Reach milestone 1.16.0

Refactored Function<Integer,T> to IntFunction<T>

abstract-document/pom.xml

@@ -29,7 +29,7 @@
     <parent>
         <artifactId>java-design-patterns</artifactId>
         <groupId>com.iluwatar</groupId>
-        <version>1.14.0</version>
+        <version>1.16.0</version>
     </parent>
     <artifactId>abstract-document</artifactId>
     <dependencies>

abstract-factory/README.md

@@ -27,6 +27,22 @@ Use the Abstract Factory pattern when
 * a system should be configured with one of multiple families of products
 * a family of related product objects is designed to be used together, and you need to enforce this constraint
 * you want to provide a class library of products, and you want to reveal just their interfaces, not their implementations
+* the lifetime of the dependency is conceptually shorter than the lifetime of the consumer.
+*	you need a run-time value to construct a particular dependency
+*	you want to decide which product to call from a family at runtime.
+*	you need to supply one or more parameters only known at run-time before you can resolve a dependency.
+
+## Use Cases:	
+
+*	Selecting to call the appropriate implementation of FileSystemAcmeService or DatabaseAcmeService or NetworkAcmeService at runtime.
+*	Unit test case writing becomes much easier
+
+## Consequences:
+
+*	Dependency injection in java hides the service class dependencies that can lead to runtime errors that would have been caught at compile time.
+
+
+
 
 ## Real world examples
 

abstract-factory/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.14.0</version>
+    <version>1.16.0</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/README.md

@@ -21,6 +21,9 @@ incompatible interfaces.
 
 ![alt text](./etc/adapter.png "Adapter")
 
+## General usage of Adapter Pattern: 
++ Wrappers used to adopt 3rd parties libraries and frameworks - most of the applications using third party libraries use adapters as a middle layer between the application and the 3rd party library to decouple the application from the library. If another library has to be used only an adapter for the new library is required without having to change the application code.
+
 ## Applicability
 Use the Adapter pattern when
 
@@ -28,6 +31,19 @@ Use the Adapter pattern when
 * you want to create a reusable class that cooperates with unrelated or unforeseen classes, that is, classes that don't necessarily have compatible interfaces
 * you need to use several existing subclasses, but it's impractical to adapt their interface by subclassing every one. An object adapter can adapt the interface of its parent class.
 
+## Consequences:
+Class and object adapters have different trade-offs. A class adapter
+
+*	adapts Adaptee to Target by committing to a concrete Adaptee class. As a consequence, a class adapter won’t work when we want to adapt a class and all its subclasses.
+*	let’s Adapter override some of Adaptee’s behavior, since Adapter is a subclass of Adaptee.
+*	introduces only one object, and no additional pointer indirection is needed to get to the adaptee.
+
+An object adapter	
+
+*	let’s a single Adapter work with many Adaptees—that is, the Adaptee itself and all of its subclasses (if any). The Adapter can also add functionality to all Adaptees at once.
+*	makes it harder to override Adaptee behavior. It will require subclassing Adaptee and making Adapter refer to the subclass rather than the Adaptee itself.
+
+
 ## Real world examples
 
 * [java.util.Arrays#asList()](http://docs.oracle.com/javase/8/docs/api/java/util/Arrays.html#asList%28T...%29)

adapter/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.14.0</version>
+    <version>1.16.0</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>1.16.0</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>1.16.0</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>1.16.0</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>1.16.0</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>1.16.0</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>1.16.0</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>1.16.0</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>1.16.0</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>1.16.0</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>1.16.0</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>1.16.0</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>1.16.0</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>1.16.0</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>1.16.0</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>1.16.0</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>1.16.0</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>1.16.0</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>1.16.0</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>1.16.0</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>1.16.0</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-bus/.gitignore

@@ -0,0 +1 @@
+/target

data-bus/README.md

@@ -0,0 +1,33 @@
+---
+layout: pattern
+title: Data Bus
+folder: data-bus
+permalink: /patterns/data-bus/
+
+categories: Architectural
+tags:
+ - Java
+ - Difficulty-Intermediate
+---
+
+## Intent
+
+Allows send of messages/events between components of an application
+without them needing to know about each other. They only need to know
+about the type of the message/event being sent.
+
+![data bus pattern uml diagram](./etc/data-bus.urm.png "Data Bus pattern")
+
+## Applicability
+Use Data Bus pattern when
+
+* you want your components to decide themselves which messages/events they want to receive
+* you want to have many-to-many communication
+* you want your components to know nothing about each other
+
+## Related Patterns
+Data Bus is similar to
+
+* Mediator pattern with Data Bus Members deciding for themselves if they want to accept any given message
+* Observer pattern but supporting many-to-many communication
+* Publish/Subscribe pattern with the Data Bus decoupling the publisher and the subscriber

data-bus/etc/data-bus.urm.puml

@@ -0,0 +1,77 @@
+@startuml
+package com.iluwatar.databus {
+  class AbstractDataType {
+    - dataBus : DataBus
+    + AbstractDataType()
+    + getDataBus() : DataBus
+    + setDataBus(dataBus : DataBus)
+  }
+  ~class App {
+    - log : Logger {static}
+    ~ App()
+    + main(args : String[]) {static}
+  }
+  class DataBus {
+    - INSTANCE : DataBus {static}
+    - listeners : Set<Member>
+    + DataBus()
+    + getInstance() : DataBus {static}
+    + publish(event : DataType)
+    + subscribe(member : Member)
+    + unsubscribe(member : Member)
+  }
+  interface DataType {
+    + getDataBus() : DataBus {abstract}
+    + setDataBus(DataBus) {abstract}
+  }
+  interface Member {
+    + accept(DataType) {abstract}
+  }
+}
+package com.iluwatar.databus.data {
+  class MessageData {
+    - message : String
+    + MessageData(message : String)
+    + getMessage() : String
+    + of(message : String) : DataType {static}
+  }
+  class StartingData {
+    - when : LocalDateTime
+    + StartingData(when : LocalDateTime)
+    + getWhen() : LocalDateTime
+    + of(when : LocalDateTime) : DataType {static}
+  }
+  class StoppingData {
+    - when : LocalDateTime
+    + StoppingData(when : LocalDateTime)
+    + getWhen() : LocalDateTime
+    + of(when : LocalDateTime) : DataType {static}
+  }
+}
+package com.iluwatar.databus.members {
+  class CounterMember {
+    - log : Logger {static}
+    - name : String
+    + CounterMember(name : String)
+    + accept(data : DataType)
+    - handleEvent(data : MessageData)
+  }
+  class StatusMember {
+    - id : int
+    - log : Logger {static}
+    + StatusMember(id : int)
+    + accept(data : DataType)
+    - handleEvent(data : StartingData)
+    - handleEvent(data : StoppingData)
+  }
+}
+AbstractDataType -->  "-dataBus" DataBus
+DataBus -->  "-INSTANCE" DataBus
+DataBus -->  "-listeners" Member
+AbstractDataType ..|> DataType 
+MessageData --|> AbstractDataType 
+StartingData --|> AbstractDataType 
+StoppingData --|> AbstractDataType 
+CounterMember ..|> Member 
+StatusMember ..|> Member 
+@enduml

data-bus/pom.xml

@@ -0,0 +1,51 @@
+<?xml version="1.0"?>
+<!--
+
+    The MIT License
+    Copyright (c) 2014-2016 Ilkka Seppälä
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to deal
+    in the Software without restriction, including without limitation the rights
+    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+    copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in
+    all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+    THE SOFTWARE.
+
+-->
+<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
+         xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+    <modelVersion>4.0.0</modelVersion>
+    <properties>
+        <lombok.version>1.16.14</lombok.version>
+    </properties>
+    <parent>
+        <groupId>com.iluwatar</groupId>
+        <artifactId>java-design-patterns</artifactId>
+        <version>1.16.0</version>
+    </parent>
+    <artifactId>data-bus</artifactId>
+    <dependencies>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.mockito</groupId>
+            <artifactId>mockito-core</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+</project>

data-bus/src/main/java/com/iluwatar/databus/AbstractDataType.java

@@ -0,0 +1,67 @@
+/**
+ * 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.
+ */
+/*
+The MIT License (MIT)
+
+Copyright (c) 2016 Paul Campbell
+
+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.databus;
+
+/**
+ * Base for data to send via the Data-Bus.
+ *
+ * @author Paul Campbell (pcampbell@kemitix.net)
+ */
+public class AbstractDataType implements DataType {
+
+  private DataBus dataBus;
+
+  @Override
+  public DataBus getDataBus() {
+    return dataBus;
+  }
+
+  @Override
+  public void setDataBus(DataBus dataBus) {
+    this.dataBus = dataBus;
+  }
+}

data-bus/src/main/java/com/iluwatar/databus/App.java

@@ -0,0 +1,79 @@
+/**
+ * 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.databus;
+
+import com.iluwatar.databus.data.MessageData;
+import com.iluwatar.databus.data.StartingData;
+import com.iluwatar.databus.data.StoppingData;
+import com.iluwatar.databus.members.MessageCollectorMember;
+import com.iluwatar.databus.members.StatusMember;
+
+import java.time.LocalDateTime;
+
+/**
+ * The Data Bus pattern
+ * <p>
+ * <p>{@see http://wiki.c2.com/?DataBusPattern}</p>
+ * <p>
+ * <p>The Data-Bus pattern provides a method where different parts of an application may
+ * pass messages between each other without needing to be aware of the other's existence.</p>
+ * <p>Similar to the {@code ObserverPattern}, members register themselves with the {@link DataBus}
+ * and may then receive each piece of data that is published to the Data-Bus. The member
+ * may react to any given message or not.</p>
+ * <p>It allows for Many-to-Many distribution of data, as there may be any number of
+ * publishers to a Data-Bus, and any number of members receiving the data. All members
+ * will receive the same data, the order each receives a given piece of data, is an
+ * implementation detail.</p>
+ * <p>Members may unsubscribe from the Data-Bus to stop receiving data.</p>
+ * <p>This example of the pattern implements a Synchronous Data-Bus, meaning that
+ * when data is published to the Data-Bus, the publish method will not return until
+ * all members have received the data and returned.</p>
+ * <p>The {@link DataBus} class is a Singleton.</p>
+ * <p>Members of the Data-Bus must implement the {@link Member} interface.</p>
+ * <p>Data to be published via the Data-Bus must implement the {@link DataType} interface.</p>
+ * <p>The {@code data} package contains example {@link DataType} implementations.</p>
+ * <p>The {@code members} package contains example {@link Member} implementations.</p>
+ * <p>The {@link StatusMember} demonstrates using the DataBus to publish a message
+ * to the Data-Bus when it receives a message.</p>
+ *
+ * @author Paul Campbell (pcampbell@kemitix.net)
+ */
+class App {
+
+  public static void main(String[] args) {
+    final DataBus bus = DataBus.getInstance();
+    bus.subscribe(new StatusMember(1));
+    bus.subscribe(new StatusMember(2));
+    final MessageCollectorMember foo = new MessageCollectorMember("Foo");
+    final MessageCollectorMember bar = new MessageCollectorMember("Bar");
+    bus.subscribe(foo);
+    bus.publish(StartingData.of(LocalDateTime.now()));
+    bus.publish(MessageData.of("Only Foo should see this"));
+    bus.subscribe(bar);
+    bus.publish(MessageData.of("Foo and Bar should see this"));
+    bus.unsubscribe(foo);
+    bus.publish(MessageData.of("Only Bar should see this"));
+    bus.publish(StoppingData.of(LocalDateTime.now()));
+  }
+}

data-bus/src/main/java/com/iluwatar/databus/DataBus.java

@@ -0,0 +1,73 @@
+/**
+ * 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.databus;
+
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * The Data-Bus implementation.
+ *
+ * <p>This implementation uses a Singleton.</p>
+ *
+ * @author Paul Campbell (pcampbell@kemitix.net)
+ */
+public class DataBus {
+
+  private static final DataBus INSTANCE = new DataBus();
+
+  private final Set<Member> listeners = new HashSet<>();
+
+  public static DataBus getInstance() {
+    return INSTANCE;
+  }
+
+  /**
+   * Register a member with the data-bus to start receiving events.
+   *
+   * @param member The member to register
+   */
+  public void subscribe(final Member member) {
+    this.listeners.add(member);
+  }
+
+  /**
+   * Deregister a member to stop receiving events.
+   *
+   * @param member The member to deregister
+   */
+  public void unsubscribe(final Member member) {
+    this.listeners.remove(member);
+  }
+
+  /**
+   * Publish and event to all members.
+   *
+   * @param event The event
+   */
+  public void publish(final DataType event) {
+    event.setDataBus(this);
+    listeners.forEach(listener -> listener.accept(event));
+  }
+}

data-bus/src/main/java/com/iluwatar/databus/DataType.java

@@ -0,0 +1,70 @@
+/**
+ * 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.
+ */
+/*
+The MIT License (MIT)
+
+Copyright (c) 2016 Paul Campbell
+
+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.databus;
+
+/**
+ * Events are sent via the Data-Bus.
+ *
+ * @author Paul Campbell (pcampbell@kemitix.net)
+ */
+
+public interface DataType {
+
+  /**
+   * Returns the data-bus the event is being sent on.
+   *
+   * @return The data-bus
+   */
+  DataBus getDataBus();
+
+  /**
+   * Set the data-bus the event will be sent on.
+   *
+   * @param dataBus The data-bus
+   */
+  void setDataBus(DataBus dataBus);
+}

data-bus/src/main/java/com/iluwatar/databus/Member.java

@@ -0,0 +1,59 @@
+/**
+ * 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.
+ */
+/*
+The MIT License (MIT)
+
+Copyright (c) 2016 Paul Campbell
+
+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.databus;
+
+import java.util.function.Consumer;
+
+/**
+ * Members receive events from the Data-Bus.
+ *
+ * @author Paul Campbell (pcampbell@kemitix.net)
+ */
+public interface Member extends Consumer<DataType> {
+
+  void accept(DataType event);
+}

data-bus/src/main/java/com/iluwatar/databus/data/MessageData.java

@@ -0,0 +1,49 @@
+/**
+ * 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.databus.data;
+
+import com.iluwatar.databus.AbstractDataType;
+import com.iluwatar.databus.DataType;
+
+/**
+ * An event raised when a string message is sent.
+ *
+ * @author Paul Campbell (pcampbell@kemitix.net)
+ */
+public class MessageData extends AbstractDataType {
+
+  private final String message;
+
+  public MessageData(String message) {
+    this.message = message;
+  }
+
+  public String getMessage() {
+    return message;
+  }
+
+  public static DataType of(final String message) {
+    return new MessageData(message);
+  }
+}

data-bus/src/main/java/com/iluwatar/databus/data/StartingData.java

@@ -0,0 +1,51 @@
+/**
+ * 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.databus.data;
+
+import com.iluwatar.databus.AbstractDataType;
+import com.iluwatar.databus.DataType;
+
+import java.time.LocalDateTime;
+
+/**
+ * An event raised when applications starts, containing the start time of the application.
+ *
+ * @author Paul Campbell (pcampbell@kemitix.net)
+ */
+public class StartingData extends AbstractDataType {
+
+  private final LocalDateTime when;
+
+  public StartingData(LocalDateTime when) {
+    this.when = when;
+  }
+
+  public LocalDateTime getWhen() {
+    return when;
+  }
+
+  public static DataType of(final LocalDateTime when) {
+    return new StartingData(when);
+  }
+}

data-bus/src/main/java/com/iluwatar/databus/data/StoppingData.java

@@ -0,0 +1,51 @@
+/**
+ * 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.databus.data;
+
+import com.iluwatar.databus.AbstractDataType;
+import com.iluwatar.databus.DataType;
+
+import java.time.LocalDateTime;
+
+/**
+ * An event raised when applications stops, containing the stop time of the application.
+ *
+ * @author Paul Campbell (pcampbell@kemitix.net)
+ */
+public class StoppingData extends AbstractDataType {
+
+  private final LocalDateTime when;
+
+  public StoppingData(LocalDateTime when) {
+    this.when = when;
+  }
+
+  public LocalDateTime getWhen() {
+    return when;
+  }
+
+  public static DataType of(final LocalDateTime when) {
+    return new StoppingData(when);
+  }
+}

data-bus/src/main/java/com/iluwatar/databus/members/MessageCollectorMember.java

@@ -0,0 +1,67 @@
+/**
+ * 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.databus.members;
+
+import com.iluwatar.databus.DataType;
+import com.iluwatar.databus.Member;
+import com.iluwatar.databus.data.MessageData;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.logging.Logger;
+
+/**
+ * Receiver of Data-Bus events that collects the messages from each {@link MessageData}.
+ *
+ * @author Paul Campbell (pcampbell@kemitix.net)
+ */
+public class MessageCollectorMember implements Member {
+
+  private static final Logger LOGGER = Logger.getLogger(MessageCollectorMember.class.getName());
+
+  private final String name;
+
+  private List<String> messages = new ArrayList<>();
+
+  public MessageCollectorMember(String name) {
+    this.name = name;
+  }
+
+  @Override
+  public void accept(final DataType data) {
+    if (data instanceof MessageData) {
+      handleEvent((MessageData) data);
+    }
+  }
+
+  private void handleEvent(MessageData data) {
+    LOGGER.info(String.format("%s sees message %s", name, data.getMessage()));
+    messages.add(data.getMessage());
+  }
+
+  public List<String> getMessages() {
+    return Collections.unmodifiableList(messages);
+  }
+}

data-bus/src/main/java/com/iluwatar/databus/members/StatusMember.java

@@ -0,0 +1,82 @@
+/**
+ * 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.databus.members;
+
+import com.iluwatar.databus.DataType;
+import com.iluwatar.databus.Member;
+import com.iluwatar.databus.data.MessageData;
+import com.iluwatar.databus.data.StartingData;
+import com.iluwatar.databus.data.StoppingData;
+
+import java.time.LocalDateTime;
+import java.util.logging.Logger;
+
+/**
+ * Receiver of Data-Bus events.
+ *
+ * @author Paul Campbell (pcampbell@kemitix.net)
+ */
+public class StatusMember implements Member {
+
+  private static final Logger LOGGER = Logger.getLogger(StatusMember.class.getName());
+
+  private final int id;
+
+  private LocalDateTime started;
+
+  private LocalDateTime stopped;
+
+  public StatusMember(int id) {
+    this.id = id;
+  }
+
+  @Override
+  public void accept(final DataType data) {
+    if (data instanceof StartingData) {
+      handleEvent((StartingData) data);
+    } else if (data instanceof StoppingData) {
+      handleEvent((StoppingData) data);
+    }
+  }
+
+  private void handleEvent(StartingData data) {
+    started = data.getWhen();
+    LOGGER.info(String.format("Receiver #%d sees application started at %s", id, started));
+  }
+
+  private void handleEvent(StoppingData data) {
+    stopped = data.getWhen();
+    LOGGER.info(String.format("Receiver #%d sees application stopping at %s", id, stopped));
+    LOGGER.info(String.format("Receiver #%d sending goodbye message", id));
+    data.getDataBus().publish(MessageData.of(String.format("Goodbye cruel world from #%d!", id)));
+  }
+
+  public LocalDateTime getStarted() {
+    return started;
+  }
+
+  public LocalDateTime getStopped() {
+    return stopped;
+  }
+}

data-bus/src/test/java/com/iluwatar/databus/DataBusTest.java

@@ -0,0 +1,74 @@
+/**
+ * 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.databus;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+
+import static org.mockito.BDDMockito.then;
+import static org.mockito.Mockito.never;
+
+/**
+ * Tests for {@link DataBus}.
+ *
+ * @author Paul Campbell (pcampbell@kemitix.net)
+ */
+public class DataBusTest {
+
+  @Mock
+  private Member member;
+
+  @Mock
+  private DataType event;
+
+  @Before
+  public void setUp() {
+    MockitoAnnotations.initMocks(this);
+  }
+
+  @Test
+  public void publishedEventIsReceivedBySubscribedMember() {
+    //given
+    final DataBus dataBus = DataBus.getInstance();
+    dataBus.subscribe(member);
+    //when
+    dataBus.publish(event);
+    //then
+    then(member).should().accept(event);
+  }
+
+  @Test
+  public void publishedEventIsNotReceivedByMemberAfterUnsubscribing() {
+    //given
+    final DataBus dataBus = DataBus.getInstance();
+    dataBus.subscribe(member);
+    dataBus.unsubscribe(member);
+    //when
+    dataBus.publish(event);
+    //then
+    then(member).should(never()).accept(event);
+  }
+
+}

data-bus/src/test/java/com/iluwatar/databus/members/MessageCollectorMemberTest.java

@@ -0,0 +1,62 @@
+/**
+ * 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.databus.members;
+
+import com.iluwatar.databus.data.MessageData;
+import com.iluwatar.databus.data.StartingData;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.time.LocalDateTime;
+
+/**
+ * Tests for {@link MessageCollectorMember}.
+ *
+ * @author Paul Campbell (pcampbell@kemitix.net)
+ */
+public class MessageCollectorMemberTest {
+
+  @Test
+  public void collectMessageFromMessageData() {
+    //given
+    final String message = "message";
+    final MessageData messageData = new MessageData(message);
+    final MessageCollectorMember collector = new MessageCollectorMember("collector");
+    //when
+    collector.accept(messageData);
+    //then
+    Assert.assertTrue(collector.getMessages().contains(message));
+  }
+
+  @Test
+  public void collectIgnoresMessageFromOtherDataTypes() {
+    //given
+    final StartingData startingData = new StartingData(LocalDateTime.now());
+    final MessageCollectorMember collector = new MessageCollectorMember("collector");
+    //when
+    collector.accept(startingData);
+    //then
+    Assert.assertEquals(0, collector.getMessages().size());
+  }
+
+}

data-bus/src/test/java/com/iluwatar/databus/members/StatusMemberTest.java

@@ -0,0 +1,79 @@
+/**
+ * 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.databus.members;
+
+import com.iluwatar.databus.DataBus;
+import com.iluwatar.databus.data.MessageData;
+import com.iluwatar.databus.data.StartingData;
+import com.iluwatar.databus.data.StoppingData;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.time.LocalDateTime;
+import java.time.Month;
+
+/**
+ * Tests for {@link StatusMember}.
+ *
+ * @author Paul Campbell (pcampbell@kemitix.net)
+ */
+public class StatusMemberTest {
+
+  @Test
+  public void statusRecordsTheStartTime() {
+    //given
+    final LocalDateTime startTime = LocalDateTime.of(2017, Month.APRIL, 1, 19, 9);
+    final StartingData startingData = new StartingData(startTime);
+    final StatusMember statusMember = new StatusMember(1);
+    //when
+    statusMember.accept(startingData);
+    //then
+    Assert.assertEquals(startTime, statusMember.getStarted());
+  }
+
+  @Test
+  public void statusRecordsTheStopTime() {
+    //given
+    final LocalDateTime stop = LocalDateTime.of(2017, Month.APRIL, 1, 19, 12);
+    final StoppingData stoppingData = new StoppingData(stop);
+    stoppingData.setDataBus(DataBus.getInstance());
+    final StatusMember statusMember = new StatusMember(1);
+    //when
+    statusMember.accept(stoppingData);
+    //then
+    Assert.assertEquals(stop, statusMember.getStopped());
+  }
+
+  @Test
+  public void statusIgnoresMessageData() {
+    //given
+    final MessageData messageData = new MessageData("message");
+    final StatusMember statusMember = new StatusMember(1);
+    //when
+    statusMember.accept(messageData);
+    //then
+    Assert.assertNull(statusMember.getStarted());
+    Assert.assertNull(statusMember.getStopped());
+  }
+
+}

data-mapper/pom.xml

@@ -28,7 +28,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.14.0</version>
+		<version>1.16.0</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>1.16.0</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>1.16.0</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>1.16.0</version>
   </parent>
   <artifactId>dependency-injection</artifactId>
   <dependencies>

dependency-injection/src/main/java/com/iluwatar/dependency/injection/AdvancedSorceress.java

@@ -0,0 +1,65 @@
+/**
+ * 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.dependency.injection;
+
+/**
+ * The MIT License
+ * Copyright (c) 2014-2017 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.
+ */
+
+
+/**
+ * AdvancedSorceress implements inversion of control. It depends on abstraction that can be injected
+ * through its setter.
+ */
+public class AdvancedSorceress implements Wizard {
+
+  private Tobacco tobacco;
+
+  public void setTobacco(Tobacco tobacco) {
+    this.tobacco = tobacco;
+  }
+
+  @Override
+  public void smoke() {
+    tobacco.smoke(this);
+  }
+}

dependency-injection/src/main/java/com/iluwatar/dependency/injection/App.java

@@ -1,17 +1,17 @@
 /**
  * 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
@@ -26,7 +26,6 @@ import com.google.inject.Guice;
 import com.google.inject.Injector;
 
 /**
- * 
  * Dependency Injection pattern deals with how objects handle their dependencies. The pattern
  * implements so called inversion of control principle. Inversion of control has two specific rules:
  * - High-level modules should not depend on low-level modules. Both should depend on abstractions.
@@ -36,21 +35,21 @@ import com.google.inject.Injector;
  * naive implementation violating the inversion of control principle. It depends directly on a
  * concrete implementation which cannot be changed.
  * <p>
- * The second wizard ({@link AdvancedWizard}) is more flexible. It does not depend on any concrete
- * implementation but abstraction. It utilizes Dependency Injection pattern allowing its
- * {@link Tobacco} dependency to be injected through its constructor. This way, handling the
- * dependency is no longer the wizard's responsibility. It is resolved outside the wizard class.
+ * The second and third wizards({@link AdvancedWizard} and {@link AdvancedSorceress}) are more flexible.
+ * They do not depend on any concrete implementation but abstraction. They utilizes Dependency Injection
+ * pattern allowing their {@link Tobacco} dependency to be injected through constructor ({@link AdvancedWizard})
+ * or setter ({@link AdvancedSorceress}). This way, handling the dependency is no longer the wizard's
+ * responsibility. It is resolved outside the wizard class.
  * <p>
- * The third example takes the pattern a step further. It uses Guice framework for Dependency
+ * The fourth example takes the pattern a step further. It uses Guice framework for Dependency
  * Injection. {@link TobaccoModule} binds a concrete implementation to abstraction. Injector is then
  * used to create {@link GuiceWizard} object with correct dependencies.
- *
  */
 public class App {
 
   /**
    * Program entry point
-   * 
+   *
    * @param args command line args
    */
   public static void main(String[] args) {
@@ -60,6 +59,10 @@ public class App {
     AdvancedWizard advancedWizard = new AdvancedWizard(new SecondBreakfastTobacco());
     advancedWizard.smoke();
 
+    AdvancedSorceress advancedSorceress = new AdvancedSorceress();
+    advancedSorceress.setTobacco(new SecondBreakfastTobacco());
+    advancedSorceress.smoke();
+
     Injector injector = Guice.createInjector(new TobaccoModule());
     GuiceWizard guiceWizard = injector.getInstance(GuiceWizard.class);
     guiceWizard.smoke();

dependency-injection/src/test/java/com/iluwatar/dependency/injection/AdvancedSorceressTest.java

@@ -0,0 +1,76 @@
+/**
+ * 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.dependency.injection;
+
+import com.iluwatar.dependency.injection.utils.InMemoryAppender;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+/**
+ * Date: 28/04/17 - 7:40 AM
+ *
+ * @author Stanislav Kapinus
+ */
+
+public class AdvancedSorceressTest {
+
+  private InMemoryAppender appender;
+
+  @Before
+  public void setUp() {
+    appender = new InMemoryAppender(Tobacco.class);
+  }
+
+  @After
+  public void tearDown() {
+    appender.stop();
+  }
+
+  /**
+   * Test if the {@link AdvancedSorceress} smokes whatever instance of {@link Tobacco} is passed to her
+   * through the setter's parameter
+   */
+  @Test
+  public void testSmokeEveryThing() throws Exception {
+
+    final Tobacco[] tobaccos = {
+        new OldTobyTobacco(), new RivendellTobacco(), new SecondBreakfastTobacco()
+    };
+
+    for (final Tobacco tobacco : tobaccos) {
+      final AdvancedSorceress advancedSorceress = new AdvancedSorceress();
+      advancedSorceress.setTobacco(tobacco);
+      advancedSorceress.smoke();
+      // Verify if the sorceress is smoking the correct tobacco ...
+      assertEquals("AdvancedSorceress smoking " + tobacco.getClass().getSimpleName(), appender.getLastMessage());
+
+    }
+
+    // ... and nothing else is happening.
+    assertEquals(tobaccos.length, appender.getLogSize());
+
+  }
+}

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>1.16.0</version>
   </parent>
   <artifactId>double-checked-locking</artifactId>
   <dependencies>