Updated class diagram PNG

Removed sonar issue and converted Audio to eager singleton for simplicity
1) Test cases were not stopping AudioService before ending test case 2) Changed Audio to be a good singleton, previously because of Audio being bad singleton, test cases which were using static methods could have caused intermittent failures. 3) Made some other refactorings as well
2018-10-21 14:06:08 +05:30 · 2018-10-16 12:55:33 +05:30 · 2018-10-16 12:15:39 +05:30 · 2018-10-13 18:40:10 +03:00 · 2018-10-13 18:28:40 +03:00 · 2018-09-30 21:36:32 +03:00
130 changed files with 194 additions and 220 deletions
--- a/README.md
+++ b/README.md
@ -8,7 +8,6 @@
 [![License MIT](https://img.shields.io/badge/license-MIT-blue.svg)](https://raw.githubusercontent.com/iluwatar/java-design-patterns/master/LICENSE.md)
 [![Join the chat at https://gitter.im/iluwatar/java-design-patterns](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/iluwatar/java-design-patterns?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
 [![Quality Gate](https://sonarcloud.io/api/project_badges/measure?project=com.iluwatar%3Ajava-design-patterns&metric=alert_status)](https://sonarcloud.io/dashboard/index/com.iluwatar%3Ajava-design-patterns)
-[![CII Best Practices](https://bestpractices.coreinfrastructure.org/projects/1503/badge)](https://bestpractices.coreinfrastructure.org/projects/1503)

 # Introduction

--- a/abstract-document/pom.xml
+++ b/abstract-document/pom.xml
@ -29,7 +29,7 @@
    <parent>
        <artifactId>java-design-patterns</artifactId>
        <groupId>com.iluwatar</groupId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
    </parent>
    <artifactId>abstract-document</artifactId>
    <dependencies>
--- a/abstract-factory/pom.xml
+++ b/abstract-factory/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>abstract-factory</artifactId>
  <dependencies>
--- a/acyclic-visitor/pom.xml
+++ b/acyclic-visitor/pom.xml
@ -30,7 +30,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.20.0-SNAPSHOT</version>
+		<version>1.21.0-SNAPSHOT</version>
 	</parent>
 	
 	<artifactId>acyclic-visitor</artifactId>
--- a/adapter/pom.xml
+++ b/adapter/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>adapter</artifactId>
  <dependencies>
--- a/aggregator-microservices/aggregator-service/pom.xml
+++ b/aggregator-microservices/aggregator-service/pom.xml
@ -29,7 +29,7 @@
    <parent>
        <artifactId>aggregator-microservices</artifactId>
        <groupId>com.iluwatar</groupId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

--- a/aggregator-microservices/information-microservice/pom.xml
+++ b/aggregator-microservices/information-microservice/pom.xml
@ -29,7 +29,7 @@
    <parent>
        <artifactId>aggregator-microservices</artifactId>
        <groupId>com.iluwatar</groupId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

--- a/aggregator-microservices/inventory-microservice/pom.xml
+++ b/aggregator-microservices/inventory-microservice/pom.xml
@ -29,7 +29,7 @@
    <parent>
        <artifactId>aggregator-microservices</artifactId>
        <groupId>com.iluwatar</groupId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

--- a/aggregator-microservices/pom.xml
+++ b/aggregator-microservices/pom.xml
@ -29,7 +29,7 @@
    <parent>
        <artifactId>java-design-patterns</artifactId>
        <groupId>com.iluwatar</groupId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>
    <artifactId>aggregator-microservices</artifactId>
--- a/ambassador/pom.xml
+++ b/ambassador/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <artifactId>java-design-patterns</artifactId>
    <groupId>com.iluwatar</groupId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <modelVersion>4.0.0</modelVersion>
  <artifactId>ambassador</artifactId>
--- a/api-gateway/api-gateway-service/pom.xml
+++ b/api-gateway/api-gateway-service/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <artifactId>api-gateway</artifactId>
    <groupId>com.iluwatar</groupId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <modelVersion>4.0.0</modelVersion>
  <artifactId>api-gateway-service</artifactId>
--- a/api-gateway/image-microservice/pom.xml
+++ b/api-gateway/image-microservice/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <artifactId>api-gateway</artifactId>
    <groupId>com.iluwatar</groupId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>

  <modelVersion>4.0.0</modelVersion>
--- a/api-gateway/pom.xml
+++ b/api-gateway/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <artifactId>java-design-patterns</artifactId>
    <groupId>com.iluwatar</groupId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <modelVersion>4.0.0</modelVersion>
  <artifactId>api-gateway</artifactId>
--- a/api-gateway/price-microservice/pom.xml
+++ b/api-gateway/price-microservice/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <artifactId>api-gateway</artifactId>
    <groupId>com.iluwatar</groupId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>

  <modelVersion>4.0.0</modelVersion>
--- a/async-method-invocation/pom.xml
+++ b/async-method-invocation/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>async-method-invocation</artifactId>
  <dependencies>
--- a/balking/pom.xml
+++ b/balking/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <artifactId>java-design-patterns</artifactId>
    <groupId>com.iluwatar</groupId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <modelVersion>4.0.0</modelVersion>

--- a/bridge/pom.xml
+++ b/bridge/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>bridge</artifactId>
  <dependencies>
--- a/builder/pom.xml
+++ b/builder/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>builder</artifactId>
  <dependencies>
--- a/business-delegate/pom.xml
+++ b/business-delegate/pom.xml
@ -30,7 +30,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.20.0-SNAPSHOT</version>
+		<version>1.21.0-SNAPSHOT</version>
 	</parent>
 	<artifactId>business-delegate</artifactId>
 	<dependencies>
--- a/caching/pom.xml
+++ b/caching/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>caching</artifactId>
  <dependencies>
--- a/callback/pom.xml
+++ b/callback/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>callback</artifactId>
  <dependencies>
--- a/chain/pom.xml
+++ b/chain/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>chain</artifactId>
  <dependencies>
--- a/collection-pipeline/pom.xml
+++ b/collection-pipeline/pom.xml
@ -27,7 +27,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>collection-pipeline</artifactId>
  <dependencies>
--- a/command/pom.xml
+++ b/command/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>command</artifactId>
  <dependencies>
--- a/composite/pom.xml
+++ b/composite/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>composite</artifactId>
  <dependencies>
--- a/converter/pom.xml
+++ b/converter/pom.xml
@ -29,7 +29,7 @@
    <parent>
        <artifactId>java-design-patterns</artifactId>
        <groupId>com.iluwatar</groupId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>
    <dependencies>
--- a/cqrs/pom.xml
+++ b/cqrs/pom.xml
@ -21,7 +21,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.20.0-SNAPSHOT</version>
+		<version>1.21.0-SNAPSHOT</version>
 	</parent>
 	<artifactId>cqrs</artifactId>
 	<dependencies>
--- a/dao/pom.xml
+++ b/dao/pom.xml
@ -30,7 +30,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>dao</artifactId>

--- a/data-bus/pom.xml
+++ b/data-bus/pom.xml
@ -33,7 +33,7 @@
    <parent>
        <groupId>com.iluwatar</groupId>
        <artifactId>java-design-patterns</artifactId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
    </parent>
    <artifactId>data-bus</artifactId>
    <dependencies>
--- a/data-mapper/pom.xml
+++ b/data-mapper/pom.xml
@ -28,7 +28,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.20.0-SNAPSHOT</version>
+		<version>1.21.0-SNAPSHOT</version>
 	</parent>
 	<artifactId>data-mapper</artifactId>
 	<dependencies>
--- a/data-transfer-object/pom.xml
+++ b/data-transfer-object/pom.xml
@ -28,7 +28,7 @@
    <parent>
        <groupId>com.iluwatar</groupId>
        <artifactId>java-design-patterns</artifactId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
    </parent>
    <artifactId>data-transfer-object</artifactId>
    <dependencies>
--- a/decorator/pom.xml
+++ b/decorator/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>decorator</artifactId>
  <dependencies>
--- a/delegation/pom.xml
+++ b/delegation/pom.xml
@ -30,7 +30,7 @@
    <parent>
        <artifactId>java-design-patterns</artifactId>
        <groupId>com.iluwatar</groupId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

--- a/dependency-injection/pom.xml
+++ b/dependency-injection/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>dependency-injection</artifactId>
  <dependencies>
--- a/dirty-flag/pom.xml
+++ b/dirty-flag/pom.xml
@ -29,11 +29,11 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <groupId>com.iluwatar</groupId>
  <artifactId>dirty-flag</artifactId>
-  <version>1.20.0-SNAPSHOT</version>
+  <version>1.21.0-SNAPSHOT</version>
  <name>dirty-flag</name>
  <url>http://maven.apache.org</url>
  <properties>
--- a/double-checked-locking/pom.xml
+++ b/double-checked-locking/pom.xml
@ -27,7 +27,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>double-checked-locking</artifactId>
  <dependencies>
--- a/double-dispatch/pom.xml
+++ b/double-dispatch/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>double-dispatch</artifactId>
  <dependencies>
--- a/eip-aggregator/pom.xml
+++ b/eip-aggregator/pom.xml
@ -26,7 +26,7 @@
    <parent>
        <groupId>com.iluwatar</groupId>
        <artifactId>java-design-patterns</artifactId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
    </parent>

    <dependencies>
--- a/eip-message-channel/pom.xml
+++ b/eip-message-channel/pom.xml
@ -30,7 +30,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.20.0-SNAPSHOT</version>
+		<version>1.21.0-SNAPSHOT</version>
 	</parent>
 	<artifactId>eip-message-channel</artifactId>
 	<dependencies>
--- a/eip-publish-subscribe/pom.xml
+++ b/eip-publish-subscribe/pom.xml
@ -28,7 +28,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.20.0-SNAPSHOT</version>
+		<version>1.21.0-SNAPSHOT</version>
 	</parent>
 	<artifactId>eip-publish-subscribe</artifactId>
 	<dependencies>
--- a/eip-splitter/pom.xml
+++ b/eip-splitter/pom.xml
@ -26,7 +26,7 @@
    <parent>
        <groupId>com.iluwatar</groupId>
        <artifactId>java-design-patterns</artifactId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
    </parent>

    <dependencies>
--- a/eip-wire-tap/pom.xml
+++ b/eip-wire-tap/pom.xml
@ -26,7 +26,7 @@
    <parent>
        <groupId>com.iluwatar</groupId>
        <artifactId>java-design-patterns</artifactId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
    </parent>

    <dependencies>
--- a/event-aggregator/pom.xml
+++ b/event-aggregator/pom.xml
@ -28,7 +28,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.20.0-SNAPSHOT</version>
+		<version>1.21.0-SNAPSHOT</version>
 	</parent>
 	<artifactId>event-aggregator</artifactId>
 	<dependencies>
--- a/event-asynchronous/pom.xml
+++ b/event-asynchronous/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>event-asynchronous</artifactId>
  <dependencies>
--- a/event-driven-architecture/pom.xml
+++ b/event-driven-architecture/pom.xml
@ -31,7 +31,7 @@
    <parent>
        <groupId>com.iluwatar</groupId>
        <artifactId>java-design-patterns</artifactId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
    </parent>

    <artifactId>event-driven-architecture</artifactId>
--- a/event-queue/etc/model.png
+++ b/event-queue/etc/model.png
--- a/event-queue/pom.xml
+++ b/event-queue/pom.xml
@ -30,7 +30,7 @@
  <parent>
    <artifactId>java-design-patterns</artifactId>
    <groupId>com.iluwatar</groupId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>event-queue</artifactId>
  <dependencies>
--- a/event-queue/src/main/java/com/iluwatar/event/queue/App.java
+++ b/event-queue/src/main/java/com/iluwatar/event/queue/App.java
@ -47,13 +47,15 @@ public class App {
   * @throws IOException when there is a problem with the audio file loading
   * @throws UnsupportedAudioFileException  when the loaded audio file is unsupported 
   */
-  public static void main(String[] args) throws UnsupportedAudioFileException, IOException {
-    Audio.playSound(Audio.getAudioStream("./etc/Bass-Drum-1.wav"), -10.0f);
-    Audio.playSound(Audio.getAudioStream("./etc/Closed-Hi-Hat-1.wav"), -8.0f);
+  public static void main(String[] args) throws UnsupportedAudioFileException, IOException, InterruptedException {
+    Audio audio = Audio.getInstance();
+    audio.playSound(audio.getAudioStream("./etc/Bass-Drum-1.wav"), -10.0f);
+    audio.playSound(audio.getAudioStream("./etc/Closed-Hi-Hat-1.wav"), -8.0f);
    
    System.out.println("Press Enter key to stop the program...");
-    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
-    br.read();
-    Audio.stopService();
+    try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
+      br.read();
+    }
+    audio.stopService();
  }
 }
--- a/event-queue/src/main/java/com/iluwatar/event/queue/Audio.java
+++ b/event-queue/src/main/java/com/iluwatar/event/queue/Audio.java
@ -23,6 +23,9 @@

 package com.iluwatar.event.queue;

+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import java.io.File;
 import java.io.IOException;

@ -38,49 +41,56 @@ import javax.sound.sampled.UnsupportedAudioFileException;
 *
 */
 public class Audio {
+  private static final Logger LOGGER = LoggerFactory.getLogger(Audio.class);
+  private static final Audio INSTANCE = new Audio();

  private static final int MAX_PENDING = 16;

-  private static int headIndex;
+  private int headIndex;

-  private static int tailIndex;
+  private int tailIndex;

-  private static Thread updateThread = null;
+  private volatile Thread updateThread = null;

-  private static PlayMessage[] pendingAudio = new PlayMessage[MAX_PENDING];
+  private PlayMessage[] pendingAudio = new PlayMessage[MAX_PENDING];
+
+  // Visible only for testing purposes
+  Audio() {
+
+  }
+
+  public static Audio getInstance() {
+    return INSTANCE;
+  }

  /**
-   * This method stops the Update Method's thread. 
+   * This method stops the Update Method's thread and waits till service stops.
   */
-  public static synchronized void stopService() {
+  public synchronized void stopService() throws InterruptedException {
    if (updateThread != null) {
      updateThread.interrupt();
    }
+    updateThread.join();
+    updateThread = null;
  }
  
  /**
   * This method check the Update Method's thread is started.
   * @return boolean
   */
-  public static synchronized boolean isServiceRunning() {
-    if (updateThread != null && updateThread.isAlive() ) {
-      return true;
-    } else {
-      return false;
-    }
+  public synchronized boolean isServiceRunning() {
+    return updateThread != null && updateThread.isAlive();
  }

  /**
   * Starts the thread for the Update Method pattern if it was not started previously.
   * Also when the thread is is ready initializes the indexes of the queue 
   */
-  public static void init() {
+  public void init() {
    if (updateThread == null) {
-      updateThread = new Thread(new Runnable() {
-        public void run() {
-          while (!Thread.currentThread().isInterrupted()) {
-            Audio.update();
-          }
+      updateThread = new Thread(() -> {
+        while (!Thread.currentThread().isInterrupted()) {
+          update();
        }
      });
    }
@ -90,7 +100,7 @@ public class Audio {
  /**
   * This is a synchronized thread starter
   */
-  public static synchronized void startThread() {
+  private synchronized void startThread() {
    if (!updateThread.isAlive()) {
      updateThread.start();
      headIndex = 0;
@ -103,7 +113,7 @@ public class Audio {
   * @param stream is the AudioInputStream for the method
   * @param volume is the level of the audio's volume 
   */
-  public static void playSound(AudioInputStream stream, float volume) {
+  public void playSound(AudioInputStream stream, float volume) {
    init();
    // Walk the pending requests.
    for (int i = headIndex; i != tailIndex; i = (i + 1) % MAX_PENDING) {
@ -123,7 +133,7 @@ public class Audio {
   * This method uses the Update Method pattern.
   * It takes the audio from the queue and plays it
   */
-  public static void update() {
+  private void update() {
    // If there are no pending requests, do nothing.
    if (headIndex == tailIndex) {
      return;
@ -136,13 +146,11 @@ public class Audio {
      clip.open(audioStream);
      clip.start();
    } catch (LineUnavailableException e) {
-      System.err.println("Error occoured while loading the audio: The line is unavailable");
-      e.printStackTrace();
+      LOGGER.trace("Error occoured while loading the audio: The line is unavailable", e);
    } catch (IOException e) {
-      System.err.println("Input/Output error while loading the audio");
-      e.printStackTrace();
+      LOGGER.trace("Input/Output error while loading the audio", e);
    } catch (IllegalArgumentException e) {
-      System.err.println("The system doesn't support the sound: " + e.getMessage());
+      LOGGER.trace("The system doesn't support the sound: " + e.getMessage(), e);
    }
  }

@ -153,7 +161,7 @@ public class Audio {
   * @throws UnsupportedAudioFileException when the audio file is not supported 
   * @throws IOException when the file is not readable
   */
-  public static AudioInputStream getAudioStream(String filePath) 
+  public AudioInputStream getAudioStream(String filePath)
      throws UnsupportedAudioFileException, IOException {
    return AudioSystem.getAudioInputStream(new File(filePath).getAbsoluteFile());
  }
@ -162,7 +170,7 @@ public class Audio {
   * Returns with the message array of the queue 
   * @return PlayMessage[]
   */
-  public static PlayMessage[] getPendingAudio() {
+  public PlayMessage[] getPendingAudio() {
    return pendingAudio;
  }

--- a/event-queue/src/test/java/com/iluwatar/event/queue/AudioTest.java
+++ b/event-queue/src/test/java/com/iluwatar/event/queue/AudioTest.java
@ -23,6 +23,7 @@

 package com.iluwatar.event.queue;

+import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;

 import javax.sound.sampled.UnsupportedAudioFileException;
@ -39,6 +40,12 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
 */
 public class AudioTest {

+  private Audio audio;
+
+  @BeforeEach
+  void createAudioInstance() {
+    audio = new Audio();
+  }
  /**
   * Test here that the playSound method works correctly
   * @throws UnsupportedAudioFileException when the audio file is not supported 
@ -47,13 +54,15 @@ public class AudioTest {
   */
  @Test
  public void testPlaySound() throws UnsupportedAudioFileException, IOException, InterruptedException {
-    Audio.playSound(Audio.getAudioStream("./etc/Bass-Drum-1.wav"), -10.0f);
+    audio.playSound(audio.getAudioStream("./etc/Bass-Drum-1.wav"), -10.0f);
    // test that service is started
-    assertTrue(Audio.isServiceRunning());
+    assertTrue(audio.isServiceRunning());
    // adding a small pause to be sure that the sound is ended
    Thread.sleep(5000);
+
+    audio.stopService();
    // test that service is finished
-    assertFalse(!Audio.isServiceRunning());
+    assertFalse(audio.isServiceRunning());
  }

  /**
@ -64,16 +73,18 @@ public class AudioTest {
   */
  @Test
  public void testQueue() throws UnsupportedAudioFileException, IOException, InterruptedException {
-    Audio.playSound(Audio.getAudioStream("./etc/Bass-Drum-1.aif"), -10.0f);
-    Audio.playSound(Audio.getAudioStream("./etc/Bass-Drum-1.aif"), -10.0f);
-    Audio.playSound(Audio.getAudioStream("./etc/Bass-Drum-1.aif"), -10.0f);
-    assertTrue(Audio.getPendingAudio().length > 0);
+    audio.playSound(audio.getAudioStream("./etc/Bass-Drum-1.aif"), -10.0f);
+    audio.playSound(audio.getAudioStream("./etc/Bass-Drum-1.aif"), -10.0f);
+    audio.playSound(audio.getAudioStream("./etc/Bass-Drum-1.aif"), -10.0f);
+    assertTrue(audio.getPendingAudio().length > 0);
    // test that service is started
-    assertTrue(Audio.isServiceRunning());
+    assertTrue(audio.isServiceRunning());
    // adding a small pause to be sure that the sound is ended
    Thread.sleep(10000);
+
+    audio.stopService();
    // test that service is finished
-    assertFalse(!Audio.isServiceRunning());
+    assertFalse(audio.isServiceRunning());
  }

 }
--- a/event-sourcing/pom.xml
+++ b/event-sourcing/pom.xml
@ -30,7 +30,7 @@
  <parent>
    <artifactId>java-design-patterns</artifactId>
    <groupId>com.iluwatar</groupId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>event-sourcing</artifactId>
  <dependencies>
--- a/execute-around/pom.xml
+++ b/execute-around/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>execute-around</artifactId>
  <dependencies>
--- a/extension-objects/pom.xml
+++ b/extension-objects/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <artifactId>java-design-patterns</artifactId>
    <groupId>com.iluwatar</groupId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <modelVersion>4.0.0</modelVersion>

--- a/facade/pom.xml
+++ b/facade/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>facade</artifactId>
  <dependencies>
--- a/factory-kit/pom.xml
+++ b/factory-kit/pom.xml
@ -30,7 +30,7 @@
    <parent>
        <groupId>com.iluwatar</groupId>
        <artifactId>java-design-patterns</artifactId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
    </parent>
    <artifactId>factory-kit</artifactId>
    <dependencies>
--- a/factory-method/pom.xml
+++ b/factory-method/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>factory-method</artifactId>
  <dependencies>
--- a/feature-toggle/pom.xml
+++ b/feature-toggle/pom.xml
@ -30,7 +30,7 @@
    <parent>
        <artifactId>java-design-patterns</artifactId>
        <groupId>com.iluwatar</groupId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

--- a/fluentinterface/pom.xml
+++ b/fluentinterface/pom.xml
@ -29,7 +29,7 @@
    <parent>
        <artifactId>java-design-patterns</artifactId>
        <groupId>com.iluwatar</groupId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

--- a/flux/pom.xml
+++ b/flux/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>flux</artifactId>
  <dependencies>
--- a/flyweight/pom.xml
+++ b/flyweight/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>flyweight</artifactId>
  <dependencies>
--- a/front-controller/pom.xml
+++ b/front-controller/pom.xml
@ -30,7 +30,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.20.0-SNAPSHOT</version>
+		<version>1.21.0-SNAPSHOT</version>
 	</parent>
 	<artifactId>front-controller</artifactId>
 	<dependencies>
--- a/guarded-suspension/pom.xml
+++ b/guarded-suspension/pom.xml
@ -30,7 +30,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <packaging>jar</packaging>
  <artifactId>guarded-suspension</artifactId>
--- a/half-sync-half-async/pom.xml
+++ b/half-sync-half-async/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>half-sync-half-async</artifactId>
  <dependencies>
--- a/hexagonal/pom.xml
+++ b/hexagonal/pom.xml
@ -30,7 +30,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>hexagonal</artifactId>
  <dependencies>
--- a/hexagonal/src/main/java/com/iluwatar/hexagonal/domain/LotteryNumbers.java
+++ b/hexagonal/src/main/java/com/iluwatar/hexagonal/domain/LotteryNumbers.java
@ -22,13 +22,12 @@
 */
 package com.iluwatar.hexagonal.domain;

-import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashSet;
-import java.util.List;
 import java.util.PrimitiveIterator;
 import java.util.Random;
 import java.util.Set;
+import java.util.Iterator;

 /**
 *
@ -85,11 +84,10 @@ public class LotteryNumbers {
   * @return numbers as comma separated string
   */
  public String getNumbersAsString() {
-    List<Integer> list = new ArrayList<>();
-    list.addAll(numbers);
    StringBuilder builder = new StringBuilder();
+    Iterator<Integer> iterator = numbers.iterator();
    for (int i = 0; i < NUM_NUMBERS; i++) {
-      builder.append(list.get(i));
+      builder.append(iterator.next());
      if (i < NUM_NUMBERS - 1) {
        builder.append(",");
      }
--- a/intercepting-filter/pom.xml
+++ b/intercepting-filter/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>intercepting-filter</artifactId>
  <dependencies>
--- a/interpreter/pom.xml
+++ b/interpreter/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>interpreter</artifactId>
  <dependencies>
--- a/iterator/pom.xml
+++ b/iterator/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>iterator</artifactId>
  <dependencies>
--- a/layers/pom.xml
+++ b/layers/pom.xml
@ -30,7 +30,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.20.0-SNAPSHOT</version>
+		<version>1.21.0-SNAPSHOT</version>
 	</parent>
 	<groupId>com.iluwatar.layers</groupId>
 	<artifactId>layers</artifactId>
--- a/lazy-loading/pom.xml
+++ b/lazy-loading/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>lazy-loading</artifactId>
  <dependencies>
--- a/marker/pom.xml
+++ b/marker/pom.xml
@ -24,7 +24,7 @@
  <parent>
    <artifactId>java-design-patterns</artifactId>
    <groupId>com.iluwatar</groupId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <modelVersion>4.0.0</modelVersion>

--- a/mediator/pom.xml
+++ b/mediator/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>mediator</artifactId>
  <dependencies>
--- a/memento/pom.xml
+++ b/memento/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>memento</artifactId>
  <dependencies>
--- a/model-view-controller/pom.xml
+++ b/model-view-controller/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>model-view-controller</artifactId>
  <dependencies>
--- a/model-view-presenter/pom.xml
+++ b/model-view-presenter/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>model-view-presenter</artifactId>
  <name>model-view-presenter</name>
--- a/module/.gitignore
+++ b/module/.gitignore
@ -0,0 +1,2 @@
+error.txt
+output.txt
--- a/module/error.txt
+++ b/module/error.txt
@ -1,23 +0,0 @@
-====
-    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.
-====
-
--- a/module/output.txt
+++ b/module/output.txt
@ -1,23 +0,0 @@
-====
-    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.
-====
-
--- a/module/pom.xml
+++ b/module/pom.xml
@ -28,7 +28,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.20.0-SNAPSHOT</version>
+		<version>1.21.0-SNAPSHOT</version>
 	</parent>
 	<artifactId>module</artifactId>
 	<dependencies>
--- a/monad/pom.xml
+++ b/monad/pom.xml
@ -29,7 +29,7 @@
    <parent>
        <groupId>com.iluwatar</groupId>
        <artifactId>java-design-patterns</artifactId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
    </parent>
    <artifactId>monad</artifactId>
    <dependencies>
--- a/monostate/pom.xml
+++ b/monostate/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>monostate</artifactId>
  <dependencies>
--- a/multiton/pom.xml
+++ b/multiton/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>multiton</artifactId>
  <dependencies>
--- a/mute-idiom/pom.xml
+++ b/mute-idiom/pom.xml
@ -21,7 +21,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.20.0-SNAPSHOT</version>
+		<version>1.21.0-SNAPSHOT</version>
 	</parent>
 	<artifactId>mute-idiom</artifactId>
 	<dependencies>
--- a/mutex/pom.xml
+++ b/mutex/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>mutex</artifactId>
  <dependencies>
--- a/naked-objects/dom/pom.xml
+++ b/naked-objects/dom/pom.xml
@ -16,7 +16,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>naked-objects</artifactId>
-		<version>1.20.0-SNAPSHOT</version>
+		<version>1.21.0-SNAPSHOT</version>
 	</parent>

 	<artifactId>naked-objects-dom</artifactId>
--- a/naked-objects/fixture/pom.xml
+++ b/naked-objects/fixture/pom.xml
@ -16,7 +16,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>naked-objects</artifactId>
-		<version>1.20.0-SNAPSHOT</version>
+		<version>1.21.0-SNAPSHOT</version>
 	</parent>

 	<artifactId>naked-objects-fixture</artifactId>
--- a/naked-objects/integtests/pom.xml
+++ b/naked-objects/integtests/pom.xml
@ -16,7 +16,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>naked-objects</artifactId>
-		<version>1.20.0-SNAPSHOT</version>
+		<version>1.21.0-SNAPSHOT</version>
 	</parent>

 	<artifactId>naked-objects-integtests</artifactId>
--- a/naked-objects/pom.xml
+++ b/naked-objects/pom.xml
@ -15,7 +15,7 @@
 	<parent>
 		<artifactId>java-design-patterns</artifactId>
 		<groupId>com.iluwatar</groupId>
-		<version>1.20.0-SNAPSHOT</version>
+		<version>1.21.0-SNAPSHOT</version>
 	</parent>

 	<artifactId>naked-objects</artifactId>
@ -350,17 +350,17 @@
 			<dependency>
 				<groupId>${project.groupId}</groupId>
 				<artifactId>naked-objects-dom</artifactId>
-				<version>1.20.0-SNAPSHOT</version>
+				<version>1.21.0-SNAPSHOT</version>
 			</dependency>
 			<dependency>
 				<groupId>${project.groupId}</groupId>
 				<artifactId>naked-objects-fixture</artifactId>
-				<version>1.20.0-SNAPSHOT</version>
+				<version>1.21.0-SNAPSHOT</version>
 			</dependency>
 			<dependency>
 				<groupId>${project.groupId}</groupId>
 				<artifactId>naked-objects-webapp</artifactId>
-				<version>1.20.0-SNAPSHOT</version>
+				<version>1.21.0-SNAPSHOT</version>
 			</dependency>

 		</dependencies>
--- a/naked-objects/webapp/pom.xml
+++ b/naked-objects/webapp/pom.xml
@ -16,7 +16,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>naked-objects</artifactId>
-		<version>1.20.0-SNAPSHOT</version>
+		<version>1.21.0-SNAPSHOT</version>
 	</parent>

 	<artifactId>naked-objects-webapp</artifactId>
--- a/null-object/pom.xml
+++ b/null-object/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>null-object</artifactId>
  <dependencies>
--- a/object-mother/pom.xml
+++ b/object-mother/pom.xml
@ -30,7 +30,7 @@
    <parent>
        <groupId>com.iluwatar</groupId>
        <artifactId>java-design-patterns</artifactId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
    </parent>
    <artifactId>object-mother</artifactId>
    <dependencies>
--- a/object-pool/pom.xml
+++ b/object-pool/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>object-pool</artifactId>
  <dependencies>
--- a/observer/pom.xml
+++ b/observer/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>observer</artifactId>
  <dependencies>
--- a/page-object/pom.xml
+++ b/page-object/pom.xml
@ -29,7 +29,7 @@
    <parent>
        <groupId>com.iluwatar</groupId>
        <artifactId>java-design-patterns</artifactId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
    </parent>
    <artifactId>page-object</artifactId>
    <dependencies>
--- a/partial-response/pom.xml
+++ b/partial-response/pom.xml
@ -29,7 +29,7 @@
    <parent>
        <artifactId>java-design-patterns</artifactId>
        <groupId>com.iluwatar</groupId>
-        <version>1.20.0-SNAPSHOT</version>
+        <version>1.21.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

--- a/poison-pill/pom.xml
+++ b/poison-pill/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>poison-pill</artifactId>
  <dependencies>
--- a/pom.xml
+++ b/pom.xml
@ -21,7 +21,7 @@
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
    <packaging>pom</packaging>
    <inceptionYear>2014</inceptionYear>
    <properties>
--- a/private-class-data/pom.xml
+++ b/private-class-data/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>private-class-data</artifactId>
  <dependencies>
--- a/producer-consumer/pom.xml
+++ b/producer-consumer/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>producer-consumer</artifactId>
  <dependencies>
--- a/promise/pom.xml
+++ b/promise/pom.xml
@ -29,7 +29,7 @@
  <parent>
    <groupId>com.iluwatar</groupId>
    <artifactId>java-design-patterns</artifactId>
-    <version>1.20.0-SNAPSHOT</version>
+    <version>1.21.0-SNAPSHOT</version>
  </parent>
  <artifactId>promise</artifactId>
  <dependencies>
--- a/Show More
+++ b/Show More
Author	SHA1	Message	Date
npathai	5a56b922e4	Updated class diagram PNG	2018-10-21 14:06:08 +05:30
Narendra Pathai	c0da4b3165	Removed sonar issue and converted Audio to eager singleton for simplicity	2018-10-16 12:55:33 +05:30
Narendra Pathai	9bbb4da3d5	1) Test cases were not stopping AudioService before ending test case 2) Changed Audio to be a good singleton, previously because of Audio being bad singleton, test cases which were using static methods could have caused intermittent failures. 3) Made some other refactorings as well	2018-10-16 12:15:39 +05:30
Ilkka Seppälä	db33cc533b	Remove CII best practices badge	2018-10-13 18:40:10 +03:00
Ilkka Seppälä	8433c7b712	Merge pull request #793 from andrievsky/master Fix redundant list alloc in LotteryNumbers	2018-10-13 18:28:40 +03:00
Ilkka Seppälä	ee74fec53c	Fix pattern title	2018-09-30 21:36:32 +03:00
Ilkka Seppälä	7a7e891384	Set version for next development iteration	2018-09-30 21:05:57 +03:00
Ilkka Seppälä	26d6d96f78	Reach milestone 1.20.0	2018-09-30 21:03:48 +03:00
Ilkka Seppälä	3cec7a9ec1	Merge pull request #796 from LyndonArmitage/module-ignore-test-output Delete & Ignore output.txt & error.txt	2018-09-25 22:49:25 +03:00
Ilkka Seppälä	b079aec1fd	Merge pull request #794 from iluwatar/Issue781 #781 Resolved ClasscastException from Acyclic Visitor	2018-09-25 22:45:25 +03:00
Lyndon Armitage	8f53df91b9	Delete & Ignore output.txt & error.txt Both output.txt and error.txt are produced by tests. Each file contained a header that was overridden upon executing said tests causing tracked files to be changed. Added them to a local .gitignore file for this module.	2018-09-24 10:08:02 +01:00
Nick Andrievsky	1d12d94bac	Fix redundant list alloc in LotteryNumbers	2018-09-11 11:55:53 +02:00