Reached milestone 1.15.0

Checkstyle improvements #539 : Added JavaDocType Rule

abstract-document/pom.xml

@@ -29,7 +29,7 @@
     <parent>
         <artifactId>java-design-patterns</artifactId>
         <groupId>com.iluwatar</groupId>
-        <version>1.14.0</version>
+        <version>1.15.0</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>1.14.0</version>
+    <version>1.15.0</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>1.14.0</version>
+    <version>1.15.0</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>1.14.0</version>
+        <version>1.15.0</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>1.14.0</version>
+        <version>1.15.0</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>1.14.0</version>
+        <version>1.15.0</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>1.14.0</version>
+        <version>1.15.0</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>1.14.0</version>
+    <version>1.15.0</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>1.14.0</version>
+    <version>1.15.0</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>1.14.0</version>
+    <version>1.15.0</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>1.14.0</version>
+    <version>1.15.0</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>1.14.0</version>
+    <version>1.15.0</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>1.15.0</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>1.14.0</version>
+    <version>1.15.0</version>
   </parent>
   <artifactId>bridge</artifactId>
   <dependencies>

builder/etc/builder.urm.puml

@@ -86,15 +86,15 @@ package com.iluwatar.builder {
     + values() : Weapon[] {static}
   }
 }
-Hero -->  "-profession" Profession
 Builder ..+ Hero
+Hero -->  "-profession" Profession
 Hero -->  "-armor" Armor
+Builder -->  "-hairColor" HairColor
 Builder -->  "-weapon" Weapon
 Builder -->  "-hairType" HairType
-Builder -->  "-hairColor" HairColor
 Hero -->  "-hairColor" HairColor
 Builder -->  "-profession" Profession
-Hero -->  "-weapon" Weapon
 Hero -->  "-hairType" HairType
+Hero -->  "-weapon" Weapon
 Builder -->  "-armor" Armor
 @enduml

builder/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.14.0</version>
+    <version>1.15.0</version>
   </parent>
   <artifactId>builder</artifactId>
   <dependencies>

business-delegate/etc/business-delegate.urm.puml

@@ -46,8 +46,8 @@ package com.iluwatar.business.delegate {
     + values() : ServiceType[] {static}
   }
 }
-BusinessDelegate -->  "-serviceType" ServiceType
 BusinessLookup -->  "-ejbService" EjbService
+BusinessDelegate -->  "-serviceType" ServiceType
 Client -->  "-businessDelegate" BusinessDelegate
 BusinessDelegate -->  "-businessService" BusinessService
 BusinessDelegate -->  "-lookupService" BusinessLookup

business-delegate/pom.xml

@@ -30,7 +30,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.14.0</version>
+		<version>1.15.0</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>1.14.0</version>
+    <version>1.15.0</version>
   </parent>
   <artifactId>caching</artifactId>
   <dependencies>

caching/src/main/java/com/iluwatar/caching/LruCache.java

@@ -167,7 +167,7 @@ public class LruCache {
    * Returns cache data in list form.
    */
   public List<UserAccount> getCacheDataInListForm() {
-    ArrayList<UserAccount> listOfCacheData = new ArrayList<>();
+    List<UserAccount> listOfCacheData = new ArrayList<>();
     Node temp = head;
     while (temp != null) {
       listOfCacheData.add(temp.userAccount);

callback/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.14.0</version>
+    <version>1.15.0</version>
   </parent>
   <artifactId>callback</artifactId>
   <dependencies>

chain/etc/chain.urm.puml

@@ -53,8 +53,8 @@ package com.iluwatar.chain {
   }
 }
 RequestHandler -->  "-next" RequestHandler
-OrcKing -->  "-chain" RequestHandler
 Request -->  "-requestType" RequestType
+OrcKing -->  "-chain" RequestHandler
 OrcCommander --|> RequestHandler 
 OrcOfficer --|> RequestHandler 
 OrcSoldier --|> RequestHandler 

chain/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.14.0</version>
+    <version>1.15.0</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>1.14.0</version>
+    <version>1.15.0</version>
   </parent>
   <artifactId>command</artifactId>
   <dependencies>

composite/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.14.0</version>
+    <version>1.15.0</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>1.15.0</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/etc/dao.urm.puml

@@ -34,9 +34,10 @@ package com.iluwatar.dao {
     + getById(int) : Optional<Customer> {abstract}
     + update(Customer) : boolean {abstract}
   }
-  interface CustomerSchemaSql {
+  class CustomerSchemaSql {
     + CREATE_SCHEMA_SQL : String {static}
     + DELETE_SCHEMA_SQL : String {static}
+    - CustomerSchemaSql()
   }
   class DbCustomerDao {
     - dataSource : DataSource

dao/pom.xml

@@ -30,7 +30,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.14.0</version>
+    <version>1.15.0</version>
   </parent>
   <artifactId>dao</artifactId>
 

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

@@ -22,10 +22,16 @@
  */
 package com.iluwatar.dao;
 
-public interface CustomerSchemaSql {
+/**
+ * Customer Schema SQL Class
+ */
+public final class CustomerSchemaSql {
 
-  String CREATE_SCHEMA_SQL = "CREATE TABLE CUSTOMERS (ID NUMBER, FNAME VARCHAR(100), " 
+  private CustomerSchemaSql() {}
+
+  public static final String CREATE_SCHEMA_SQL = "CREATE TABLE CUSTOMERS (ID NUMBER, FNAME VARCHAR(100), "
       + "LNAME VARCHAR(100))";
-  
-  String DELETE_SCHEMA_SQL = "DROP TABLE CUSTOMERS";
+
+  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>1.14.0</version>
+		<version>1.15.0</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>1.14.0</version>
+    <version>1.15.0</version>
   </parent>
   <artifactId>decorator</artifactId>
   <dependencies>

delegation/pom.xml

@@ -30,7 +30,7 @@
     <parent>
         <artifactId>java-design-patterns</artifactId>
         <groupId>com.iluwatar</groupId>
-        <version>1.14.0</version>
+        <version>1.15.0</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;
-
-import static org.junit.Assert.assertEquals;
-
+/**
+ * Test for Delegation Pattern
+ */
 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>1.14.0</version>
+    <version>1.15.0</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>1.14.0</version>
+    <version>1.15.0</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>1.14.0</version>
+    <version>1.15.0</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>1.14.0</version>
+		<version>1.15.0</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:-
-(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. 
-(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.
+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.
+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>1.14.0</version>
+    <version>1.15.0</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/etc/event-driven-architecture.urm.puml

@@ -54,8 +54,8 @@ package com.iluwatar.eda {
     + main(args : String[]) {static}
   }
 }
-UserCreatedEvent -->  "-user" User
 UserUpdatedEvent -->  "-user" User
+UserCreatedEvent -->  "-user" User
 AbstractEvent ..|> Event 
 UserCreatedEvent --|> AbstractEvent 
 UserUpdatedEvent --|> AbstractEvent 

event-driven-architecture/pom.xml

@@ -31,7 +31,7 @@
     <parent>
         <groupId>com.iluwatar</groupId>
         <artifactId>java-design-patterns</artifactId>
-        <version>1.14.0</version>
+        <version>1.15.0</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>1.14.0</version>
+    <version>1.15.0</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>1.14.0</version>
+    <version>1.15.0</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>1.14.0</version>
+        <version>1.15.0</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/main/java/com/iluwatar/factorykit/WeaponFactory.java

@@ -23,6 +23,7 @@
 package com.iluwatar.factorykit;
 
 import java.util.HashMap;
+import java.util.Map;
 import java.util.function.Consumer;
 import java.util.function.Supplier;
 
@@ -48,7 +49,7 @@ public interface WeaponFactory {
    * @return factory with specified {@link Builder}s
    */
   static WeaponFactory factory(Consumer<Builder> consumer) {
-    HashMap<WeaponType, Supplier<Weapon>> map = new HashMap<>();
+    Map<WeaponType, Supplier<Weapon>> map = new HashMap<>();
     consumer.accept(map::put);
     return name -> map.get(name).get();
   }