner="BOTTOM_RIGHT">    
+    <position height="113" width="114" x="135" y="103"/>    
+    <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.balking.WashingMachine" project="balking" 
+    file="/balking/src/main/java/com/iluwatar/balking/WashingMachine.java" binary="false" corner="BOTTOM_RIGHT">    
+    <position height="149" width="268" x="289" y="103"/>    
+    <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="3" language="java" name="com.iluwatar.balking.WashingMachineState" project="balking" 
+    file="/balking/src/main/java/com/iluwatar/balking/WashingMachineState.java" binary="false" corner="BOTTOM_RIGHT">    
+    <position height="113" width="192" x="289" y="292"/>    
+    <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>  
+  <association id="4">    
+    <end type="SOURCE" refId="2" navigable="false">      
+      <attribute id="5" name="washingMachineState"/>      
+      <multiplicity id="6" minimum="0" maximum="1"/>    
+    </end>    
+    <end type="TARGET" refId="3" 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>

balking/etc/balking.urm.puml

@@ -0,0 +1,24 @@
+@startuml
+package com.iluwatar.balking {
+  class App {
+    - LOGGER : Logger {static}
+    + App()
+    + main(args : String[]) {static}
+  }
+  class WashingMachine {
+    - LOGGER : Logger {static}
+    - washingMachineState : WashingMachineState
+    + WashingMachine()
+    + endOfWashing()
+    + getWashingMachineState() : WashingMachineState
+    + wash()
+  }
+  enum WashingMachineState {
+    + ENABLED {static}
+    + WASHING {static}
+    + valueOf(name : String) : WashingMachineState {static}
+    + values() : WashingMachineState[] {static}
+  }
+}
+WashingMachine -->  "-washingMachineState" WashingMachineState
+@enduml

balking/pom.xml

@@ -0,0 +1,46 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+
+    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.
+
+-->
+<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">
+  <parent>
+    <artifactId>java-design-patterns</artifactId>
+    <groupId>com.iluwatar</groupId>
+    <version>1.16.0-SNAPSHOT</version>
+  </parent>
+  <modelVersion>4.0.0</modelVersion>
+
+  <artifactId>balking</artifactId>
+  <dependencies>
+    <dependency>
+      <groupId>junit</groupId>
+      <artifactId>junit</artifactId>
+      <scope>test</scope>
+    </dependency>
+  </dependencies>
+
+
+</project>

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

@@ -0,0 +1,65 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 Ilkka Seppälä
+ * <p>
+ * 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:
+ * <p>
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * <p>
+ * 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.balking;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * In Balking Design Pattern if an object’s method is invoked when it is in an inappropriate state,
+ * then the method will return without doing anything. Objects that use this pattern are generally only in a
+ * state that is prone to balking temporarily but for an unknown amount of time
+ *
+ * In this example implementation WashingMachine is an object that has two states
+ * in which it can be: ENABLED and WASHING. If the machine is ENABLED
+ * the state is changed into WASHING that any other thread can't invoke this action on this and then do the job.
+ * On the other hand if it have been already washing and any other thread execute wash()
+ * it can't do that once again and returns doing nothing.
+ */
+
+public class App {
+
+  private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
+
+  /**
+   * @param args the command line arguments - not used
+   */
+  public static void main(String... args) {
+    final WashingMachine washingMachine = new WashingMachine();
+    ExecutorService executorService = Executors.newFixedThreadPool(3);
+    for (int i = 0; i < 3; i++) {
+      executorService.execute(washingMachine::wash);
+    }
+    executorService.shutdown();
+    try {
+      executorService.awaitTermination(10, TimeUnit.SECONDS);
+    } catch (InterruptedException ie) {
+      LOGGER.error("ERROR: Waiting on executor service shutdown!");
+    }
+  }
+
+}

balking/src/main/java/com/iluwatar/balking/WashingMachine.java

@@ -0,0 +1,76 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 Ilkka Seppälä
+ * <p>
+ * 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:
+ * <p>
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * <p>
+ * 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.balking;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Washing machine class
+ */
+public class WashingMachine {
+
+  private static final Logger LOGGER = LoggerFactory.getLogger(WashingMachine.class);
+
+  private WashingMachineState washingMachineState;
+
+  public WashingMachine() {
+    washingMachineState = WashingMachineState.ENABLED;
+  }
+
+  public WashingMachineState getWashingMachineState() {
+    return washingMachineState;
+  }
+
+  /**
+   * Method responsible for washing
+   * if the object is in appropriate state
+   */
+  public void wash() {
+    synchronized (this) {
+      LOGGER.info("{}: Actual machine state: {}", Thread.currentThread().getName(), getWashingMachineState());
+      if (washingMachineState == WashingMachineState.WASHING) {
+        LOGGER.error("ERROR: Cannot wash if the machine has been already washing!");
+        return;
+      }
+      washingMachineState = WashingMachineState.WASHING;
+    }
+    LOGGER.info("{}: Doing the washing", Thread.currentThread().getName());
+    try {
+      Thread.sleep(50);
+    } catch (InterruptedException ie) {
+      ie.printStackTrace();
+    }
+    endOfWashing();
+  }
+
+  /**
+   * Method responsible of ending the washing
+   * by changing machine state
+   */
+  public synchronized void endOfWashing() {
+    washingMachineState = WashingMachineState.ENABLED;
+    LOGGER.info("{}: Washing completed.", Thread.currentThread().getId());
+  }
+
+}

balking/src/main/java/com/iluwatar/balking/WashingMachineState.java

@@ -0,0 +1,32 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 Ilkka Seppälä
+ * <p>
+ * 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:
+ * <p>
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * <p>
+ * 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.balking;
+
+/**
+ * WashingMachineState enum describes in which state machine is,
+ * it can be enabled and ready to work as well as during washing
+ */
+
+public enum WashingMachineState {
+  ENABLED, WASHING
+}

balking/src/test/java/com/iluwatar/balking/AppTest.java

@@ -0,0 +1,39 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 Ilkka Seppälä
+ * <p>
+ * 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:
+ * <p>
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * <p>
+ * 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.balking;
+
+import org.junit.Test;
+
+/**
+ * Application test
+ */
+public class AppTest {
+
+  @Test
+  public void main() throws Exception {
+    String[] args = {};
+    App.main(args);
+  }
+
+}

balking/src/test/java/com/iluwatar/balking/WashingMachineTest.java

@@ -0,0 +1,65 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 Ilkka Seppälä
+ * <p>
+ * 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:
+ * <p>
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * <p>
+ * 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.balking;
+
+import org.junit.Test;
+
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+
+import static org.junit.Assert.*;
+
+/**
+ * Tests for {@link WashingMachine}
+ */
+public class WashingMachineTest {
+
+  private volatile WashingMachineState machineStateGlobal;
+
+  @Test
+  public void wash() throws Exception {
+    WashingMachine washingMachine = new WashingMachine();
+    ExecutorService executorService = Executors.newFixedThreadPool(2);
+    executorService.execute(washingMachine::wash);
+    executorService.execute(() -> {
+      washingMachine.wash();
+      machineStateGlobal = washingMachine.getWashingMachineState();
+    });
+    executorService.shutdown();
+    try {
+      executorService.awaitTermination(10, TimeUnit.SECONDS);
+    } catch (InterruptedException ie) {
+      ie.printStackTrace();
+    }
+    assertEquals(WashingMachineState.WASHING, machineStateGlobal);
+  }
+
+  @Test
+  public void endOfWashing() throws Exception {
+    WashingMachine washingMachine = new WashingMachine();
+    washingMachine.wash();
+    assertEquals(WashingMachineState.ENABLED, washingMachine.getWashingMachineState());
+  }
+
+}

bridge/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.15.0-SNAPSHOT</version>
+    <version>1.16.0-SNAPSHOT</version>
   </parent>
   <artifactId>bridge</artifactId>
   <dependencies>

builder/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.15.0-SNAPSHOT</version>
+    <version>1.16.0-SNAPSHOT</version>
   </parent>
   <artifactId>builder</artifactId>
   <dependencies>

business-delegate/pom.xml

@@ -30,7 +30,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.15.0-SNAPSHOT</version>
+		<version>1.16.0-SNAPSHOT</version>
 	</parent>
 	<artifactId>business-delegate</artifactId>
 	<dependencies>

caching/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.15.0-SNAPSHOT</version>
+    <version>1.16.0-SNAPSHOT</version>
   </parent>
   <artifactId>caching</artifactId>
   <dependencies>

callback/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.15.0-SNAPSHOT</version>
+    <version>1.16.0-SNAPSHOT</version>
   </parent>
   <artifactId>callback</artifactId>
   <dependencies>

chain/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.15.0-SNAPSHOT</version>
+    <version>1.16.0-SNAPSHOT</version>
   </parent>
   <artifactId>chain</artifactId>
   <dependencies>

checkstyle.xml

@@ -32,10 +32,10 @@
     Source = https://github.com/checkstyle/checkstyle/tree/master/src/main/resources
 
     Checkstyle configurartion that checks the Google coding conventions from:
-    
+
     -  Google Java Style
        https://google-styleguide.googlecode.com/svn-history/r130/trunk/javaguide.html
-       
+
     Checkstyle is very configurable. Be sure to read the documentation at
     http://checkstyle.sf.net (or in your downloaded distribution).
 
@@ -44,12 +44,12 @@
     To completely disable a check, just comment it out or delete it from the file.
 
     Authors: Max Vetrenko, Ruslan Diachenko, Roman Ivanov.
-    
+
  -->
 
 <module name="Checker">
     <property name="charset" value="UTF-8"/>
-	
+
 	<property name="fileExtensions" value="java, xml, properties"/>
 
     <property name="severity" value="error"/>
@@ -77,7 +77,6 @@
             <property name="max" value="120"/>
             <property name="ignorePattern" value="^package.*|^import.*|a href|href|http://|https://|ftp://"/>
         </module>
-        <module name="AvoidStarImport"/>
         <module name="OneTopLevelClass"/>
         <module name="NoLineWrap"/>
         <module name="EmptyBlock">
@@ -120,7 +119,7 @@
             <property name="tokens" value="COMMA"/>
             <property name="option" value="EOL"/>
         </module>
-		
+
         <!-- Checks for Naming Conventions.                  -->
         <!-- See http://checkstyle.sf.net/config_naming.html -->
         <module name="ConstantName"/>
@@ -185,6 +184,10 @@
             <property name="allowedAnnotations" value="Override, Test, Before, After, Parameters, Given, When, BeforeClass, AfterClass, Parameterized"/>
             <property name="allowThrowsTagsForSubclasses" value="true"/>
         </module>
+        <module name="JavadocType">
+            <property name="scope" value="public"/>
+            <property name="allowUnknownTags" value="true"/>
+        </module>
         <module name="MethodName">
             <property name="format" value="^[a-z][a-z0-9][a-zA-Z0-9_]*$"/>
             <message key="name.invalidPattern"

command/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.15.0-SNAPSHOT</version>
+    <version>1.16.0-SNAPSHOT</version>
   </parent>
   <artifactId>command</artifactId>
   <dependencies>

composite/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.15.0-SNAPSHOT</version>
+    <version>1.16.0-SNAPSHOT</version>
   </parent>
   <artifactId>composite</artifactId>
   <dependencies>

converter/README.md

@@ -0,0 +1,29 @@
+---
+layout: pattern
+title: Converter
+folder: converter
+permalink: /patterns/converter/
+categories:
+tags:
+ - Java
+ - Difficulty-Beginner
+---
+
+## Intent
+The purpose of the Converter Pattern is to provide a generic, common way of bidirectional
+conversion between corresponding types, allowing a clean implementation in which the types do not
+need to be aware of each other. Moreover, the Converter Pattern introduces bidirectional collection
+mapping, reducing a boilerplate code to minimum.
+
+![alt text](./etc/converter.png "Converter Pattern")
+
+## Applicability
+Use the Converter Pattern in the following situations:
+
+* When you have types that logically correspond which other and you need to convert entities between them
+* When you want to provide different ways of types conversions depending on a context
+* Whenever you introduce a DTO (Data transfer object), you will probably need to convert it into the domain equivalence
+
+## Credits
+
+* [Converter](http://www.xsolve.pl/blog/converter-pattern-in-java-8/)

converter/etc/Converter.ucls

@@ -0,0 +1,51 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<class-diagram version="1.1.14" 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.converter.Converter" project="converter" 
+    file="/converter/src/main/java/com/iluwatar/converter/Converter.java" binary="false" corner="BOTTOM_RIGHT">    
+    <position height="189" width="226" x="41" y="37"/>    
+    <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.converter.UserConverter" project="converter" 
+    file="/converter/src/main/java/com/iluwatar/converter/UserConverter.java" binary="false" corner="BOTTOM_RIGHT">    
+    <position height="81" width="107" x="41" y="356"/>    
+    <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.converter.User" project="converter" 
+    file="/converter/src/main/java/com/iluwatar/converter/User.java" binary="false" corner="BOTTOM_RIGHT">    
+    <position height="279" width="188" x="307" y="37"/>    
+    <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.converter.UserDto" project="converter" 
+    file="/converter/src/main/java/com/iluwatar/converter/UserDto.java" binary="false" corner="BOTTOM_RIGHT">    
+    <position height="279" width="204" x="535" y="37"/>    
+    <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="5">    
+    <end type="SOURCE" refId="2"/>    
+    <end type="TARGET" refId="1"/>  
+  </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>

converter/etc/converter.urm.puml

@@ -0,0 +1,49 @@
+@startuml
+package com.iluwatar.converter {
+  class App {
+    + App()
+    + main(args : String[]) {static}
+  }
+  class Converter<T, U> {
+    - fromDto : Function<T, U>
+    - fromEntity : Function<U, T>
+    + Converter<T, U>(fromDto : Function<T, U>, fromEntity : Function<U, T>)
+    + convertFromDto(userDto : T) : U
+    + convertFromEntity(user : U) : T
+    + createFromDtos(dtoUsers : Collection<T>) : List<U>
+    + createFromEntities(users : Collection<U>) : List<T>
+  }
+  class User {
+    - firstName : String
+    - isActive : boolean
+    - lastName : String
+    - userId : String
+    + User(firstName : String, lastName : String, isActive : boolean, userId : String)
+    + equals(o : Object) : boolean
+    + getFirstName() : String
+    + getLastName() : String
+    + getUserId() : String
+    + hashCode() : int
+    + isActive() : boolean
+    + toString() : String
+  }
+  class UserConverter {
+    + UserConverter()
+  }
+  class UserDto {
+    - email : String
+    - firstName : String
+    - isActive : boolean
+    - lastName : String
+    + UserDto(firstName : String, lastName : String, isActive : boolean, email : String)
+    + equals(o : Object) : boolean
+    + getEmail() : String
+    + getFirstName() : String
+    + getLastName() : String
+    + hashCode() : int
+    + isActive() : boolean
+    + toString() : String
+  }
+}
+UserConverter --|> Converter 
+@enduml

converter/pom.xml

@@ -0,0 +1,49 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+
+    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.
+
+-->
+<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">
+    <parent>
+        <artifactId>java-design-patterns</artifactId>
+        <groupId>com.iluwatar</groupId>
+        <version>1.16.0-SNAPSHOT</version>
+    </parent>
+    <modelVersion>4.0.0</modelVersion>
+    <dependencies>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.google.guava</groupId>
+            <artifactId>guava</artifactId>
+        </dependency>
+    </dependencies>
+    <artifactId>converter</artifactId>
+
+
+</project>

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

@@ -0,0 +1,63 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014-2016 Ilkka Seppälä
+ * <p>
+ * 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:
+ * <p>
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * <p>
+ * 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.converter;
+
+
+import com.google.common.collect.Lists;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * The Converter pattern is a behavioral design pattern which allows a common way of bidirectional
+ * conversion between corresponding types (e.g. DTO and domain representations of the logically
+ * isomorphic types). Moreover, the pattern introduces a common way of converting a collection of
+ * objects between types.
+ */
+public class App {
+  /**
+   * Program entry point
+   *
+   * @param args command line args
+   */
+  public static void main(String[] args) {
+    Converter<UserDto, User> userConverter = new Converter<>(
+        userDto -> new User(userDto.getFirstName(), userDto.getLastName(), userDto.isActive(),
+          userDto.getEmail()),
+        user -> new UserDto(user.getFirstName(), user.getLastName(), user.isActive(), user.getUserId()));
+
+    UserDto dtoUser = new UserDto("John", "Doe", true, "whatever[at]wherever.com");
+    User user = userConverter.convertFromDto(dtoUser);
+    System.out.println("Entity converted from DTO:" + user);
+
+    ArrayList<User> users = Lists.newArrayList(new User("Camile", "Tough", false, "124sad"),
+        new User("Marti", "Luther", true, "42309fd"), new User("Kate", "Smith", true, "if0243"));
+    System.out.println("Domain entities:");
+    users.forEach(System.out::println);
+
+    System.out.println("DTO entities converted from domain:");
+    List<UserDto> dtoEntities = userConverter.createFromEntities(users);
+    dtoEntities.forEach(System.out::println);
+
+  }
+}

converter/src/main/java/com/iluwatar/converter/Converter.java

@@ -0,0 +1,86 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014-2016 Ilkka Seppälä
+ * <p>
+ * 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:
+ * <p>
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * <p>
+ * 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.converter;
+
+import java.util.Collection;
+import java.util.List;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
+/**
+ * Generic converter, thanks to Java8 features not only provides a way of generic bidirectional
+ * conversion between coresponding types, but also a common way of converting a collection of objects
+ * of the same type, reducing boilerplate code to the absolute minimum.
+ * @param <T> DTO representation's type
+ * @param <U> Domain representation's type
+ */
+public class Converter<T, U> {
+
+  private final Function<T, U> fromDto;
+  private final Function<U, T> fromEntity;
+
+  /**
+   * @param fromDto Function that converts given dto entity into the domain entity.
+   * @param fromEntity Function that converts given domain entity into the dto entity.
+   */
+  public Converter(final Function<T, U> fromDto, final Function<U, T> fromEntity) {
+    this.fromDto = fromDto;
+    this.fromEntity = fromEntity;
+  }
+
+  /**
+   * @param userDto DTO entity
+   * @return The domain representation - the result of the converting function application on dto entity.
+   */
+  public final U convertFromDto(final T userDto) {
+    return fromDto.apply(userDto);
+  }
+
+  /**
+   * @param user domain entity
+   * @return The DTO representation - the result of the converting function application on domain entity.
+   */
+  public final T convertFromEntity(final U user) {
+    return fromEntity.apply(user);
+  }
+
+  /**
+   * @param dtoUsers collection of DTO entities
+   * @return List of domain representation of provided entities retrieved by
+   *        mapping each of them with the convertion function
+   */
+  public final List<U> createFromDtos(final Collection<T> dtoUsers) {
+    return dtoUsers.stream().map(this::convertFromDto).collect(Collectors.toList());
+  }
+
+  /**
+   * @param users collection of domain entities
+   * @return List of domain representation of provided entities retrieved by
+   *        mapping each of them with the convertion function
+   */
+  public final List<T> createFromEntities(final Collection<U> users) {
+    return users.stream().map(this::convertFromEntity).collect(Collectors.toList());
+  }
+
+}

converter/src/main/java/com/iluwatar/converter/User.java

@@ -0,0 +1,86 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014-2016 Ilkka Seppälä
+ * <p>
+ * 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:
+ * <p>
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * <p>
+ * 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.converter;
+
+import java.util.Objects;
+
+/**
+ * User class
+ */
+public class User {
+  private String firstName;
+  private String lastName;
+  private boolean isActive;
+  private String userId;
+
+  /**
+   * @param firstName user's first name
+   * @param lastName  user's last name
+   * @param isActive  flag indicating whether the user is active
+   * @param userId user's identificator
+   */
+  public User(String firstName, String lastName, boolean isActive, String userId) {
+    this.firstName = firstName;
+    this.lastName = lastName;
+    this.isActive = isActive;
+    this.userId = userId;
+  }
+
+  public String getFirstName() {
+    return firstName;
+  }
+
+  public String getLastName() {
+    return lastName;
+  }
+
+  public boolean isActive() {
+    return isActive;
+  }
+
+  public String getUserId() {
+    return userId;
+  }
+
+  @Override public boolean equals(Object o) {
+    if (this == o) {
+      return true;
+    }
+    if (o == null || getClass() != o.getClass()) {
+      return false;
+    }
+    User user = (User) o;
+    return isActive == user.isActive && Objects.equals(firstName, user.firstName) && Objects
+      .equals(lastName, user.lastName) && Objects.equals(userId, user.userId);
+  }
+
+  @Override public int hashCode() {
+    return Objects.hash(firstName, lastName, isActive, userId);
+  }
+
+  @Override public String toString() {
+    return "User{" + "firstName='" + firstName + '\'' + ", lastName='" + lastName + '\''
+      + ", isActive=" + isActive + ", userId='" + userId + '\'' + '}';
+  }
+}

converter/src/main/java/com/iluwatar/converter/UserConverter.java

@@ -0,0 +1,40 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014-2016 Ilkka Seppälä
+ * <p>
+ * 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:
+ * <p>
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * <p>
+ * 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.converter;
+
+/**
+ * Example implementation of the simple User converter.
+ */
+public class UserConverter extends Converter<UserDto, User> {
+
+  /**
+   * Constructor.
+   */
+  public UserConverter() {
+    super(userDto -> new User(userDto.getFirstName(), userDto.getLastName(), userDto.isActive(),
+        userDto.getEmail()),
+        user -> new UserDto(user.getFirstName(), user.getLastName(), user.isActive(),
+        user.getUserId()));
+  }
+}

converter/src/main/java/com/iluwatar/converter/UserDto.java

@@ -0,0 +1,88 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014-2016 Ilkka Seppälä
+ * <p>
+ * 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:
+ * <p>
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * <p>
+ * 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.converter;
+
+
+import java.util.Objects;
+
+/**
+ * User DTO class
+ */
+public class UserDto {
+
+  private String firstName;
+  private String lastName;
+  private boolean isActive;
+  private String email;
+
+  /**
+   * @param firstName user's first name
+   * @param lastName  user's last name
+   * @param isActive  flag indicating whether the user is active
+   * @param email     user's email address
+   */
+  public UserDto(String firstName, String lastName, boolean isActive, String email) {
+    this.firstName = firstName;
+    this.lastName = lastName;
+    this.isActive = isActive;
+    this.email = email;
+  }
+
+  public String getFirstName() {
+    return firstName;
+  }
+
+  public String getLastName() {
+    return lastName;
+  }
+
+  public boolean isActive() {
+    return isActive;
+  }
+
+  public String getEmail() {
+    return email;
+  }
+
+  @Override public boolean equals(Object o) {
+    if (this == o) {
+      return true;
+    }
+    if (o == null || getClass() != o.getClass()) {
+      return false;
+    }
+    UserDto userDto = (UserDto) o;
+    return isActive == userDto.isActive && Objects.equals(firstName, userDto.firstName) && Objects
+      .equals(lastName, userDto.lastName) && Objects.equals(email, userDto.email);
+  }
+
+  @Override public int hashCode() {
+    return Objects.hash(firstName, lastName, isActive, email);
+  }
+
+  @Override public String toString() {
+    return "UserDto{" + "firstName='" + firstName + '\'' + ", lastName='" + lastName + '\''
+      + ", isActive=" + isActive + ", email='" + email + '\'' + '}';
+  }
+}

converter/src/test/java/com/iluwatar/converter/AppTest.java

@@ -0,0 +1,38 @@
+/**
+ * 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.converter;
+
+import org.junit.Test;
+
+/**
+ * App running test
+ */
+public class AppTest {
+
+  @Test
+  public void testMain() {
+    String[] args = {};
+    App.main(args);
+  }
+
+}

converter/src/test/java/com/iluwatar/converter/ConverterTest.java

@@ -0,0 +1,84 @@
+/**
+ * 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.converter;
+
+import com.google.common.collect.Lists;
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Random;
+
+import static junit.framework.TestCase.assertEquals;
+
+/**
+ * Tests for {@link Converter}
+ */
+public class ConverterTest {
+
+  private UserConverter userConverter = new UserConverter();
+
+  /**
+   * Tests whether a converter created of opposite functions holds equality as a bijection.
+   */
+  @Test public void testConversionsStartingFromDomain() {
+    User u1 = new User("Tom", "Hanks", true, "tom@hanks.com");
+    User u2 = userConverter.convertFromDto(userConverter.convertFromEntity(u1));
+    assertEquals(u1, u2);
+  }
+
+  /**
+   * Tests whether a converter created of opposite functions holds equality as a bijection.
+   */
+  @Test public void testConversionsStartingFromDto() {
+    UserDto u1 = new UserDto("Tom", "Hanks", true, "tom@hanks.com");
+    UserDto u2 = userConverter.convertFromEntity(userConverter.convertFromDto(u1));
+    assertEquals(u1, u2);
+  }
+
+  /**
+   * Tests the custom users converter. Thanks to Java8 lambdas, converter can be easily and
+   * cleanly instantiated allowing various different conversion strategies to be implemented.
+   */
+  @Test public void testCustomConverter() {
+    Converter<UserDto, User> converter = new Converter<>(
+        userDto -> new User(userDto.getFirstName(), userDto.getLastName(), userDto.isActive(),
+        String.valueOf(new Random().nextInt())),
+        user -> new UserDto(user.getFirstName(), user.getLastName(), user.isActive(),
+        user.getFirstName().toLowerCase() + user.getLastName().toLowerCase() + "@whatever.com"));
+    User u1 = new User("John", "Doe", false, "12324");
+    UserDto userDto = converter.convertFromEntity(u1);
+    assertEquals(userDto.getEmail(), "johndoe@whatever.com");
+  }
+
+  /**
+   * Test whether converting a collection of Users to DTO Users and then converting them back to domain
+   * users returns an equal collection.
+   */
+  @Test public void testCollectionConversion() {
+    ArrayList<User> users = Lists.newArrayList(new User("Camile", "Tough", false, "124sad"),
+        new User("Marti", "Luther", true, "42309fd"), new User("Kate", "Smith", true, "if0243"));
+    List<User> fromDtos = userConverter.createFromDtos(userConverter.createFromEntities(users));
+    assertEquals(fromDtos, users);
+  }
+}

dao/pom.xml

@@ -30,7 +30,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.15.0-SNAPSHOT</version>
+    <version>1.16.0-SNAPSHOT</version>
   </parent>
   <artifactId>dao</artifactId>
 

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

@@ -22,13 +22,16 @@
  */
 package com.iluwatar.dao;
 
+/**
+ * Customer Schema SQL Class
+ */
 public final class CustomerSchemaSql {
 
   private CustomerSchemaSql() {}
 
-  public static final String CREATE_SCHEMA_SQL = "CREATE TABLE CUSTOMERS (ID NUMBER, FNAME VARCHAR(100), " 
+  public static final String CREATE_SCHEMA_SQL = "CREATE TABLE CUSTOMERS (ID NUMBER, FNAME VARCHAR(100), "
       + "LNAME VARCHAR(100))";
-  
+
   public static final String DELETE_SCHEMA_SQL = "DROP TABLE CUSTOMERS";
-  
+
 }

dao/src/test/java/com/iluwatar/dao/CustomerTest.java

@@ -29,6 +29,9 @@ import static org.junit.Assert.assertNotEquals;
 import org.junit.Before;
 import org.junit.Test;
 
+/**
+ * Tests {@link Customer}.
+ */
 public class CustomerTest {
 
   private Customer customer;

data-mapper/pom.xml

@@ -28,7 +28,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.15.0-SNAPSHOT</version>
+		<version>1.16.0-SNAPSHOT</version>
 	</parent>
 	<artifactId>data-mapper</artifactId>
 	<dependencies>

data-mapper/src/main/java/com/iluwatar/datamapper/Student.java

@@ -21,6 +21,9 @@ package com.iluwatar.datamapper;
 
 import java.io.Serializable;
 
+/**
+ * Class defining Student
+ */
 public final class Student implements Serializable {
 
   private static final long serialVersionUID = 1L;
@@ -32,7 +35,7 @@ public final class Student implements Serializable {
 
   /**
    * Use this constructor to create a Student with all details
-   * 
+   *
    * @param studentId as unique student id
    * @param name as student name
    * @param grade as respective grade of student
@@ -46,7 +49,7 @@ public final class Student implements Serializable {
   }
 
   /**
-   * 
+   *
    * @return the student id
    */
   public int getStudentId() {
@@ -54,7 +57,7 @@ public final class Student implements Serializable {
   }
 
   /**
-   * 
+   *
    * @param studentId as unique student id
    */
   public void setStudentId(final int studentId) {
@@ -62,7 +65,7 @@ public final class Student implements Serializable {
   }
 
   /**
-   * 
+   *
    * @return name of student
    */
   public String getName() {
@@ -70,7 +73,7 @@ public final class Student implements Serializable {
   }
 
   /**
-   * 
+   *
    * @param name as 'name' of student
    */
   public void setName(final String name) {
@@ -78,7 +81,7 @@ public final class Student implements Serializable {
   }
 
   /**
-   * 
+   *
    * @return grade of student
    */
   public char getGrade() {
@@ -86,7 +89,7 @@ public final class Student implements Serializable {
   }
 
   /**
-   * 
+   *
    * @param grade as 'grade of student'
    */
   public void setGrade(final char grade) {
@@ -94,7 +97,7 @@ public final class Student implements Serializable {
   }
 
   /**
- * 
+ *
  */
   @Override
   public boolean equals(final Object inputObject) {
@@ -120,7 +123,7 @@ public final class Student implements Serializable {
   }
 
   /**
- * 
+ *
  */
   @Override
   public int hashCode() {
@@ -130,7 +133,7 @@ public final class Student implements Serializable {
   }
 
   /**
- * 
+ *
  */
   @Override
   public String toString() {

data-mapper/src/main/java/com/iluwatar/datamapper/StudentDataMapper.java

@@ -20,6 +20,9 @@ package com.iluwatar.datamapper;
 
 import java.util.Optional;
 
+/**
+ * Interface lists out the possible behaviour for all possible student mappers
+ */
 public interface StudentDataMapper {
 
   Optional<Student> find(int studentId);

data-mapper/src/main/java/com/iluwatar/datamapper/StudentDataMapperImpl.java

@@ -22,6 +22,9 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.Optional;
 
+/**
+ * Implementation of Actions on Students Data
+ */
 public final class StudentDataMapperImpl implements StudentDataMapper {
 
   /* Note: Normally this would be in the form of an actual database */

data-mapper/src/test/java/com/iluwatar/datamapper/StudentTest.java

@@ -18,17 +18,21 @@
  */
 package com.iluwatar.datamapper;
 
-import org.junit.Test;
-import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
 
+import org.junit.Test;
+
+/**
+ * Tests {@link Student}.
+ */
 public final class StudentTest {
 
   @Test
   /**
    * This API tests the equality behaviour of Student object
    * Object Equality should work as per logic defined in equals method
-   * 
+   *
    * @throws Exception if any execution error during test
    */
   public void testEquality() throws Exception {

decorator/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.15.0-SNAPSHOT</version>
+    <version>1.16.0-SNAPSHOT</version>
   </parent>
   <artifactId>decorator</artifactId>
   <dependencies>

delegation/pom.xml

@@ -30,7 +30,7 @@
     <parent>
         <artifactId>java-design-patterns</artifactId>
         <groupId>com.iluwatar</groupId>
-        <version>1.15.0-SNAPSHOT</version>
+        <version>1.16.0-SNAPSHOT</version>
     </parent>
     <modelVersion>4.0.0</modelVersion>
 

delegation/src/main/java/com/iluwatar/delegation/simple/PrinterController.java

@@ -22,6 +22,12 @@
  */
 package com.iluwatar.delegation.simple;
 
+/**
+ * Delegator Class to delegate the implementation of the Printer.
+ * This ensures two things:
+ *  - when the actual implementation of the Printer class changes the delegation will still be operational
+ *  - the actual benefit is observed when there are more than one implementors and they share a delegation control
+ */
 public class PrinterController implements Printer {
 
   private final Printer printer;

delegation/src/test/java/com/iluwatar/delegation/simple/AppTest.java

@@ -23,7 +23,9 @@
 package com.iluwatar.delegation.simple;
 
 import org.junit.Test;
-
+/**
+ * Application Test Entry
+ */
 public class AppTest {
 
   @Test

delegation/src/test/java/com/iluwatar/delegation/simple/DelegateTest.java

@@ -22,22 +22,24 @@
  */
 package com.iluwatar.delegation.simple;
 
+import static org.junit.Assert.assertEquals;
+
 import ch.qos.logback.classic.Logger;
 import ch.qos.logback.classic.spi.ILoggingEvent;
 import ch.qos.logback.core.AppenderBase;
 import com.iluwatar.delegation.simple.printers.CanonPrinter;
 import com.iluwatar.delegation.simple.printers.EpsonPrinter;
 import com.iluwatar.delegation.simple.printers.HpPrinter;
+import java.util.LinkedList;
+import java.util.List;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
 import org.slf4j.LoggerFactory;
 
-import java.util.LinkedList;
+/**
-import java.util.List;
+ * Test for Delegation Pattern
-
+ */
-import static org.junit.Assert.assertEquals;
-
 public class DelegateTest {
 
   private InMemoryAppender appender;
@@ -78,6 +80,9 @@ public class DelegateTest {
     assertEquals("Epson Printer : Test Message Printed", appender.getLastMessage());
   }
 
+  /**
+   * Logging Appender
+   */
   private class InMemoryAppender extends AppenderBase<ILoggingEvent> {
 
     private List<ILoggingEvent> log = new LinkedList<>();

dependency-injection/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.15.0-SNAPSHOT</version>
+    <version>1.16.0-SNAPSHOT</version>
   </parent>
   <artifactId>dependency-injection</artifactId>
   <dependencies>

dependency-injection/src/test/java/com/iluwatar/dependency/injection/utils/InMemoryAppender.java

@@ -30,6 +30,10 @@ import org.slf4j.LoggerFactory;
 import java.util.LinkedList;
 import java.util.List;
 
+
+/**
+ * InMemory Log Appender Util.
+ */
 public class InMemoryAppender extends AppenderBase<ILoggingEvent> {
 
   private List<ILoggingEvent> log = new LinkedList<>();

double-checked-locking/pom.xml

@@ -27,7 +27,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.15.0-SNAPSHOT</version>
+    <version>1.16.0-SNAPSHOT</version>
   </parent>
   <artifactId>double-checked-locking</artifactId>
   <dependencies>

double-dispatch/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.15.0-SNAPSHOT</version>
+    <version>1.16.0-SNAPSHOT</version>
   </parent>
   <artifactId>double-dispatch</artifactId>
   <dependencies>

double-dispatch/src/test/java/com/iluwatar/doubledispatch/CollisionTest.java

@@ -22,13 +22,14 @@
  */
 package com.iluwatar.doubledispatch;
 
-import java.util.Objects;
-
 import static org.junit.Assert.assertEquals;
 
+import java.util.Objects;
+
 /**
  * Date: 12/10/15 - 8:37 PM
- *
+ * Test for Collision
+ * @param <O> Type of GameObject
  * @author Jeroen Meulemeester
  */
 public abstract class CollisionTest<O extends GameObject> {

event-aggregator/pom.xml

@@ -28,7 +28,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.15.0-SNAPSHOT</version>
+		<version>1.16.0-SNAPSHOT</version>
 	</parent>
 	<artifactId>event-aggregator</artifactId>
 	<dependencies>

event-aggregator/src/test/java/com/iluwatar/event/aggregator/EventEmitterTest.java

@@ -22,22 +22,22 @@
  */
 package com.iluwatar.event.aggregator;
 
-import org.junit.Test;
-
-import java.util.Objects;
-import java.util.function.Function;
-import java.util.function.Supplier;
-
 import static org.mockito.Matchers.eq;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
-import static org.mockito.Mockito.verifyZeroInteractions;
 import static org.mockito.Mockito.verifyNoMoreInteractions;
+import static org.mockito.Mockito.verifyZeroInteractions;
+
+import java.util.Objects;
+import java.util.function.Function;
+import java.util.function.Supplier;
+import org.junit.Test;
 
 /**
  * Date: 12/12/15 - 10:58 PM
- *
+ * Tests for Event Emitter
+ * @param <E> Type of Event Emitter
  * @author Jeroen Meulemeester
  */
 public abstract class EventEmitterTest<E extends EventEmitter> {
@@ -115,7 +115,7 @@ public abstract class EventEmitterTest<E extends EventEmitter> {
     // The observers should not have received any additional events after the week
     verifyNoMoreInteractions(observers);
   }
-  
+
   /**
    * Go over every day of the month, and check if the event is emitted on the given day. Use an
    * event emitter without a default observer

event-asynchronous/README.md

@@ -12,11 +12,12 @@ tags:
 
 ## Intent
 The Event-based Asynchronous Pattern makes available the advantages of multithreaded applications while hiding many
-of the complex issues inherent in multithreaded design. Using a class that supports this pattern can allow you to:-
+of the complex issues inherent in multithreaded design. Using a class that supports this pattern can allow you to:
-(1) Perform time-consuming tasks, such as downloads and database operations, "in the background," without interrupting your application. 
+
-(2) Execute multiple operations simultaneously, receiving notifications when each completes. 
+1. Perform time-consuming tasks, such as downloads and database operations, "in the background," without interrupting your application.
-(3) Wait for resources to become available without stopping ("hanging") your application. 
+2. Execute multiple operations simultaneously, receiving notifications when each completes.
-(4) Communicate with pending asynchronous operations using the familiar events-and-delegates model.
+3. Wait for resources to become available without stopping ("hanging") your application.
+4. Communicate with pending asynchronous operations using the familiar events-and-delegates model.
 
 ![alt text](./etc/event-asynchronous.png "Event-based Asynchronous")
 

event-asynchronous/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.15.0-SNAPSHOT</version>
+    <version>1.16.0-SNAPSHOT</version>
   </parent>
   <artifactId>event-asynchronous</artifactId>
   <dependencies>

event-asynchronous/src/main/java/com/iluwatar/event/asynchronous/EventDoesNotExistException.java

@@ -16,6 +16,9 @@
  */
 package com.iluwatar.event.asynchronous;
 
+/**
+ * Custom Exception Class for Non Existent Event
+ */
 public class EventDoesNotExistException extends Exception {
 
   private static final long serialVersionUID = -3398463738273811509L;

event-asynchronous/src/main/java/com/iluwatar/event/asynchronous/IEvent.java

@@ -16,6 +16,10 @@
  */
 package com.iluwatar.event.asynchronous;
 
+/**
+ * Events that fulfill the start stop and list out current status behaviour
+ * follow this interface
+ */
 public interface IEvent {
 
   void start();

event-asynchronous/src/main/java/com/iluwatar/event/asynchronous/InvalidOperationException.java

@@ -16,6 +16,9 @@
  */
 package com.iluwatar.event.asynchronous;
 
+/**
+ * Type of Exception raised when the Operation being invoked is Invalid
+ */
 public class InvalidOperationException extends Exception {
 
   private static final long serialVersionUID = -6191545255213410803L;

event-asynchronous/src/main/java/com/iluwatar/event/asynchronous/LongRunningEventException.java

@@ -16,6 +16,9 @@
  */
 package com.iluwatar.event.asynchronous;
 
+/**
+ * Type of Exception raised when the Operation being invoked is Long Running
+ */
 public class LongRunningEventException extends Exception {
 
   private static final long serialVersionUID = -483423544320148809L;

event-asynchronous/src/main/java/com/iluwatar/event/asynchronous/MaxNumOfEventsAllowedException.java

@@ -16,6 +16,9 @@
  */
 package com.iluwatar.event.asynchronous;
 
+/**
+ * Type of Exception raised when the max number of allowed events is exceeded
+ */
 public class MaxNumOfEventsAllowedException extends Exception {
 
   private static final long serialVersionUID = -8430876973516292695L;

event-asynchronous/src/main/java/com/iluwatar/event/asynchronous/ThreadCompleteListener.java

@@ -16,6 +16,9 @@
  */
 package com.iluwatar.event.asynchronous;
 
+/**
+ * Interface with listener behaviour related to Thread Completion.
+ */
 public interface ThreadCompleteListener {
   void completedEventHandler(final int eventId);
 }

event-driven-architecture/pom.xml

@@ -31,7 +31,7 @@
     <parent>
         <groupId>com.iluwatar</groupId>
         <artifactId>java-design-patterns</artifactId>
-        <version>1.15.0-SNAPSHOT</version>
+        <version>1.16.0-SNAPSHOT</version>
     </parent>
 
     <artifactId>event-driven-architecture</artifactId>

event-driven-architecture/src/main/java/com/iluwatar/eda/framework/Handler.java

@@ -25,6 +25,7 @@ package com.iluwatar.eda.framework;
 /**
  * This interface can be implemented to handle different types of messages.
  * Every handler is responsible for a single of type message
+ * @param <E> Handler can handle events of type E
  */
 public interface Handler<E extends Event> {
 
@@ -35,4 +36,4 @@ public interface Handler<E extends Event> {
    * @param event the {@link Event} object to be handled.
    */
   void onEvent(E event);
-}
+}

execute-around/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.15.0-SNAPSHOT</version>
+    <version>1.16.0-SNAPSHOT</version>
   </parent>
   <artifactId>execute-around</artifactId>
   <dependencies>

facade/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.15.0-SNAPSHOT</version>
+    <version>1.16.0-SNAPSHOT</version>
   </parent>
   <artifactId>facade</artifactId>
   <dependencies>

factory-kit/pom.xml

@@ -30,7 +30,7 @@
     <parent>
         <groupId>com.iluwatar</groupId>
         <artifactId>java-design-patterns</artifactId>
-        <version>1.15.0-SNAPSHOT</version>
+        <version>1.16.0-SNAPSHOT</version>
     </parent>
     <artifactId>factory-kit</artifactId>
     <dependencies>

factory-kit/src/main/java/com/iluwatar/factorykit/Axe.java

@@ -22,6 +22,9 @@
  */
 package com.iluwatar.factorykit;
 
+/**
+ * Class representing Axe
+ */
 public class Axe implements Weapon {
   @Override
   public String toString() {

factory-kit/src/main/java/com/iluwatar/factorykit/Bow.java

@@ -22,6 +22,9 @@
  */
 package com.iluwatar.factorykit;
 
+/**
+ * Class representing Bows
+ */
 public class Bow implements Weapon {
   @Override
   public String toString() {

factory-kit/src/main/java/com/iluwatar/factorykit/Spear.java

@@ -21,7 +21,9 @@
  * THE SOFTWARE.
  */
 package com.iluwatar.factorykit;
-
+/**
+ * Class representing Spear
+ */
 public class Spear implements Weapon {
   @Override
   public String toString() {

factory-kit/src/main/java/com/iluwatar/factorykit/Sword.java

@@ -21,7 +21,9 @@
  * THE SOFTWARE.
  */
 package com.iluwatar.factorykit;
-
+/**
+ * Class representing Swords
+ */
 public class Sword implements Weapon {
   @Override
   public String toString() {

factory-kit/src/test/java/com/iluwatar/factorykit/app/AppTest.java

@@ -25,6 +25,9 @@ package com.iluwatar.factorykit.app;
 import com.iluwatar.factorykit.App;
 import org.junit.Test;
 
+/**
+ * Application Test Entrypoint
+ */
 public class AppTest {
 
   @Test

factory-kit/src/test/java/com/iluwatar/factorykit/factorykit/FactoryKitTest.java

@@ -1,4 +1,4 @@
-/**
+  /**
  * The MIT License
  * Copyright (c) 2014-2016 Ilkka Seppälä
  *
@@ -22,12 +22,19 @@
  */
 package com.iluwatar.factorykit.factorykit;
 
-import com.iluwatar.factorykit.*;
-import org.junit.Before;
-import org.junit.Test;
-
 import static org.junit.Assert.assertTrue;
 
+import com.iluwatar.factorykit.Axe;
+import com.iluwatar.factorykit.Spear;
+import com.iluwatar.factorykit.Sword;
+import com.iluwatar.factorykit.Weapon;
+import com.iluwatar.factorykit.WeaponFactory;
+import com.iluwatar.factorykit.WeaponType;
+import org.junit.Before;
+import org.junit.Test;
+/**
+ *  Test Factory Kit Pattern
+ */
 public class FactoryKitTest {
 
   private WeaponFactory factory;

factory-method/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.15.0-SNAPSHOT</version>
+    <version>1.16.0-SNAPSHOT</version>
   </parent>
   <artifactId>factory-method</artifactId>
   <dependencies>

feature-toggle/pom.xml

@@ -30,7 +30,7 @@
     <parent>
         <artifactId>java-design-patterns</artifactId>
         <groupId>com.iluwatar</groupId>
-        <version>1.15.0-SNAPSHOT</version>
+        <version>1.16.0-SNAPSHOT</version>
     </parent>
     <modelVersion>4.0.0</modelVersion>
 

feature-toggle/src/test/java/com/iluwatar/featuretoggle/pattern/propertiesversion/PropertiesFeatureToggleVersionTest.java

@@ -23,16 +23,18 @@
 
 package com.iluwatar.featuretoggle.pattern.propertiesversion;
 
-import com.iluwatar.featuretoggle.pattern.Service;
-import com.iluwatar.featuretoggle.user.User;
-import org.junit.Test;
-
-import java.util.Properties;
-
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
+import com.iluwatar.featuretoggle.pattern.Service;
+import com.iluwatar.featuretoggle.user.User;
+import java.util.Properties;
+import org.junit.Test;
+
+/**
+ * Test Properties Toggle
+ */
 public class PropertiesFeatureToggleVersionTest {
 
   @Test(expected = IllegalArgumentException.class)
@@ -66,4 +68,4 @@ public class PropertiesFeatureToggleVersionTest {
     final String welcomeMessage = service.getWelcomeMessage(new User("Jamie No Code"));
     assertEquals("Welcome to the application.", welcomeMessage);
   }
-}
+}

feature-toggle/src/test/java/com/iluwatar/featuretoggle/pattern/tieredversion/TieredFeatureToggleVersionTest.java

@@ -22,15 +22,18 @@
  */
 package com.iluwatar.featuretoggle.pattern.tieredversion;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
 import com.iluwatar.featuretoggle.pattern.Service;
 import com.iluwatar.featuretoggle.user.User;
 import com.iluwatar.featuretoggle.user.UserGroup;
 import org.junit.Before;
 import org.junit.Test;
 
-import static org.junit.Assert.assertEquals;
+/**
-import static org.junit.Assert.assertTrue;
+ * Test Tiered Feature Toggle
-
+ */
 public class TieredFeatureToggleVersionTest {
 
   final User paidUser = new User("Jamie Coder");
@@ -61,4 +64,4 @@ public class TieredFeatureToggleVersionTest {
   public void testIsEnhancedAlwaysTrueAsTiered() throws Exception {
     assertTrue(service.isEnhanced());
   }
-}
+}

feature-toggle/src/test/java/com/iluwatar/featuretoggle/user/UserGroupTest.java

@@ -22,11 +22,14 @@
  */
 package com.iluwatar.featuretoggle.user;
 
-import org.junit.Test;
-
 import static junit.framework.TestCase.assertFalse;
 import static org.junit.Assert.assertTrue;
 
+import org.junit.Test;
+
+/**
+ * Test User Group specific feature
+ */
 public class UserGroupTest {
 
   @Test
@@ -56,4 +59,4 @@ public class UserGroupTest {
     UserGroup.addUserToPaidGroup(user);
     UserGroup.addUserToFreeGroup(user);
   }
-}
+}