docs: update .all-contributorsrc [skip ci]

#1313 Add Separated Interface pattern

.all-contributorsrc

@@ -1082,7 +1082,8 @@
       "avatar_url": "https://avatars1.githubusercontent.com/u/10645273?v=4",
       "profile": "https://github.com/ravening",
       "contributions": [
-        "code"
+        "code",
+        "review"
       ]
     },
     {
@@ -1176,6 +1177,42 @@
       "contributions": [
         "code"
       ]
+    },
+    {
+      "login": "fedorskvorcov",
+      "name": "Fedor Skvorcov",
+      "avatar_url": "https://avatars3.githubusercontent.com/u/43882212?v=4",
+      "profile": "https://github.com/fedorskvorcov",
+      "contributions": [
+        "code"
+      ]
+    },
+    {
+      "login": "samilAyoub",
+      "name": "samilAyoub",
+      "avatar_url": "https://avatars0.githubusercontent.com/u/61546990?v=4",
+      "profile": "https://github.com/samilAyoub",
+      "contributions": [
+        "code"
+      ]
+    },
+    {
+      "login": "vdlald",
+      "name": "Vladislav Golubinov",
+      "avatar_url": "https://avatars0.githubusercontent.com/u/29997701?v=4",
+      "profile": "https://github.com/vdlald",
+      "contributions": [
+        "code"
+      ]
+    },
+    {
+      "login": "swarajsaaj",
+      "name": "Swaraj",
+      "avatar_url": "https://avatars2.githubusercontent.com/u/6285049?v=4",
+      "profile": "https://github.com/swarajsaaj",
+      "contributions": [
+        "code"
+      ]
     }
   ],
   "contributorsPerLine": 4,

.github/workflows/maven-ci.yml

@@ -33,10 +33,13 @@ on:
 jobs:
   build:
 
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-20.04
 
     steps:
     - uses: actions/checkout@v2
+      with:
+        # Disabling shallow clone for improving relevancy of SonarQube reporting
+        fetch-depth: 0
     - name: Set up JDK 11
       uses: actions/setup-java@v1
       with:
@@ -49,14 +52,11 @@ jobs:
           ${{ runner.os }}-maven-
     # Some tests need screen access
     - name: Install xvfb
-      run: sudo apt-get install xvfb
-    # SonarQube scan does not work for forked repositories
+      run: sudo apt-get install -y xvfb
+    # The SonarQube analysis is only for the master branch of the main repository.
+    # SonarQube scan does not work for forked repositories try changing it to xvfb-run mvn clean verify
     # See https://jira.sonarsource.com/browse/MMF-1371
-    - name: Build with Maven
-      if: github.ref != 'refs/heads/master'
-      run: xvfb-run mvn clean verify
     - name: Build with Maven and run SonarQube analysis
-      if: github.ref == 'refs/heads/master'
       run: xvfb-run mvn clean verify org.sonarsource.scanner.maven:sonar-maven-plugin:sonar
       env:
         # These two env variables are needed for sonar analysis

.github/workflows/maven-pr-builder.yml

@@ -33,7 +33,7 @@ on:
 jobs:
   build:
 
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-20.04
 
     steps:
     - uses: actions/checkout@v2
@@ -49,9 +49,9 @@ jobs:
           ${{ runner.os }}-maven-
     # Some tests need screen access
     - name: Install xvfb
-      run: sudo apt-get install xvfb
-    # SonarQube scan does not work for forked repositories
+      run: sudo apt-get install -y xvfb
+    # This worflow is only for building Pull Requests, the master branch runs Sonar analysis on the main repository.
+    # SonarQube scan does not work for forked repositories.
     # See https://jira.sonarsource.com/browse/MMF-1371
     - name: Build with Maven
-      if: github.ref != 'refs/heads/master'
       run: xvfb-run mvn clean verify

README.md

@@ -10,7 +10,7 @@
 [![Coverage](https://sonarcloud.io/api/project_badges/measure?project=iluwatar_java-design-patterns&metric=coverage)](https://sonarcloud.io/dashboard?id=iluwatar_java-design-patterns)
 [![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)
 <!-- ALL-CONTRIBUTORS-BADGE:START - Do not remove or modify this section -->
-[![All Contributors](https://img.shields.io/badge/all_contributors-129-orange.svg?style=flat-square)](#contributors-)
+[![All Contributors](https://img.shields.io/badge/all_contributors-133-orange.svg?style=flat-square)](#contributors-)
 <!-- ALL-CONTRIBUTORS-BADGE:END -->
 
 # Introduction
@@ -246,7 +246,7 @@ This project is licensed under the terms of the MIT license.
   <tr>
     <td align="center"><a href="https://github.com/nishant"><img src="https://avatars2.githubusercontent.com/u/15331971?v=4" width="100px;" alt=""/><br /><sub><b>Nishant Arora</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=nishant" title="Code">💻</a></td>
     <td align="center"><a href="https://github.com/raja-peeyush-kumar-singh"><img src="https://avatars0.githubusercontent.com/u/5496024?v=4" width="100px;" alt=""/><br /><sub><b>Peeyush</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=raja-peeyush-kumar-singh" title="Code">💻</a></td>
-    <td align="center"><a href="https://github.com/ravening"><img src="https://avatars1.githubusercontent.com/u/10645273?v=4" width="100px;" alt=""/><br /><sub><b>Rakesh</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ravening" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/ravening"><img src="https://avatars1.githubusercontent.com/u/10645273?v=4" width="100px;" alt=""/><br /><sub><b>Rakesh</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ravening" title="Code">💻</a> <a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3Aravening" title="Reviewed Pull Requests">👀</a></td>
     <td align="center"><a href="https://github.com/vINCENT8888801"><img src="https://avatars0.githubusercontent.com/u/8037883?v=4" width="100px;" alt=""/><br /><sub><b>Wei Seng</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=vINCENT8888801" title="Code">💻</a></td>
   </tr>
   <tr>
@@ -263,6 +263,12 @@ This project is licensed under the terms of the MIT license.
   </tr>
   <tr>
     <td align="center"><a href="https://www.stefan-birkner.de"><img src="https://avatars1.githubusercontent.com/u/711349?v=4" width="100px;" alt=""/><br /><sub><b>Stefan Birkner</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=stefanbirkner" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/fedorskvorcov"><img src="https://avatars3.githubusercontent.com/u/43882212?v=4" width="100px;" alt=""/><br /><sub><b>Fedor Skvorcov</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=fedorskvorcov" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/samilAyoub"><img src="https://avatars0.githubusercontent.com/u/61546990?v=4" width="100px;" alt=""/><br /><sub><b>samilAyoub</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=samilAyoub" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/vdlald"><img src="https://avatars0.githubusercontent.com/u/29997701?v=4" width="100px;" alt=""/><br /><sub><b>Vladislav Golubinov</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=vdlald" title="Code">💻</a></td>
+  </tr>
+  <tr>
+    <td align="center"><a href="https://github.com/swarajsaaj"><img src="https://avatars2.githubusercontent.com/u/6285049?v=4" width="100px;" alt=""/><br /><sub><b>Swaraj</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=swarajsaaj" title="Code">💻</a></td>
   </tr>
 </table>
 

abstract-document/pom.xml

@@ -21,7 +21,7 @@
 	<parent>
 		<artifactId>java-design-patterns</artifactId>
 		<groupId>com.iluwatar</groupId>
-		<version>1.23.0-SNAPSHOT</version>
+		<version>1.24.0-SNAPSHOT</version>
 	</parent>
 	<artifactId>abstract-document</artifactId>
 	<dependencies>

abstract-factory/pom.xml

@@ -22,7 +22,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.23.0-SNAPSHOT</version>
+		<version>1.24.0-SNAPSHOT</version>
 	</parent>
 	<artifactId>abstract-factory</artifactId>
 	<dependencies>

abstract-factory/src/main/java/com/iluwatar/abstractfactory/App.java

@@ -23,7 +23,6 @@
 
 package com.iluwatar.abstractfactory;
 
-import com.iluwatar.abstractfactory.App.FactoryMaker.KingdomType;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -41,84 +40,14 @@ import org.slf4j.LoggerFactory;
  * and its implementations ( {@link ElfKingdomFactory}, {@link OrcKingdomFactory}). The example uses
  * both concrete implementations to create a king, a castle and an army.
  */
-public class App {
+public class App implements Runnable {
 
-  private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
+  private static Logger log = LoggerFactory.getLogger(App.class);
 
-  private King king;
-  private Castle castle;
-  private Army army;
+  private final Kingdom kingdom = new Kingdom();
 
-  /**
-   * Creates kingdom.
-   */
-  public void createKingdom(final KingdomFactory factory) {
-    setKing(factory.createKing());
-    setCastle(factory.createCastle());
-    setArmy(factory.createArmy());
-  }
-
-  King getKing(final KingdomFactory factory) {
-    return factory.createKing();
-  }
-
-  public King getKing() {
-    return king;
-  }
-
-  private void setKing(final King king) {
-    this.king = king;
-  }
-
-  Castle getCastle(final KingdomFactory factory) {
-    return factory.createCastle();
-  }
-
-  public Castle getCastle() {
-    return castle;
-  }
-
-  private void setCastle(final Castle castle) {
-    this.castle = castle;
-  }
-
-  Army getArmy(final KingdomFactory factory) {
-    return factory.createArmy();
-  }
-
-  public Army getArmy() {
-    return army;
-  }
-
-  private void setArmy(final Army army) {
-    this.army = army;
-  }
-
-  /**
-   * The factory of kingdom factories.
-   */
-  public static class FactoryMaker {
-
-    /**
-     * Enumeration for the different types of Kingdoms.
-     */
-    public enum KingdomType {
-      ELF, ORC
-    }
-
-    /**
-     * The factory method to create KingdomFactory concrete objects.
-     */
-    public static KingdomFactory makeFactory(KingdomType type) {
-      switch (type) {
-        case ELF:
-          return new ElfKingdomFactory();
-        case ORC:
-          return new OrcKingdomFactory();
-        default:
-          throw new IllegalArgumentException("KingdomType not supported.");
-      }
-    }
+  public Kingdom getKingdom() {
+    return kingdom;
   }
 
   /**
@@ -127,19 +56,33 @@ public class App {
    * @param args command line args
    */
   public static void main(String[] args) {
-
     var app = new App();
+    app.run();
+  }
 
-    LOGGER.info("Elf Kingdom");
-    app.createKingdom(FactoryMaker.makeFactory(KingdomType.ELF));
-    LOGGER.info(app.getArmy().getDescription());
-    LOGGER.info(app.getCastle().getDescription());
-    LOGGER.info(app.getKing().getDescription());
+  @Override
+  public void run() {
+    log.info("Elf Kingdom");
+    createKingdom(Kingdom.FactoryMaker.KingdomType.ELF);
+    log.info(kingdom.getArmy().getDescription());
+    log.info(kingdom.getCastle().getDescription());
+    log.info(kingdom.getKing().getDescription());
 
-    LOGGER.info("Orc Kingdom");
-    app.createKingdom(FactoryMaker.makeFactory(KingdomType.ORC));
-    LOGGER.info(app.getArmy().getDescription());
-    LOGGER.info(app.getCastle().getDescription());
-    LOGGER.info(app.getKing().getDescription());
+    log.info("Orc Kingdom");
+    createKingdom(Kingdom.FactoryMaker.KingdomType.ORC);
+    log.info(kingdom.getArmy().getDescription());
+    log.info(kingdom.getCastle().getDescription());
+    log.info(kingdom.getKing().getDescription());
+  }
+
+  /**
+   * Creates kingdom.
+   * @param kingdomType type of Kingdom
+   */
+  public void createKingdom(final Kingdom.FactoryMaker.KingdomType kingdomType) {
+    final KingdomFactory kingdomFactory = Kingdom.FactoryMaker.makeFactory(kingdomType);
+    kingdom.setKing(kingdomFactory.createKing());
+    kingdom.setCastle(kingdomFactory.createCastle());
+    kingdom.setArmy(kingdomFactory.createArmy());
   }
 }

abstract-factory/src/main/java/com/iluwatar/abstractfactory/Kingdom.java

@@ -0,0 +1,59 @@
+package com.iluwatar.abstractfactory;
+
+public class Kingdom {
+
+  private King king;
+  private Castle castle;
+  private Army army;
+
+  public King getKing() {
+    return king;
+  }
+
+  public Castle getCastle() {
+    return castle;
+  }
+
+  public Army getArmy() {
+    return army;
+  }
+
+  public void setKing(King king) {
+    this.king = king;
+  }
+
+  public void setCastle(Castle castle) {
+    this.castle = castle;
+  }
+
+  public void setArmy(Army army) {
+    this.army = army;
+  }
+
+  /**
+   * The factory of kingdom factories.
+   */
+  public static class FactoryMaker {
+
+    /**
+     * Enumeration for the different types of Kingdoms.
+     */
+    public enum KingdomType {
+      ELF, ORC
+    }
+
+    /**
+     * The factory method to create KingdomFactory concrete objects.
+     */
+    public static KingdomFactory makeFactory(KingdomType type) {
+      switch (type) {
+        case ELF:
+          return new ElfKingdomFactory();
+        case ORC:
+          return new OrcKingdomFactory();
+        default:
+          throw new IllegalArgumentException("KingdomType not supported.");
+      }
+    }
+  }
+}

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

@@ -23,65 +23,71 @@
 
 package com.iluwatar.abstractfactory;
 
+import org.junit.jupiter.api.Test;
+
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
-import com.iluwatar.abstractfactory.App.FactoryMaker;
-import com.iluwatar.abstractfactory.App.FactoryMaker.KingdomType;
-import org.junit.jupiter.api.BeforeEach;
-import org.junit.jupiter.api.Test;
-
 /**
  * Test for abstract factory.
  */
 public class AbstractFactoryTest {
 
   private final App app = new App();
-  private KingdomFactory elfFactory;
-  private KingdomFactory orcFactory;
-
-  @BeforeEach
-  public void setUp() {
-    elfFactory = FactoryMaker.makeFactory(KingdomType.ELF);
-    orcFactory = FactoryMaker.makeFactory(KingdomType.ORC);
-  }
 
   @Test
   public void king() {
-    final var elfKing = app.getKing(elfFactory);
+    app.createKingdom(Kingdom.FactoryMaker.KingdomType.ELF);
+    final var kingdom = app.getKingdom();
+
+    final var elfKing = kingdom.getKing();
     assertTrue(elfKing instanceof ElfKing);
     assertEquals(ElfKing.DESCRIPTION, elfKing.getDescription());
-    final var orcKing = app.getKing(orcFactory);
+
+    app.createKingdom(Kingdom.FactoryMaker.KingdomType.ORC);
+    final var orcKing = kingdom.getKing();
     assertTrue(orcKing instanceof OrcKing);
     assertEquals(OrcKing.DESCRIPTION, orcKing.getDescription());
   }
 
   @Test
   public void castle() {
-    final var elfCastle = app.getCastle(elfFactory);
+    app.createKingdom(Kingdom.FactoryMaker.KingdomType.ELF);
+    final var kingdom = app.getKingdom();
+
+    final var elfCastle = kingdom.getCastle();
     assertTrue(elfCastle instanceof ElfCastle);
     assertEquals(ElfCastle.DESCRIPTION, elfCastle.getDescription());
-    final var orcCastle = app.getCastle(orcFactory);
+
+    app.createKingdom(Kingdom.FactoryMaker.KingdomType.ORC);
+    final var orcCastle = kingdom.getCastle();
     assertTrue(orcCastle instanceof OrcCastle);
     assertEquals(OrcCastle.DESCRIPTION, orcCastle.getDescription());
   }
 
   @Test
   public void army() {
-    final var elfArmy = app.getArmy(elfFactory);
+    app.createKingdom(Kingdom.FactoryMaker.KingdomType.ELF);
+    final var kingdom = app.getKingdom();
+
+    final var elfArmy = kingdom.getArmy();
     assertTrue(elfArmy instanceof ElfArmy);
     assertEquals(ElfArmy.DESCRIPTION, elfArmy.getDescription());
-    final var orcArmy = app.getArmy(orcFactory);
+
+    app.createKingdom(Kingdom.FactoryMaker.KingdomType.ORC);
+    final var orcArmy = kingdom.getArmy();
     assertTrue(orcArmy instanceof OrcArmy);
     assertEquals(OrcArmy.DESCRIPTION, orcArmy.getDescription());
   }
 
   @Test
   public void createElfKingdom() {
-    app.createKingdom(elfFactory);
-    final var king = app.getKing();
-    final var castle = app.getCastle();
-    final var army = app.getArmy();
+    app.createKingdom(Kingdom.FactoryMaker.KingdomType.ELF);
+    final var kingdom = app.getKingdom();
+
+    final var king = kingdom.getKing();
+    final var castle = kingdom.getCastle();
+    final var army = kingdom.getArmy();
     assertTrue(king instanceof ElfKing);
     assertEquals(ElfKing.DESCRIPTION, king.getDescription());
     assertTrue(castle instanceof ElfCastle);
@@ -92,10 +98,12 @@ public class AbstractFactoryTest {
 
   @Test
   public void createOrcKingdom() {
-    app.createKingdom(orcFactory);
-    final var king = app.getKing();
-    final var castle = app.getCastle();
-    final var army = app.getArmy();
+    app.createKingdom(Kingdom.FactoryMaker.KingdomType.ORC);
+    final var kingdom = app.getKingdom();
+
+    final var king = kingdom.getKing();
+    final var castle = kingdom.getCastle();
+    final var army = kingdom.getArmy();
     assertTrue(king instanceof OrcKing);
     assertEquals(OrcKing.DESCRIPTION, king.getDescription());
     assertTrue(castle instanceof OrcCastle);

acyclic-visitor/pom.xml

@@ -21,7 +21,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.23.0-SNAPSHOT</version>
+		<version>1.24.0-SNAPSHOT</version>
 	</parent>
 
 	<artifactId>acyclic-visitor</artifactId>

adapter/pom.xml

@@ -22,7 +22,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.23.0-SNAPSHOT</version>
+		<version>1.24.0-SNAPSHOT</version>
 	</parent>
 	<artifactId>adapter</artifactId>
 	<dependencies>

aggregator-microservices/aggregator-service/pom.xml

@@ -20,7 +20,7 @@
 	<parent>
 		<artifactId>aggregator-microservices</artifactId>
 		<groupId>com.iluwatar</groupId>
-		<version>1.23.0-SNAPSHOT</version>
+		<version>1.24.0-SNAPSHOT</version>
 	</parent>
 	<modelVersion>4.0.0</modelVersion>
 	<artifactId>aggregator-service</artifactId>

aggregator-microservices/information-microservice/pom.xml

@@ -20,7 +20,7 @@
 	<parent>
 		<artifactId>aggregator-microservices</artifactId>
 		<groupId>com.iluwatar</groupId>
-		<version>1.23.0-SNAPSHOT</version>
+		<version>1.24.0-SNAPSHOT</version>
 	</parent>
 	<modelVersion>4.0.0</modelVersion>
 

aggregator-microservices/inventory-microservice/pom.xml

@@ -20,7 +20,7 @@
 	<parent>
 		<artifactId>aggregator-microservices</artifactId>
 		<groupId>com.iluwatar</groupId>
-		<version>1.23.0-SNAPSHOT</version>
+		<version>1.24.0-SNAPSHOT</version>
 	</parent>
 	<modelVersion>4.0.0</modelVersion>
 	<artifactId>inventory-microservice</artifactId>

aggregator-microservices/pom.xml

@@ -29,7 +29,7 @@
     <parent>
         <artifactId>java-design-patterns</artifactId>
         <groupId>com.iluwatar</groupId>
-        <version>1.23.0-SNAPSHOT</version>
+        <version>1.24.0-SNAPSHOT</version>
     </parent>
     <modelVersion>4.0.0</modelVersion>
     <artifactId>aggregator-microservices</artifactId>

ambassador/pom.xml

@@ -20,7 +20,7 @@
 	<parent>
 		<artifactId>java-design-patterns</artifactId>
 		<groupId>com.iluwatar</groupId>
-		<version>1.23.0-SNAPSHOT</version>
+		<version>1.24.0-SNAPSHOT</version>
 	</parent>
 	<modelVersion>4.0.0</modelVersion>
 	<artifactId>ambassador</artifactId>

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

@@ -29,7 +29,7 @@
   <parent>
     <artifactId>api-gateway</artifactId>
     <groupId>com.iluwatar</groupId>
-    <version>1.23.0-SNAPSHOT</version>
+    <version>1.24.0-SNAPSHOT</version>
   </parent>
   <modelVersion>4.0.0</modelVersion>
   <artifactId>api-gateway-service</artifactId>

api-gateway/image-microservice/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <artifactId>api-gateway</artifactId>
     <groupId>com.iluwatar</groupId>
-    <version>1.23.0-SNAPSHOT</version>
+    <version>1.24.0-SNAPSHOT</version>
   </parent>
   <modelVersion>4.0.0</modelVersion>
   <artifactId>image-microservice</artifactId>

api-gateway/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <artifactId>java-design-patterns</artifactId>
     <groupId>com.iluwatar</groupId>
-    <version>1.23.0-SNAPSHOT</version>
+    <version>1.24.0-SNAPSHOT</version>
   </parent>
   <modelVersion>4.0.0</modelVersion>
   <artifactId>api-gateway</artifactId>

api-gateway/price-microservice/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <artifactId>api-gateway</artifactId>
     <groupId>com.iluwatar</groupId>
-    <version>1.23.0-SNAPSHOT</version>
+    <version>1.24.0-SNAPSHOT</version>
   </parent>
 
   <modelVersion>4.0.0</modelVersion>

arrange-act-assert/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <artifactId>java-design-patterns</artifactId>
     <groupId>com.iluwatar</groupId>
-    <version>1.23.0-SNAPSHOT</version>
+    <version>1.24.0-SNAPSHOT</version>
   </parent>
   <modelVersion>4.0.0</modelVersion>
 

async-method-invocation/pom.xml

@@ -22,7 +22,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.23.0-SNAPSHOT</version>
+		<version>1.24.0-SNAPSHOT</version>
 	</parent>
 	<artifactId>async-method-invocation</artifactId>
 	<dependencies>

balking/pom.xml

@@ -20,7 +20,7 @@
 	<parent>
 		<artifactId>java-design-patterns</artifactId>
 		<groupId>com.iluwatar</groupId>
-		<version>1.23.0-SNAPSHOT</version>
+		<version>1.24.0-SNAPSHOT</version>
 	</parent>
 	<modelVersion>4.0.0</modelVersion>
 

bridge/pom.xml

@@ -22,7 +22,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.23.0-SNAPSHOT</version>
+		<version>1.24.0-SNAPSHOT</version>
 	</parent>
 	<artifactId>bridge</artifactId>
 	<dependencies>

builder/README.md

@@ -9,36 +9,47 @@ tags:
 ---
 
 ## Intent
-Separate the construction of a complex object from its
-representation so that the same construction process can create different
-representations.
+
+Separate the construction of a complex object from its representation so that the same construction 
+process can create different representations.
 
 ## Explanation
 
 Real world example
 
-> Imagine a character generator for a role playing game. The easiest option is to let computer create the character for you. But if you want to select the character details like profession, gender, hair color etc. the character generation becomes a step-by-step process that completes when all the selections are ready.
+> Imagine a character generator for a role-playing game. The easiest option is to let the computer 
+> create the character for you. If you want to manually select the character details like 
+> profession, gender, hair color etc. the character generation becomes a step-by-step process that 
+> completes when all the selections are ready.
 
 In plain words
 
-> Allows you to create different flavors of an object while avoiding constructor pollution. Useful when there could be several flavors of an object. Or when there are a lot of steps involved in creation of an object.
+> Allows you to create different flavors of an object while avoiding constructor pollution. Useful 
+> when there could be several flavors of an object. Or when there are a lot of steps involved in 
+> creation of an object.
 
 Wikipedia says
 
-> The builder pattern is an object creation software design pattern with the intentions of finding a solution to the telescoping constructor anti-pattern.
+> The builder pattern is an object creation software design pattern with the intentions of finding 
+> a solution to the telescoping constructor anti-pattern.
 
-Having said that let me add a bit about what telescoping constructor anti-pattern is. At one point or the other we have all seen a constructor like below:
+Having said that let me add a bit about what telescoping constructor anti-pattern is. At one point 
+or the other, we have all seen a constructor like below:
 
 ```java
 public Hero(Profession profession, String name, HairType hairType, HairColor hairColor, Armor armor, Weapon weapon) {
 }
 ```
 
-As you can see the number of constructor parameters can quickly get out of hand and it might become difficult to understand the arrangement of parameters. Plus this parameter list could keep on growing if you would want to add more options in future. This is called telescoping constructor anti-pattern.
+As you can see the number of constructor parameters can quickly get out of hand, and it may become 
+difficult to understand the arrangement of parameters. Plus this parameter list could keep on 
+growing if you would want to add more options in the future. This is called telescoping constructor 
+anti-pattern.
 
 **Programmatic Example**
 
-The sane alternative is to use the Builder pattern. First of all we have our hero that we want to create
+The sane alternative is to use the Builder pattern. First of all we have our hero that we want to 
+create:
 
 ```java
 public final class Hero {
@@ -60,7 +71,7 @@ public final class Hero {
 }
 ```
 
-And then we have the builder
+Then we have the builder:
 
 ```java
   public static class Builder {
@@ -105,20 +116,22 @@ And then we have the builder
   }
 ```
 
-And then it can be used as:
+Then it can be used as:
 
 ```java
 var mage = new Hero.Builder(Profession.MAGE, "Riobard").withHairColor(HairColor.BLACK).withWeapon(Weapon.DAGGER).build();
 ```
 
 ## Class diagram
+
 ![alt text](./etc/builder.urm.png "Builder class diagram")
 
 ## Applicability
+
 Use the Builder pattern when
 
-* the algorithm for creating a complex object should be independent of the parts that make up the object and how they're assembled
-* the construction process must allow different representations for the object that's constructed
+* The algorithm for creating a complex object should be independent of the parts that make up the object and how they're assembled
+* The construction process must allow different representations for the object that's constructed
 
 ## Real world examples
 

builder/pom.xml

@@ -22,7 +22,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.23.0-SNAPSHOT</version>
+		<version>1.24.0-SNAPSHOT</version>
 	</parent>
 	<artifactId>builder</artifactId>
 	<dependencies>

business-delegate/pom.xml

@@ -22,7 +22,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.23.0-SNAPSHOT</version>
+		<version>1.24.0-SNAPSHOT</version>
 	</parent>
 	<artifactId>business-delegate</artifactId>
 	<dependencies>

bytecode/pom.xml

@@ -20,7 +20,7 @@
 	<parent>
 		<artifactId>java-design-patterns</artifactId>
 		<groupId>com.iluwatar</groupId>
-		<version>1.23.0-SNAPSHOT</version>
+		<version>1.24.0-SNAPSHOT</version>
 	</parent>
 	<modelVersion>4.0.0</modelVersion>
 

caching/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.23.0-SNAPSHOT</version>
+    <version>1.24.0-SNAPSHOT</version>
   </parent>
   <artifactId>caching</artifactId>
   <dependencies>

callback/README.md

@@ -9,14 +9,16 @@ tags:
 ---
 
 ## Intent
-Callback is a piece of executable code that is passed as an argument to other code, which is expected to call back 
-(execute) the argument at some convenient time.
+
+Callback is a piece of executable code that is passed as an argument to other code, which is 
+expected to call back (execute) the argument at some convenient time.
 
 ## Explanation
 
 Real world example
 
-> We need to be notified after executing task has finished. We pass a callback method for the executor and wait for it to call back on us.     
+> We need to be notified after executing task has finished. We pass a callback method for 
+> the executor and wait for it to call back on us.     
 
 In plain words
 
@@ -24,7 +26,9 @@ In plain words
 
 Wikipedia says
 
-> In computer programming, a callback, also known as a "call-after" function, is any executable code that is passed as an argument to other code; that other code is expected to call back (execute) the argument at a given time.
+> In computer programming, a callback, also known as a "call-after" function, is any executable 
+> code that is passed as an argument to other code; that other code is expected to call 
+> back (execute) the argument at a given time.
 
 **Programmatic Example**
 
@@ -61,7 +65,7 @@ public final class SimpleTask extends Task {
 }
 ```
 
-Finally here's how we execute a task and receive a callback when it's finished.
+Finally, here's how we execute a task and receive a callback when it's finished.
 
 ```java
     var task = new SimpleTask();
@@ -69,13 +73,15 @@ Finally here's how we execute a task and receive a callback when it's finished.
 ```
 
 ## Class diagram
+
 ![alt text](./etc/callback.png "Callback")
 
 ## Applicability
+
 Use the Callback pattern when
 
 * when some arbitrary synchronous or asynchronous action must be performed after execution of some defined activity.
 
 ## Real world examples
 
-* [CyclicBarrier](http://docs.oracle.com/javase/7/docs/api/java/util/concurrent/CyclicBarrier.html#CyclicBarrier%28int,%20java.lang.Runnable%29) constructor can accept callback that will be triggered every time when barrier is tripped.
+* [CyclicBarrier](http://docs.oracle.com/javase/7/docs/api/java/util/concurrent/CyclicBarrier.html#CyclicBarrier%28int,%20java.lang.Runnable%29) constructor can accept a callback that will be triggered every time a barrier is tripped.

callback/etc/callback.urm.puml

@@ -8,11 +8,6 @@ package com.iluwatar.callback {
   interface Callback {
     + call() {abstract}
   }
-  class LambdasApp {
-    - LOGGER : Logger {static}
-    - LambdasApp()
-    + main(args : String[]) {static}
-  }
   class SimpleTask {
     - LOGGER : Logger {static}
     + SimpleTask()

callback/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.23.0-SNAPSHOT</version>
+    <version>1.24.0-SNAPSHOT</version>
   </parent>
   <artifactId>callback</artifactId>
   <dependencies>

chain/README.md

@@ -9,27 +9,32 @@ tags:
 ---
 
 ## Intent
-Avoid coupling the sender of a request to its receiver by giving
-more than one object a chance to handle the request. Chain the receiving
-objects and pass the request along the chain until an object handles it.
+Avoid coupling the sender of a request to its receiver by giving more than one object a chance to 
+handle the request. Chain the receiving objects and pass the request along the chain until an object 
+handles it.
 
 ## Explanation
 
 Real world example
 
-> The Orc King gives loud orders to his army. The closest one to react is the commander, then officer and then soldier. The commander, officer and soldier here form a chain of responsibility.
+> The Orc King gives loud orders to his army. The closest one to react is the commander, then 
+> officer and then soldier. The commander, officer and soldier here form a chain of responsibility.
 
 In plain words
 
-> It helps building a chain of objects. Request enters from one end and keeps going from object to object till it finds the suitable handler.
+> It helps to build a chain of objects. A request enters from one end and keeps going from an object 
+> to another until it finds a suitable handler.
 
 Wikipedia says
 
-> In object-oriented design, the chain-of-responsibility pattern is a design pattern consisting of a source of command objects and a series of processing objects. Each processing object contains logic that defines the types of command objects that it can handle; the rest are passed to the next processing object in the chain.
+> In object-oriented design, the chain-of-responsibility pattern is a design pattern consisting of 
+> a source of command objects and a series of processing objects. Each processing object contains 
+> logic that defines the types of command objects that it can handle; the rest are passed to the 
+> next processing object in the chain.
 
 **Programmatic Example**
 
-Translating our example with orcs from above. First we have the request class
+Translating our example with the orcs from above. First we have the `Request` class:
 
 ```java
 public class Request {
@@ -140,14 +145,16 @@ king.makeRequest(new Request(RequestType.COLLECT_TAX, "collect tax")); // Orc so
 ```
 
 ## Class diagram
+
 ![alt text](./etc/chain.urm.png "Chain of Responsibility class diagram")
 
 ## Applicability
+
 Use Chain of Responsibility when
 
-* more than one object may handle a request, and the handler isn't known a priori. The handler should be ascertained automatically
-* you want to issue a request to one of several objects without specifying the receiver explicitly
-* the set of objects that can handle a request should be specified dynamically
+* More than one object may handle a request, and the handler isn't known a priori. The handler should be ascertained automatically.
+* You want to issue a request to one of several objects without specifying the receiver explicitly.
+* The set of objects that can handle a request should be specified dynamically.
 
 ## Real world examples
 

chain/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.23.0-SNAPSHOT</version>
+    <version>1.24.0-SNAPSHOT</version>
   </parent>
   <artifactId>chain</artifactId>
   <dependencies>

circuit-breaker/README.md

@@ -12,32 +12,43 @@ tags:
 
 ## Intent
 
-Handle costly remote *procedure/service* calls in such a way that the failure of a **single** service/component cannot bring the whole application down, and we can reconnect to the service as soon as possible.
+Handle costly remote service calls in such a way that the failure of a single service/component 
+cannot bring the whole application down, and we can reconnect to the service as soon as possible.
 
 ## Explanation
 
 Real world example
 
-> Imagine a Web App that has both local (example: files and images) and remote (example: database entries) to serve. The database might not be responding due to a variety of reasons, so if the application keeps trying to read from the database using multiple threads/processes, soon all of them will hang and our entire web application will crash. We should be able to detect this situation and show the user an appropriate message so that he/she can explore other parts of the app unaffected by the database failure without any problem. 
+> Imagine a web application that has both local files/images and remote database entries to serve. 
+> The database might not be responding due to a variety of reasons, so if the application keeps 
+> trying to read from the database using multiple threads/processes, soon all of them will hang 
+> causing our entire web application will crash. We should be able to detect this situation and show 
+> the user an appropriate message so that he/she can explore other parts of the app unaffected by 
+> the database failure. 
 
 In plain words
 
-> Allows us to save resources when we know a remote service failed. Useful when all parts of our application are highly decoupled from each other, and failure of one component doesn't mean the other parts will stop working.
+> Circuit Breaker allows graceful handling of failed remote services. It's especially useful when 
+> all parts of our application are highly decoupled from each other, and failure of one component 
+> doesn't mean the other parts will stop working.
 
 Wikipedia says
 
-> **Circuit breaker** is a design pattern used in modern software development. It is used to detect failures and encapsulates the logic of preventing a failure from constantly recurring, during maintenance, temporary external system failure or unexpected system difficulties.
-
-So, how does this all come together?
+> Circuit breaker is a design pattern used in modern software development. It is used to detect 
+> failures and encapsulates the logic of preventing a failure from constantly recurring, during 
+> maintenance, temporary external system failure or unexpected system difficulties.
 
 ## Programmatic Example
-With the above example in mind we will imitate the functionality in a simple manner. We have two services: A *monitoring service* which will mimic the web app and will make both **local** and **remote** calls.
+
+So, how does this all come together? With the above example in mind we will imitate the 
+functionality in a simple example. A monitoring service mimics the web app and makes both local and 
+remote calls.
 
 The service architecture is as follows:
 
 ![alt text](./etc/ServiceDiagram.PNG "Service Diagram")
 
-In terms of code, the End user application is:
+In terms of code, the end user application is:
 
 ```java
 public class App {
@@ -62,7 +73,7 @@ public class App {
 }
 ```
 
-The monitoring service is: 
+The monitoring service: 
 
 ``` java
 public class MonitoringService {
@@ -80,7 +91,8 @@ public class MonitoringService {
   }
 }
 ```
-As it can be seen, it does the call to get local resources directly, but it wraps the call to remote (costly) service in a circuit breaker object, which prevents faults as follows:
+As it can be seen, it does the call to get local resources directly, but it wraps the call to 
+remote (costly) service in a circuit breaker object, which prevents faults as follows:
 
 ```java
 public class CircuitBreaker {
@@ -155,24 +167,27 @@ public class CircuitBreaker {
 }
 ```
 
-How does the above pattern prevent failures? Let's understand via this finite state machine implemented by it.
+How does the above pattern prevent failures? Let's understand via this finite state machine 
+implemented by it.
 
 ![alt text](./etc/StateDiagram.PNG "State Diagram")
 
-- We initialize the Circuit Breaker object with certain parameters: **timeout**, **failureThreshold** and **retryTimePeriod** which help determine how resilient the API is.
-- Initially, we are in the **closed** state and the remote call to API happens.
+- We initialize the Circuit Breaker object with certain parameters: `timeout`, `failureThreshold` and `retryTimePeriod` which help determine how resilient the API is.
+- Initially, we are in the `closed` state and nos remote calls to the API have occurred.
 - Every time the call succeeds, we reset the state to as it was in the beginning.
-- If the number of failures cross a certain threshold, we move to the **open** state, which acts just like an open circuit and prevents remote service calls from being made, thus saving resources. (Here, we return the response called ```stale response from API```)
-- Once we exceed the retry timeout period, we move to the **half-open** state and make another call to the remote service again to check if the service is working so that we can serve fresh content. A *failure* sets it back to **open** state and another attempt is made after retry timeout period, while a *success* sets it to **closed** state so that everything starts working normally again. 
+- If the number of failures cross a certain threshold, we move to the `open` state, which acts just like an open circuit and prevents remote service calls from being made, thus saving resources. (Here, we return the response called ```stale response from API```)
+- Once we exceed the retry timeout period, we move to the `half-open` state and make another call to the remote service again to check if the service is working so that we can serve fresh content. A failure sets it back to `open` state and another attempt is made after retry timeout period, while a success sets it to `closed` state so that everything starts working normally again. 
 
 ## Class diagram
+
 ![alt text](./etc/circuit-breaker.urm.png "Circuit Breaker class diagram")
 
 ## Applicability
+
 Use the Circuit Breaker pattern when
 
 - Building a fault-tolerant application where failure of some services shouldn't bring the entire application down.
-- Building an continuously incremental/continuous delivery application, as some of it's components can be upgraded without shutting it down entirely.
+- Building a continuously running (always-on) application, so that its components can be upgraded without shutting it down entirely.
 
 ## Related Patterns
 

circuit-breaker/pom.xml

@@ -27,7 +27,7 @@
     <parent>
         <groupId>com.iluwatar</groupId>
         <artifactId>java-design-patterns</artifactId>
-        <version>1.23.0-SNAPSHOT</version>
+        <version>1.24.0-SNAPSHOT</version>
     </parent>
     <artifactId>circuit-breaker</artifactId>
     <dependencies>

collection-pipeline/pom.xml

@@ -27,7 +27,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.23.0-SNAPSHOT</version>
+    <version>1.24.0-SNAPSHOT</version>
   </parent>
   <artifactId>collection-pipeline</artifactId>
   <dependencies>

combinator/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.23.0-SNAPSHOT</version>
+    <version>1.24.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>combinator</artifactId>

command/README.md

@@ -9,15 +9,20 @@ tags:
 ---
 
 ## Also known as
+
 Action, Transaction
 
 ## Intent
-Encapsulate a request as an object, thereby letting you parameterize clients with different requests, queue or log requests, and support undoable operations.
+
+Encapsulate a request as an object, thereby letting you parameterize clients with different 
+requests, queue or log requests, and support undoable operations.
 
 ## Explanation
 Real world example
 
-> There is a wizard casting spells on a goblin. The spells are executed on the goblin one by one. The first spell shrinks the goblin and the second makes him invisible. Then the wizard reverses the spells one by one. Each spell here is a command object that can be undone.
+> There is a wizard casting spells on a goblin. The spells are executed on the goblin one by one. 
+> The first spell shrinks the goblin and the second makes him invisible. Then the wizard reverses 
+> the spells one by one. Each spell here is a command object that can be undone.
 
 In plain words
 
@@ -25,11 +30,13 @@ In plain words
 
 Wikipedia says
 
-> In object-oriented programming, the command pattern is a behavioral design pattern in which an object is used to encapsulate all information needed to perform an action or trigger an event at a later time.
+> In object-oriented programming, the command pattern is a behavioral design pattern in which an 
+> object is used to encapsulate all information needed to perform an action or trigger an event at 
+> a later time.
 
 **Programmatic Example**
 
-Here's the sample code with wizard and goblin. Let's start from the wizard class.
+Here's the sample code with wizard and goblin. Let's start from the `Wizard` class.
 
 ```java
 public class Wizard {
@@ -149,7 +156,7 @@ public class ShrinkSpell implements Command {
 }
 ```
 
-And last we have the goblin who's the target of the spells.
+Finally, we have the goblin who's the target of the spells.
 
 ```java
 public abstract class Target {
@@ -199,44 +206,67 @@ public class Goblin extends Target {
 }
 ```
 
-Finally here's the whole example in action.
+Here's the whole example in action.
 
 ```java
 var wizard = new Wizard();
 var goblin = new Goblin();
 goblin.printStatus();
-// Goblin, [size=normal] [visibility=visible]
 wizard.castSpell(new ShrinkSpell(), goblin);
-// Wizard casts Shrink spell at Goblin
 goblin.printStatus();
-// Goblin, [size=small] [visibility=visible]
 wizard.castSpell(new InvisibilitySpell(), goblin);
-// Wizard casts Invisibility spell at Goblin
 goblin.printStatus();
-// Goblin, [size=small] [visibility=invisible]
 wizard.undoLastSpell();
-// Wizard undoes Invisibility spell
 goblin.printStatus();
+```
+
+Here's the program output:
+
+```java
+// Goblin, [size=normal] [visibility=visible]
+// Wizard casts Shrink spell at Goblin
+// Goblin, [size=small] [visibility=visible]
+// Wizard casts Invisibility spell at Goblin
+// Goblin, [size=small] [visibility=invisible]
+// Wizard undoes Invisibility spell
 // Goblin, [size=small] [visibility=visible]
 ```
 
 ## Class diagram
+
 ![alt text](./etc/command.png "Command")
 
 ## Applicability
-Use the Command pattern when you want to
 
-* parameterize objects by an action to perform. You can express such parameterization in a procedural language with a callback function, that is, a function that's registered somewhere to be called at a later point. Commands are an object-oriented replacement for callbacks.
-* specify, queue, and execute requests at different times. A Command object can have a lifetime independent of the original request. If the receiver of a request can be represented in an address space-independent way, then you can transfer a command object for the request to a different process and fulfill the request there
-* support undo. The Command's execute operation can store state for reversing its effects in the command itself. The Command interface must have an added Unexecute operation that reverses the effects of a previous call to execute. Executed commands are stored in a history list. Unlimited-level undo and redo is achieved by traversing this list backwards and forwards calling unexecute and execute, respectively
-* support logging changes so that they can be reapplied in case of a system crash. By augmenting the Command interface with load and store operations, you can keep a persistent log of changes. Recovering from a crash involves reloading logged commands from disk and re-executing them with the execute operation
-* structure a system around high-level operations build on primitive operations. Such a structure is common in information systems that support transactions. A transaction encapsulates a set of changes to data. The Command pattern offers a way to model transactions. Commands have a common interface, letting you invoke all transactions the same way. The pattern also makes it easy to extend the system with new transactions
+Use the Command pattern when you want to:
+
+* Parameterize objects by an action to perform. You can express such parameterization in a 
+procedural language with a callback function, that is, a function that's registered somewhere to be 
+called at a later point. Commands are an object-oriented replacement for callbacks.
+* Specify, queue, and execute requests at different times. A Command object can have a lifetime 
+independent of the original request. If the receiver of a request can be represented in an address 
+space-independent way, then you can transfer a command object for the request to a different process 
+and fulfill the request there.
+* Support undo. The Command's execute operation can store state for reversing its effects in the 
+command itself. The Command interface must have an added un-execute operation that reverses the 
+effects of a previous call to execute. The executed commands are stored in a history list. 
+Unlimited-level undo and redo is achieved by traversing this list backwards and forwards calling 
+un-execute and execute, respectively.
+* Support logging changes so that they can be reapplied in case of a system crash. By augmenting the 
+Command interface with load and store operations, you can keep a persistent log of changes. 
+Recovering from a crash involves reloading logged commands from disk and re-executing them with 
+the execute operation.
+* Structure a system around high-level operations build on primitive operations. Such a structure is 
+common in information systems that support transactions. A transaction encapsulates a set of changes 
+to data. The Command pattern offers a way to model transactions. Commands have a common interface, 
+letting you invoke all transactions the same way. The pattern also makes it easy to extend the 
+system with new transactions.
 
 ## Typical Use Case
 
-* to keep a history of requests
-* implement callback functionality
-* implement the undo functionality
+* To keep a history of requests
+* Implement callback functionality
+* Implement the undo functionality
 
 ## Real world examples
 

command/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.23.0-SNAPSHOT</version>
+    <version>1.24.0-SNAPSHOT</version>
   </parent>
   <artifactId>command</artifactId>
   <dependencies>

commander/pom.xml

@@ -27,7 +27,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.23.0-SNAPSHOT</version>
+    <version>1.24.0-SNAPSHOT</version>
   </parent>
   <artifactId>commander</artifactId>
   <dependencies>

composite/README.md

@@ -9,15 +9,17 @@ tags:
 ---
 
 ## Intent
-Compose objects into tree structures to represent part-whole
-hierarchies. Composite lets clients treat individual objects and compositions
-of objects uniformly.
+
+Compose objects into tree structures to represent part-whole hierarchies. Composite lets clients 
+treat individual objects and compositions of objects uniformly.
 
 ## Explanation
 
 Real world example
 
-> Every sentence is composed of words which are in turn composed of characters. Each of these objects is printable and they can have something printed before or after them like sentence always ends with full stop and word always has space before it
+> Every sentence is composed of words which are in turn composed of characters. Each of these 
+> objects is printable and they can have something printed before or after them like sentence always 
+> ends with full stop and word always has space before it.
 
 In plain words
 
@@ -25,11 +27,16 @@ In plain words
 
 Wikipedia says
 
-> In software engineering, the composite pattern is a partitioning design pattern. The composite pattern describes that a group of objects is to be treated in the same way as a single instance of an object. The intent of a composite is to "compose" objects into tree structures to represent part-whole hierarchies. Implementing the composite pattern lets clients treat individual objects and compositions uniformly.
+> In software engineering, the composite pattern is a partitioning design pattern. The composite 
+> pattern describes that a group of objects is to be treated in the same way as a single instance of 
+> an object. The intent of a composite is to "compose" objects into tree structures to represent 
+> part-whole hierarchies. Implementing the composite pattern lets clients treat individual objects 
+> and compositions uniformly.
 
 **Programmatic Example**
 
-Taking our sentence example from above. Here we have the base class and different printable types
+Taking our sentence example from above. Here we have the base class `LetterComposite` and the 
+different printable types `Letter`, `Word` and `Sentence`. 
 
 ```java
 public abstract class LetterComposite {
@@ -102,7 +109,7 @@ public class Sentence extends LetterComposite {
 }
 ```
 
-Then we have a messenger to carry messages
+Then we have a messenger to carry messages:
 
 ```java
 public class Messenger {
@@ -143,7 +150,7 @@ public class Messenger {
 }
 ```
 
-And then it can be used as
+And then it can be used as:
 
 ```java
 var orcMessage = new Messenger().messageFromOrcs();
@@ -153,13 +160,16 @@ elfMessage.print(); // Much wind pours from your mouth.
 ```
 
 ## Class diagram
+
 ![alt text](./etc/composite.urm.png "Composite class diagram")
 
 ## Applicability
+
 Use the Composite pattern when
 
-* you want to represent part-whole hierarchies of objects
-* you want clients to be able to ignore the difference between compositions of objects and individual objects. Clients will treat all objects in the composite structure uniformly
+* You want to represent part-whole hierarchies of objects.
+* You want clients to be able to ignore the difference between compositions of objects and 
+individual objects. Clients will treat all objects in the composite structure uniformly.
 
 ## Real world examples
 

composite/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.23.0-SNAPSHOT</version>
+    <version>1.24.0-SNAPSHOT</version>
   </parent>
   <artifactId>composite</artifactId>
   <dependencies>

converter/README.md

@@ -9,16 +9,19 @@ tags:
 ---
 
 ## Intent
-The purpose of the Converter Pattern is to provide a generic, common way of bidirectional
+
+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
+need to be aware of each other. Moreover, the Converter pattern introduces bidirectional collection
 mapping, reducing a boilerplate code to minimum.
 
 ## Explanation
 
 Real world example
 
-> In real world applications it is often the case that database layer consists of entities that need to be mapped into DTOs for use on the business logic layer. Similar mapping is done for potentially huge amount of classes and we need a generic way to achieve this.
+> In real world applications it is often the case that database layer consists of entities that need 
+> to be mapped into DTOs for use on the business logic layer. Similar mapping is done for 
+> potentially huge amount of classes and we need a generic way to achieve this.
 
 In plain words
 
@@ -26,7 +29,8 @@ In plain words
 
 **Programmatic Example**
 
-We need a generic solution for the mapping problem. To achieve this, let's introduce a generic converter.
+We need a generic solution for the mapping problem. To achieve this, let's introduce a generic 
+converter.
 
 ```java
 public class Converter<T, U> {
@@ -77,7 +81,7 @@ public class UserConverter extends Converter<UserDto, User> {
 }
 ```
 
-Now mapping between User and UserDto becomes trivial.
+Now mapping between `User` and `UserDto` becomes trivial.
 
 ```java
 var userConverter = new UserConverter();
@@ -86,14 +90,18 @@ var user = userConverter.convertFromDto(dtoUser);
 ```
 
 ## Class diagram
+
 ![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
+* When you have types that logically correspond with each other and you need to convert entities 
+between them.
+* When you want to provide different ways of types conversions depending on the context.
+* Whenever you introduce a DTO (Data transfer object), you will probably need to convert it into the 
+domain equivalence.
 
 ## Credits
 

converter/pom.xml

@@ -20,7 +20,7 @@
 	<parent>
 		<artifactId>java-design-patterns</artifactId>
 		<groupId>com.iluwatar</groupId>
-		<version>1.23.0-SNAPSHOT</version>
+		<version>1.24.0-SNAPSHOT</version>
 	</parent>
 	<artifactId>converter</artifactId>
 	<modelVersion>4.0.0</modelVersion>

cqrs/pom.xml

@@ -30,7 +30,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.23.0-SNAPSHOT</version>
+		<version>1.24.0-SNAPSHOT</version>
 	</parent>
 	<artifactId>cqrs</artifactId>
 	<dependencies>

dao/README.md

@@ -9,13 +9,15 @@ tags:
 ---
 
 ## Intent
+
 Object provides an abstract interface to some type of database or other persistence mechanism.
 
 ## Explanation
 
 Real world example
 
-> There's a set of customers that need to be persisted to database. Additionally we need the whole set of CRUD (create/read/update/delete) operations so we can operate on customers easily. 
+> There's a set of customers that need to be persisted to database. Additionally we need the whole 
+> set of CRUD (create/read/update/delete) operations so we can operate on customers easily. 
 
 In plain words
 
@@ -23,11 +25,12 @@ In plain words
 
 Wikipedia says
 
-> In computer software, a data access object (DAO) is a pattern that provides an abstract interface to some type of database or other persistence mechanism.
+> In computer software, a data access object (DAO) is a pattern that provides an abstract interface 
+> to some type of database or other persistence mechanism.
 
 **Programmatic Example**
 
-Walking through our customers example, here's the basic Customer entity.
+Walking through our customers example, here's the basic `Customer` entity.
 
 ```java
 public class Customer {
@@ -41,60 +44,13 @@ public class Customer {
     this.firstName = firstName;
     this.lastName = lastName;
   }
-
-  public int getId() {
-    return id;
-  }
-
-  public void setId(final int id) {
-    this.id = id;
-  }
-
-  public String getFirstName() {
-    return firstName;
-  }
-
-  public void setFirstName(final String firstName) {
-    this.firstName = firstName;
-  }
-
-  public String getLastName() {
-    return lastName;
-  }
-
-  public void setLastName(final String lastName) {
-    this.lastName = lastName;
-  }
-
-  @Override
-  public String toString() {
-    return "Customer{" + "id=" + getId() + ", firstName='" + getFirstName() + '\'' + ", lastName='"
-        + getLastName() + '\'' + '}';
-  }
-
-  @Override
-  public boolean equals(final Object that) {
-    var isEqual = false;
-    if (this == that) {
-      isEqual = true;
-    } else if (that != null && getClass() == that.getClass()) {
-      final var customer = (Customer) that;
-      if (getId() == customer.getId()) {
-        isEqual = true;
-      }
-    }
-    return isEqual;
-  }
-
-  @Override
-  public int hashCode() {
-    return getId();
-  }
+  // getters and setters ->
+  ...
 }
 ```
 
-Here's the DAO interface and two different implementations for it. InMemoryCustomerDao keeps a simple map of customers 
-in memory while DBCustomerDao is the real RDBMS implementation.
+Here's the `CustomerDao` interface and two different implementations for it. `InMemoryCustomerDao` 
+keeps a simple map of customers in memory while `DBCustomerDao` is the real RDBMS implementation.
 
 ```java
 public interface CustomerDao {
@@ -114,35 +70,8 @@ public class InMemoryCustomerDao implements CustomerDao {
 
   private final Map<Integer, Customer> idToCustomer = new HashMap<>();
 
-  @Override
-  public Stream<Customer> getAll() {
-    return idToCustomer.values().stream();
-  }
-
-  @Override
-  public Optional<Customer> getById(final int id) {
-    return Optional.ofNullable(idToCustomer.get(id));
-  }
-
-  @Override
-  public boolean add(final Customer customer) {
-    if (getById(customer.getId()).isPresent()) {
-      return false;
-    }
-
-    idToCustomer.put(customer.getId(), customer);
-    return true;
-  }
-
-  @Override
-  public boolean update(final Customer customer) {
-    return idToCustomer.replace(customer.getId(), customer) != null;
-  }
-
-  @Override
-  public boolean delete(final Customer customer) {
-    return idToCustomer.remove(customer.getId()) != null;
-  }
+  // implement the interface using the map
+  ...
 }
 
 public class DbCustomerDao implements CustomerDao {
@@ -155,121 +84,8 @@ public class DbCustomerDao implements CustomerDao {
     this.dataSource = dataSource;
   }
 
-  @Override
-  public Stream<Customer> getAll() throws Exception {
-    try {
-      var connection = getConnection();
-      var statement = connection.prepareStatement("SELECT * FROM CUSTOMERS");
-      var resultSet = statement.executeQuery();
-      return StreamSupport.stream(new Spliterators.AbstractSpliterator<Customer>(Long.MAX_VALUE,
-          Spliterator.ORDERED) {
-
-        @Override
-        public boolean tryAdvance(Consumer<? super Customer> action) {
-          try {
-            if (!resultSet.next()) {
-              return false;
-            }
-            action.accept(createCustomer(resultSet));
-            return true;
-          } catch (SQLException e) {
-            throw new RuntimeException(e);
-          }
-        }
-      }, false).onClose(() -> mutedClose(connection, statement, resultSet));
-    } catch (SQLException e) {
-      throw new CustomException(e.getMessage(), e);
-    }
-  }
-
-  private Connection getConnection() throws SQLException {
-    return dataSource.getConnection();
-  }
-
-  private void mutedClose(Connection connection, PreparedStatement statement, ResultSet resultSet) {
-    try {
-      resultSet.close();
-      statement.close();
-      connection.close();
-    } catch (SQLException e) {
-      LOGGER.info("Exception thrown " + e.getMessage());
-    }
-  }
-
-  private Customer createCustomer(ResultSet resultSet) throws SQLException {
-    return new Customer(resultSet.getInt("ID"),
-        resultSet.getString("FNAME"),
-        resultSet.getString("LNAME"));
-  }
-
-  @Override
-  public Optional<Customer> getById(int id) throws Exception {
-
-    ResultSet resultSet = null;
-
-    try (var connection = getConnection();
-         var statement = connection.prepareStatement("SELECT * FROM CUSTOMERS WHERE ID = ?")) {
-
-      statement.setInt(1, id);
-      resultSet = statement.executeQuery();
-      if (resultSet.next()) {
-        return Optional.of(createCustomer(resultSet));
-      } else {
-        return Optional.empty();
-      }
-    } catch (SQLException ex) {
-      throw new CustomException(ex.getMessage(), ex);
-    } finally {
-      if (resultSet != null) {
-        resultSet.close();
-      }
-    }
-  }
-
-  @Override
-  public boolean add(Customer customer) throws Exception {
-    if (getById(customer.getId()).isPresent()) {
-      return false;
-    }
-
-    try (var connection = getConnection();
-         var statement = connection.prepareStatement("INSERT INTO CUSTOMERS VALUES (?,?,?)")) {
-      statement.setInt(1, customer.getId());
-      statement.setString(2, customer.getFirstName());
-      statement.setString(3, customer.getLastName());
-      statement.execute();
-      return true;
-    } catch (SQLException ex) {
-      throw new CustomException(ex.getMessage(), ex);
-    }
-  }
-
-  @Override
-  public boolean update(Customer customer) throws Exception {
-    try (var connection = getConnection();
-         var statement =
-             connection
-                 .prepareStatement("UPDATE CUSTOMERS SET FNAME = ?, LNAME = ? WHERE ID = ?")) {
-      statement.setString(1, customer.getFirstName());
-      statement.setString(2, customer.getLastName());
-      statement.setInt(3, customer.getId());
-      return statement.executeUpdate() > 0;
-    } catch (SQLException ex) {
-      throw new CustomException(ex.getMessage(), ex);
-    }
-  }
-
-  @Override
-  public boolean delete(Customer customer) throws Exception {
-    try (var connection = getConnection();
-         var statement = connection.prepareStatement("DELETE FROM CUSTOMERS WHERE ID = ?")) {
-      statement.setInt(1, customer.getId());
-      return statement.executeUpdate() > 0;
-    } catch (SQLException ex) {
-      throw new CustomException(ex.getMessage(), ex);
-    }
-  }
-}
+  // implement the interface using the data source
+  ...
 ```
 
 Finally here's how we use our DAO to manage customers.
@@ -301,15 +117,45 @@ Finally here's how we use our DAO to manage customers.
     deleteSchema(dataSource);
 ```
 
+The program output:
+
+```java
+customerDao.getAllCustomers(): 
+Customer{id=1, firstName='Adam', lastName='Adamson'}
+Customer{id=2, firstName='Bob', lastName='Bobson'}
+Customer{id=3, firstName='Carl', lastName='Carlson'}
+customerDao.getCustomerById(2): Optional[Customer{id=2, firstName='Bob', lastName='Bobson'}]
+customerDao.getAllCustomers(): java.util.stream.ReferencePipeline$Head@7cef4e59
+customerDao.getAllCustomers(): 
+Customer{id=1, firstName='Adam', lastName='Adamson'}
+Customer{id=2, firstName='Bob', lastName='Bobson'}
+Customer{id=3, firstName='Carl', lastName='Carlson'}
+Customer{id=4, firstName='Daniel', lastName='Danielson'}
+customerDao.getAllCustomers(): java.util.stream.ReferencePipeline$Head@2db0f6b2
+customerDao.getAllCustomers(): 
+Customer{id=1, firstName='Adam', lastName='Adamson'}
+Customer{id=2, firstName='Bob', lastName='Bobson'}
+Customer{id=3, firstName='Carl', lastName='Carlson'}
+customerDao.getCustomerById(2): Optional[Customer{id=2, firstName='Bob', lastName='Bobson'}]
+customerDao.getAllCustomers(): java.util.stream.ReferencePipeline$Head@12c8a2c0
+customerDao.getAllCustomers(): 
+Customer{id=1, firstName='Adam', lastName='Adamson'}
+Customer{id=2, firstName='Bob', lastName='Bobson'}
+Customer{id=3, firstName='Carl', lastName='Carlson'}
+Customer{id=4, firstName='Daniel', lastName='Danielson'}
+customerDao.getAllCustomers(): java.util.stream.ReferencePipeline$Head@6ec8211c
+```
 
 ## Class diagram
+
 ![alt text](./etc/dao.png "Data Access Object")
 
 ## Applicability
-Use the Data Access Object in any of the following situations
 
-* when you want to consolidate how the data layer is accessed
-* when you want to avoid writing multiple data retrieval/persistence layers
+Use the Data Access Object in any of the following situations:
+
+* When you want to consolidate how the data layer is accessed.
+* When you want to avoid writing multiple data retrieval/persistence layers.
 
 ## Credits
 

dao/pom.xml

@@ -30,7 +30,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.23.0-SNAPSHOT</version>
+    <version>1.24.0-SNAPSHOT</version>
   </parent>
   <artifactId>dao</artifactId>
 

data-bus/pom.xml

@@ -33,7 +33,7 @@
     <parent>
         <groupId>com.iluwatar</groupId>
         <artifactId>java-design-patterns</artifactId>
-        <version>1.23.0-SNAPSHOT</version>
+        <version>1.24.0-SNAPSHOT</version>
     </parent>
     <artifactId>data-bus</artifactId>
     <dependencies>

data-locality/pom.xml

@@ -30,7 +30,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.23.0-SNAPSHOT</version>
+    <version>1.24.0-SNAPSHOT</version>
   </parent>
   <artifactId>data-locality</artifactId>
 

data-mapper/pom.xml

@@ -28,7 +28,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.23.0-SNAPSHOT</version>
+		<version>1.24.0-SNAPSHOT</version>
 	</parent>
 	<artifactId>data-mapper</artifactId>
 	<dependencies>

data-transfer-object/README.md

@@ -9,13 +9,16 @@ tags:
 ---
 
 ## Intent
-Pass data with multiple attributes in one shot from client to server, to avoid multiple calls to remote server. 
+
+Pass data with multiple attributes in one shot from client to server, to avoid multiple calls to 
+remote server. 
 
 ## Explanation
 
 Real world example
 
-> We need to fetch information about customers from remote database. Instead of querying the attributes one at a time, we use DTOs to transfer all the relevant attributes in a single shot.     
+> We need to fetch information about customers from remote database. Instead of querying the 
+> attributes one at a time, we use DTOs to transfer all the relevant attributes in a single shot.     
 
 In plain words
 
@@ -23,16 +26,17 @@ In plain words
 
 Wikipedia says
 
-> In the field of programming a data transfer object (DTO) is an object that carries data between processes. The 
-motivation for its use is that communication between processes is usually done resorting to remote interfaces 
-(e.g., web services), where each call is an expensive operation. Because the majority of the cost of each call is 
-related to the round-trip time between the client and the server, one way of reducing the number of calls is to use an 
-object (the DTO) that aggregates the data that would have been transferred by the several calls, but that is served by 
-one call only.
+> In the field of programming a data transfer object (DTO) is an object that carries data between 
+> processes. The motivation for its use is that communication between processes is usually done 
+> resorting to remote interfaces (e.g. web services), where each call is an expensive operation. 
+> Because the majority of the cost of each call is related to the round-trip time between the client 
+> and the server, one way of reducing the number of calls is to use an object (the DTO) that 
+> aggregates the data that would have been transferred by the several calls, but that is served by 
+> one call only.
 
 **Programmatic Example**
 
-Let's first introduce our simple customer DTO class.
+Let's first introduce our simple `CustomerDTO` class.
 
 ```java
 public class CustomerDto {
@@ -60,7 +64,7 @@ public class CustomerDto {
 }
 ```
 
-Customer resource class acts as the server for customer information.
+`CustomerResource` class acts as the server for customer information.
 
 ```java
 public class CustomerResource {
@@ -94,10 +98,12 @@ Now fetching customer information is easy since we have the DTOs.
 ```
 
 ## Class diagram
+
 ![alt text](./etc/data-transfer-object.urm.png "data-transfer-object")
 
 ## Applicability
-Use the Data Transfer Object pattern when
+
+Use the Data Transfer Object pattern when:
 
 * The client is asking for multiple information. And the information is related.
 * When you want to boost the performance to get resources.

data-transfer-object/pom.xml

@@ -28,7 +28,7 @@
     <parent>
         <groupId>com.iluwatar</groupId>
         <artifactId>java-design-patterns</artifactId>
-        <version>1.23.0-SNAPSHOT</version>
+        <version>1.24.0-SNAPSHOT</version>
     </parent>
     <artifactId>data-transfer-object</artifactId>
     <dependencies>

decorator/README.md

@@ -10,30 +10,39 @@ tags:
 ---
 
 ## Also known as
+
 Wrapper
 
 ## Intent
-Attach additional responsibilities to an object dynamically.
-Decorators provide a flexible alternative to subclassing for extending
-functionality.
+
+Attach additional responsibilities to an object dynamically. Decorators provide a flexible 
+alternative to subclassing for extending functionality.
 
 ## Explanation
 
 Real world example
 
-> There is an angry troll living in the nearby hills. Usually it goes bare handed but sometimes it has a weapon. To arm the troll it's not necessary to create a new troll but to decorate it dynamically with a suitable weapon.
+> There is an angry troll living in the nearby hills. Usually it goes bare handed but sometimes it 
+> has a weapon. To arm the troll it's not necessary to create a new troll but to decorate it 
+> dynamically with a suitable weapon.
 
 In plain words
 
-> Decorator pattern lets you dynamically change the behavior of an object at run time by wrapping them in an object of a decorator class.
+> Decorator pattern lets you dynamically change the behavior of an object at run time by wrapping 
+> them in an object of a decorator class.
 
 Wikipedia says
 
-> In object-oriented programming, the decorator pattern is a design pattern that allows behavior to be added to an individual object, either statically or dynamically, without affecting the behavior of other objects from the same class. The decorator pattern is often useful for adhering to the Single Responsibility Principle, as it allows functionality to be divided between classes with unique areas of concern.
+> In object-oriented programming, the decorator pattern is a design pattern that allows behavior to 
+> be added to an individual object, either statically or dynamically, without affecting the behavior 
+> of other objects from the same class. The decorator pattern is often useful for adhering to the 
+> Single Responsibility Principle, as it allows functionality to be divided between classes with 
+> unique areas of concern.
 
 **Programmatic Example**
 
-Let's take the troll example. First of all we have a simple troll implementing the troll interface
+Let's take the troll example. First of all we have a `SimpleTroll` implementing the `Troll` 
+interface:
 
 ```java
 public interface Troll {
@@ -63,7 +72,7 @@ public class SimpleTroll implements Troll {
 }
 ```
 
-Next we want to add club for the troll. We can do it dynamically by using a decorator
+Next we want to add club for the troll. We can do it dynamically by using a decorator:
 
 ```java
 public class ClubbedTroll implements Troll {
@@ -94,7 +103,7 @@ public class ClubbedTroll implements Troll {
 }
 ```
 
-Here's the troll in action
+Here's the troll in action:
 
 ```java
 // simple troll
@@ -108,20 +117,36 @@ clubbedTroll.attack(); // The troll tries to grab you! The troll swings at you w
 clubbedTroll.fleeBattle(); // The troll shrieks in horror and runs away!
 ```
 
+Program output:
+
+```java
+The troll tries to grab you!
+The troll shrieks in horror and runs away!
+The troll tries to grab you! The troll swings at you with a club!
+The troll shrieks in horror and runs away!
+```
+
 ## Class diagram
+
 ![alt text](./etc/decorator.urm.png "Decorator pattern class diagram")
 
 ## Applicability
-Use Decorator
 
-* To add responsibilities to individual objects dynamically and transparently, that is, without affecting other objects
-* For responsibilities that can be withdrawn
-* When extension by subclassing is impractical. Sometimes a large number of independent extensions are possible and would produce an explosion of subclasses to support every combination. Or a class definition may be hidden or otherwise unavailable for subclassing
+Decorator is used to:
+
+* Add responsibilities to individual objects dynamically and transparently, that is, without 
+affecting other objects.
+* For responsibilities that can be withdrawn.
+* When extension by subclassing is impractical. Sometimes a large number of independent extensions 
+are possible and would produce an explosion of subclasses to support every combination. Or a class 
+definition may be hidden or otherwise unavailable for subclassing.
 
 ## Tutorial
+
 * [Decorator Pattern Tutorial](https://www.journaldev.com/1540/decorator-design-pattern-in-java-example)
 
 ## Real world examples
+
  * [java.io.InputStream](http://docs.oracle.com/javase/8/docs/api/java/io/InputStream.html), [java.io.OutputStream](http://docs.oracle.com/javase/8/docs/api/java/io/OutputStream.html),
  [java.io.Reader](http://docs.oracle.com/javase/8/docs/api/java/io/Reader.html) and [java.io.Writer](http://docs.oracle.com/javase/8/docs/api/java/io/Writer.html)
  * [java.util.Collections#synchronizedXXX()](http://docs.oracle.com/javase/8/docs/api/java/util/Collections.html#synchronizedCollection-java.util.Collection-)

decorator/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.23.0-SNAPSHOT</version>
+    <version>1.24.0-SNAPSHOT</version>
   </parent>
   <artifactId>decorator</artifactId>
   <dependencies>

delegation/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <artifactId>java-design-patterns</artifactId>
     <groupId>com.iluwatar</groupId>
-    <version>1.23.0-SNAPSHOT</version>
+    <version>1.24.0-SNAPSHOT</version>
   </parent>
   <modelVersion>4.0.0</modelVersion>
 

dependency-injection/README.md

@@ -9,15 +9,19 @@ tags:
 ---
 
 ## Intent
-Dependency Injection is a software design pattern in which one or more dependencies (or services) are injected, or 
-passed by reference, into a dependent object (or client) and are made part of the client's state. The pattern separates 
-the creation of a client's dependencies from its own behavior, which allows program designs to be loosely coupled and 
-to follow the inversion of control and single responsibility principles.
+
+Dependency Injection is a software design pattern in which one or more dependencies (or services) 
+are injected, or passed by reference, into a dependent object (or client) and are made part of the 
+client's state. The pattern separates the creation of a client's dependencies from its own behavior, 
+which allows program designs to be loosely coupled and to follow the inversion of control and single 
+responsibility principles.
 
 ## Explanation
+
 Real world example
 
-> The old wizard likes to fill his pipe and smoke tobacco once in a while. However, he doesn't want to depend on a single tobacco brand only but likes to be able to enjoy them all interchangeably.    
+> The old wizard likes to fill his pipe and smoke tobacco once in a while. However, he doesn't want 
+> to depend on a single tobacco brand only but likes to be able to enjoy them all interchangeably.    
 
 In plain words
 
@@ -25,11 +29,12 @@ In plain words
 
 Wikipedia says
 
-> In software engineering, dependency injection is a technique in which an object receives other objects that it depends on. These other objects are called dependencies.
+> In software engineering, dependency injection is a technique in which an object receives other 
+> objects that it depends on. These other objects are called dependencies.
 
 **Programmatic Example**
 
-Let's first introduce the tobacco brands.
+Let's first introduce the `Tobacco` interface and the concrete brands.
 
 ```java
 public abstract class Tobacco {
@@ -52,7 +57,7 @@ public class OldTobyTobacco extends Tobacco {
 }
 ```
 
-Next here's the wizard class hierarchy.
+Next here's the `Wizard` class hierarchy.
 
 ```java
 public interface Wizard {
@@ -83,13 +88,15 @@ And lastly we can show how easy it is to give the old wizard any brand of tobacc
 ```
 
 ## Class diagram
+
 ![alt text](./etc/dependency-injection.png "Dependency Injection")
 
 ## Applicability
-Use the Dependency Injection pattern when
 
-* When you need to remove knowledge of concrete implementation from object
-* To enable unit testing of classes in isolation using mock objects or stubs
+Use the Dependency Injection pattern when:
+
+* When you need to remove knowledge of concrete implementation from object.
+* To enable unit testing of classes in isolation using mock objects or stubs.
 
 ## Credits
 

dependency-injection/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.23.0-SNAPSHOT</version>
+    <version>1.24.0-SNAPSHOT</version>
   </parent>
   <artifactId>dependency-injection</artifactId>
   <dependencies>

dirty-flag/pom.xml

@@ -29,10 +29,10 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.23.0-SNAPSHOT</version>
+    <version>1.24.0-SNAPSHOT</version>
   </parent>
   <artifactId>dirty-flag</artifactId>
-  <version>1.23.0-SNAPSHOT</version>
+  <version>1.24.0-SNAPSHOT</version>
   <name>dirty-flag</name>
   <url>http://maven.apache.org</url>
   <properties>

double-buffer/pom.xml

@@ -29,7 +29,7 @@
     <parent>
         <artifactId>java-design-patterns</artifactId>
         <groupId>com.iluwatar</groupId>
-        <version>1.23.0-SNAPSHOT</version>
+        <version>1.24.0-SNAPSHOT</version>
     </parent>
     <modelVersion>4.0.0</modelVersion>
 

double-checked-locking/pom.xml

@@ -27,7 +27,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.23.0-SNAPSHOT</version>
+    <version>1.24.0-SNAPSHOT</version>
   </parent>
   <artifactId>double-checked-locking</artifactId>
   <dependencies>

double-dispatch/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.23.0-SNAPSHOT</version>
+    <version>1.24.0-SNAPSHOT</version>
   </parent>
   <artifactId>double-dispatch</artifactId>
   <dependencies>

eip-aggregator/pom.xml

@@ -31,7 +31,7 @@
     <parent>
         <groupId>com.iluwatar</groupId>
         <artifactId>java-design-patterns</artifactId>
-        <version>1.23.0-SNAPSHOT</version>
+        <version>1.24.0-SNAPSHOT</version>
     </parent>
 
     <dependencies>

eip-message-channel/pom.xml

@@ -30,7 +30,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.23.0-SNAPSHOT</version>
+		<version>1.24.0-SNAPSHOT</version>
 	</parent>
 	<artifactId>eip-message-channel</artifactId>
 	<dependencies>

eip-publish-subscribe/pom.xml

@@ -28,7 +28,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.23.0-SNAPSHOT</version>
+		<version>1.24.0-SNAPSHOT</version>
 	</parent>
 	<artifactId>eip-publish-subscribe</artifactId>
 	<dependencies>

eip-splitter/pom.xml

@@ -31,7 +31,7 @@
     <parent>
         <groupId>com.iluwatar</groupId>
         <artifactId>java-design-patterns</artifactId>
-        <version>1.23.0-SNAPSHOT</version>
+        <version>1.24.0-SNAPSHOT</version>
     </parent>
 
     <dependencies>

eip-wire-tap/pom.xml

@@ -31,7 +31,7 @@
     <parent>
         <groupId>com.iluwatar</groupId>
         <artifactId>java-design-patterns</artifactId>
-        <version>1.23.0-SNAPSHOT</version>
+        <version>1.24.0-SNAPSHOT</version>
     </parent>
 
     <dependencies>

event-aggregator/pom.xml

@@ -28,7 +28,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.23.0-SNAPSHOT</version>
+		<version>1.24.0-SNAPSHOT</version>
 	</parent>
 	<artifactId>event-aggregator</artifactId>
 	<dependencies>

event-asynchronous/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.23.0-SNAPSHOT</version>
+    <version>1.24.0-SNAPSHOT</version>
   </parent>
   <artifactId>event-asynchronous</artifactId>
   <dependencies>

event-driven-architecture/pom.xml

@@ -31,7 +31,7 @@
     <parent>
         <groupId>com.iluwatar</groupId>
         <artifactId>java-design-patterns</artifactId>
-        <version>1.23.0-SNAPSHOT</version>
+        <version>1.24.0-SNAPSHOT</version>
     </parent>
 
     <artifactId>event-driven-architecture</artifactId>

event-queue/pom.xml

@@ -30,7 +30,7 @@
   <parent>
     <artifactId>java-design-patterns</artifactId>
     <groupId>com.iluwatar</groupId>
-    <version>1.23.0-SNAPSHOT</version>
+    <version>1.24.0-SNAPSHOT</version>
   </parent>
   <artifactId>event-queue</artifactId>
   <dependencies>

event-sourcing/pom.xml

@@ -30,7 +30,7 @@
   <parent>
     <artifactId>java-design-patterns</artifactId>
     <groupId>com.iluwatar</groupId>
-    <version>1.23.0-SNAPSHOT</version>
+    <version>1.24.0-SNAPSHOT</version>
   </parent>
   <artifactId>event-sourcing</artifactId>
   <dependencies>

execute-around/README.md

@@ -9,15 +9,18 @@ tags:
 ---
 
 ## Intent
-Execute Around idiom frees the user from certain actions that should always be executed before and after the business 
-method. A good example of this is resource allocation and deallocation leaving the user to specify only what to do with 
-the resource.
+
+Execute Around idiom frees the user from certain actions that should always be executed before and 
+after the business method. A good example of this is resource allocation and deallocation leaving 
+the user to specify only what to do with the resource.
 
 ## Explanation
 
 Real world example
 
-> We need to provide a class that can be used to write text strings to files. To make it easy for the user we let our service class open and close the file automatically, the user only has to specify what is written into which file.       
+> We need to provide a class that can be used to write text strings to files. To make it easy for 
+> the user we let our service class open and close the file automatically, the user only has to 
+> specify what is written into which file.       
 
 In plain words
 
@@ -25,7 +28,9 @@ In plain words
 
 [Stack Overflow](https://stackoverflow.com/questions/341971/what-is-the-execute-around-idiom) says
 
-> Basically it's the pattern where you write a method to do things which are always required, e.g. resource allocation and clean-up, and make the caller pass in "what we want to do with the resource".
+> Basically it's the pattern where you write a method to do things which are always required, e.g. 
+> resource allocation and clean-up, and make the caller pass in "what we want to do with the 
+> resource".
 
 **Programmatic Example**
 
@@ -61,12 +66,15 @@ To utilize the file writer the following code is needed.
 ```
 
 ## Class diagram
+
 ![alt text](./etc/execute-around.png "Execute Around")
 
 ## Applicability
+
 Use the Execute Around idiom when
 
-* you use an API that requires methods to be called in pairs such as open/close or allocate/deallocate.
+* You use an API that requires methods to be called in pairs such as open/close or 
+allocate/deallocate.
 
 ## Credits
 

execute-around/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.23.0-SNAPSHOT</version>
+    <version>1.24.0-SNAPSHOT</version>
   </parent>
   <artifactId>execute-around</artifactId>
   <dependencies>

extension-objects/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <artifactId>java-design-patterns</artifactId>
     <groupId>com.iluwatar</groupId>
-    <version>1.23.0-SNAPSHOT</version>
+    <version>1.24.0-SNAPSHOT</version>
   </parent>
   <modelVersion>4.0.0</modelVersion>
 

facade/README.md

@@ -10,14 +10,18 @@ tags:
 ---
 
 ## Intent
-Provide a unified interface to a set of interfaces in a subsystem.
-Facade defines a higher-level interface that makes the subsystem easier to use.
+
+Provide a unified interface to a set of interfaces in a subsystem. Facade defines a higher-level 
+interface that makes the subsystem easier to use.
 
 ## Explanation
 
 Real world example
 
-> How does a goldmine work? "Well, the miners go down there and dig gold!" you say. That is what you believe because you are using a simple interface that goldmine provides on the outside, internally it has to do a lot of stuff to make it happen. This simple interface to the complex subsystem is a facade.
+> How does a goldmine work? "Well, the miners go down there and dig gold!" you say. That is what you 
+> believe because you are using a simple interface that goldmine provides on the outside, internally 
+> it has to do a lot of stuff to make it happen. This simple interface to the complex subsystem is a 
+> facade.
 
 In plain words
 
@@ -25,11 +29,13 @@ In plain words
 
 Wikipedia says
 
-> A facade is an object that provides a simplified interface to a larger body of code, such as a class library.
+> A facade is an object that provides a simplified interface to a larger body of code, such as a 
+> class library.
 
 **Programmatic Example**
 
-Taking our goldmine example from above. Here we have the dwarven mine worker hierarchy
+Let's take our goldmine example from above. Here we have the dwarven mine worker hierarchy. First
+there's a base class `DwarvenMineWorker`:
 
 ```java
 public abstract class DwarvenMineWorker {
@@ -87,7 +93,12 @@ public abstract class DwarvenMineWorker {
     GO_TO_SLEEP, WAKE_UP, GO_HOME, GO_TO_MINE, WORK
   }
 }
+```
 
+Then we have the concrete dwarf classes `DwarvenTunnelDigger`, `DwarvenGoldDigger` and 
+`DwarvenCartOperator`:
+
+```java
 public class DwarvenTunnelDigger extends DwarvenMineWorker {
 
   private static final Logger LOGGER = LoggerFactory.getLogger(DwarvenTunnelDigger.class);
@@ -135,7 +146,7 @@ public class DwarvenCartOperator extends DwarvenMineWorker {
 
 ```
 
-To operate all these goldmine workers we have the facade
+To operate all these goldmine workers we have the `DwarvenGoldmineFacade`:
 
 ```java
 public class DwarvenGoldmineFacade {
@@ -168,22 +179,27 @@ public class DwarvenGoldmineFacade {
 }
 ```
 
-Now to use the facade
+Now let's use the facade:
 
 ```java
-DwarvenGoldmineFacade facade = new DwarvenGoldmineFacade();
+var facade = new DwarvenGoldmineFacade();
 facade.startNewDay();
+facade.digOutGold();
+facade.endDay();
+```
+
+Program output:
+
+```java
 // Dwarf gold digger wakes up.
 // Dwarf gold digger goes to the mine.
 // Dwarf cart operator wakes up.
 // Dwarf cart operator goes to the mine.
 // Dwarven tunnel digger wakes up.
 // Dwarven tunnel digger goes to the mine.
-facade.digOutGold();
 // Dwarf gold digger digs for gold.
 // Dwarf cart operator moves gold chunks out of the mine.
 // Dwarven tunnel digger creates another promising tunnel.
-facade.endDay();
 // Dwarf gold digger goes home.
 // Dwarf gold digger goes to sleep.
 // Dwarf cart operator goes home.
@@ -193,14 +209,25 @@ facade.endDay();
 ```
 
 ## Class diagram
+
 ![alt text](./etc/facade.urm.png "Facade pattern class diagram")
 
 ## Applicability
+
 Use the Facade pattern when
 
-* you want to provide a simple interface to a complex subsystem. Subsystems often get more complex  as they evolve. Most patterns, when applied, result in more and smaller classes. This makes the subsystem more reusable and easier to customize, but it also becomes harder to use for clients that don't need to customize it. A facade can provide a simple default view of the subsystem that is good enough for most clients. Only clients needing more customizability will need to look beyond the facade.
-* there are many dependencies between clients and the implementation classes of an abstraction. Introduce a facade to decouple the subsystem from clients and other subsystems, thereby promoting subsystem independence and portability.
-* you want to layer your subsystems. Use a facade to define an entry point to each subsystem level. If subsystems are dependent, then you can simplify the dependencies between them by making them communicate with each other solely through their facades.
+* You want to provide a simple interface to a complex subsystem. Subsystems often get more complex 
+as they evolve. Most patterns, when applied, result in more and smaller classes. This makes the 
+subsystem more reusable and easier to customize, but it also becomes harder to use for clients that 
+don't need to customize it. A facade can provide a simple default view of the subsystem that is good 
+enough for most clients. Only clients needing more customization will need to look beyond the 
+facade.
+* There are many dependencies between clients and the implementation classes of an abstraction. 
+Introduce a facade to decouple the subsystem from clients and other subsystems, thereby promoting 
+subsystem independence and portability.
+* You want to layer your subsystems. Use a facade to define an entry point to each subsystem level. 
+If subsystems are dependent, then you can simplify the dependencies between them by making them 
+communicate with each other solely through their facades.
 
 ## Credits
 

facade/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.23.0-SNAPSHOT</version>
+    <version>1.24.0-SNAPSHOT</version>
   </parent>
   <artifactId>facade</artifactId>
   <dependencies>

factory-kit/pom.xml

@@ -30,7 +30,7 @@
     <parent>
         <groupId>com.iluwatar</groupId>
         <artifactId>java-design-patterns</artifactId>
-        <version>1.23.0-SNAPSHOT</version>
+        <version>1.24.0-SNAPSHOT</version>
     </parent>
     <artifactId>factory-kit</artifactId>
     <dependencies>

factory-method/README.md

@@ -10,17 +10,20 @@ tags:
 ---
 
 ## Also known as
+
 Virtual Constructor
 
 ## Intent
-Define an interface for creating an object, but let subclasses
-decide which class to instantiate. Factory Method lets a class defer
-instantiation to subclasses.
+
+Define an interface for creating an object, but let subclasses decide which class to instantiate. 
+Factory Method lets a class defer instantiation to subclasses.
 
 ## Explanation
+
 Real world example
 
-> Blacksmith manufactures weapons. Elves require Elvish weapons and orcs require Orcish weapons. Depending on the customer at hand the right type of blacksmith is summoned.
+> Blacksmith manufactures weapons. Elves require Elvish weapons and orcs require Orcish weapons. 
+> Depending on the customer at hand the right type of blacksmith is summoned.
 
 In plain words
 
@@ -28,11 +31,16 @@ In plain words
 
 Wikipedia says
 
-> In class-based programming, the factory method pattern is a creational pattern that uses factory methods to deal with the problem of creating objects without having to specify the exact class of the object that will be created. This is done by creating objects by calling a factory method—either specified in an interface and implemented by child classes, or implemented in a base class and optionally overridden by derived classes—rather than by calling a constructor.
+> In class-based programming, the factory method pattern is a creational pattern that uses factory 
+> methods to deal with the problem of creating objects without having to specify the exact class of 
+> the object that will be created. This is done by creating objects by calling a factory method 
+> — either specified in an interface and implemented by child classes, or implemented in a base 
+> class and optionally overridden by derived classes—rather than by calling a constructor.
 
  **Programmatic Example**
 
-Taking our blacksmith example above. First of all we have a blacksmith interface and some implementations for it
+Taking our blacksmith example above. First of all we have a `Blacksmith` interface and some 
+implementations for it:
 
 ```java
 public interface Blacksmith {
@@ -52,24 +60,33 @@ public class OrcBlacksmith implements Blacksmith {
 }
 ```
 
-Now as the customers come the correct type of blacksmith is summoned and requested weapons are manufactured
+When the customers come, the correct type of blacksmith is summoned and requested weapons are 
+manufactured:
 
 ```java
 var blacksmith = new ElfBlacksmith();
 blacksmith.manufactureWeapon(WeaponType.SPEAR);
 blacksmith.manufactureWeapon(WeaponType.AXE);
-// Elvish weapons are created
+```
+
+Program output:
+```java
+// Elven spear
+// Elven axe
 ```
 
 ## Class diagram
+
 ![alt text](./etc/factory-method.urm.png "Factory Method pattern class diagram")
 
 ## Applicability
-Use the Factory Method pattern when
 
-* a class can't anticipate the class of objects it must create
-* a class wants its subclasses to specify the objects it creates
-* classes delegate responsibility to one of several helper subclasses, and you want to localize the knowledge of which helper subclass is the delegate
+Use the Factory Method pattern when:
+
+* Class cannot anticipate the class of objects it must create.
+* Class wants its subclasses to specify the objects it creates.
+* Classes delegate responsibility to one of several helper subclasses, and you want to localize the 
+knowledge of which helper subclass is the delegate.
 
 ## Real world examples
 

factory-method/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.23.0-SNAPSHOT</version>
+    <version>1.24.0-SNAPSHOT</version>
   </parent>
   <artifactId>factory-method</artifactId>
   <dependencies>

factory/README.md

@@ -0,0 +1,133 @@
+---
+layout: pattern
+title: Factory
+folder: factory
+permalink: /patterns/factory/
+categories: Creational
+tags:
+ - Gang of Four
+---
+
+## Also known as
+
+* Simple Factory
+* Static Factory Method
+
+## Intent
+
+Providing a static method encapsulated in a class called factory, in order to hide the 
+implementation logic and makes client code focus on usage rather then initialization new objects.
+
+## Explanation
+
+Real world example
+
+> Lets say we have a web application connected to SQLServer, but now we want to switch to Oracle. To 
+> do so without modifying existing source code, we need to implements Simple Factory pattern, in 
+> which a static method can be invoked to create connection to a given database.
+
+Wikipedia says
+
+> Factory is an object for creating other objects – formally a factory is a function or method that 
+> returns objects of a varying prototype or class.
+
+**Programmatic Example**
+
+We have an interface `Car` and two implementations `Ford` and `Ferrari`.
+
+```java
+public interface Car {
+  String getDescription();
+}
+
+public class Ford implements Car {
+
+  static final String DESCRIPTION = "This is Ford.";
+
+  @Override
+  public String getDescription() {
+    return DESCRIPTION;
+  }
+}
+
+public class Ferrari implements Car {
+   
+  static final String DESCRIPTION = "This is Ferrari.";
+
+  @Override
+  public String getDescription() {
+    return DESCRIPTION;
+  }
+}
+```
+
+Enumeration above represents types of cars that we support (`Ford` and `Ferrari`).
+
+```java
+public enum CarType {
+  
+  FORD(Ford::new), 
+  FERRARI(Ferrari::new);
+  
+  private final Supplier<Car> constructor; 
+  
+  CarType(Supplier<Car> constructor) {
+    this.constructor = constructor;
+  }
+  
+  public Supplier<Car> getConstructor() {
+    return this.constructor;
+  }
+}
+```
+Then we have the static method `getCar` to create car objects encapsulated in the factory class 
+`CarSimpleFactory`.
+
+```java
+public class CarsFactory {
+  
+  public static Car getCar(CarType type) {
+    return type.getConstructor().get();
+  }
+}
+```
+
+Now on the client code we can create different types of cars using the factory class.
+
+```java
+var car1 = CarsFactory.getCar(CarType.FORD);
+var car2 = CarsFactory.getCar(CarType.FERRARI);
+LOGGER.info(car1.getDescription());
+LOGGER.info(car2.getDescription());;
+```
+
+Program output:
+
+```java
+This is Ford.
+This Ferrari.
+```
+
+## Class Diagram
+
+![alt text](./etc/factory.urm.png "Factory pattern class diagram")
+
+## Applicability
+
+Use the Simple Factory pattern when you only care about the creation of a object, not how to create 
+and manage it.
+
+Pros
+
+* Allows keeping all objects creation in one place and avoid of spreading 'new' key value across codebase.
+* Allows to writs loosely coupled code. Some of its main advantages include better testability, easy-to-understand code, swappable components, scalability and isolated features.
+
+Cons
+
+* The code becomes more complicated than it should be. 
+
+## Related patterns
+
+* [Factory Method](https://java-design-patterns.com/patterns/factory-method/)
+* [Factory Kit](https://java-design-patterns.com/patterns/factory-kit/)
+* [Abstract Factory](https://java-design-patterns.com/patterns/abstract-factory/)

factory/etc/factory.urm.puml

@@ -0,0 +1,35 @@
+@startuml
+package com.iluwatar.factory {
+  class App {
+    - LOGGER : Logger {static}
+    + App()
+    + main(args : String[]) {static}
+  }
+  interface Car {
+    + getDescription() : String {abstract}
+  }
+  class CarsFactory {
+    + CarsFactory()
+    + getCar(type : CarType) : Car {static}
+  }
+  ~enum CarType {
+    + FERRARI {static}
+    + FORD {static}
+    + valueOf(name : String) : CarType {static}
+    + values() : CarType[] {static}
+  }
+  class Ferrari {
+    ~ DESCRIPTION : String {static}
+    + Ferrari()
+    + getDescription() : String
+  }
+  class Ford {
+    ~ DESCRIPTION : String {static}
+    + Ford()
+    + getDescription() : String
+  }
+}
+CarType ..+ CarsFactory
+Ferrari ..|> Car 
+Ford ..|> Car 
+@enduml

factory/pom.xml

@@ -0,0 +1,43 @@
+<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+ <modelVersion>4.0.0</modelVersion>
+ <parent>
+ <groupId>com.iluwatar</groupId>
+ <artifactId>java-design-patterns</artifactId>
+ <version>1.24.0-SNAPSHOT</version>
+ </parent>
+ <artifactId>factory</artifactId>
+ <dependencies>
+ <dependency>
+  <groupId>org.junit.jupiter</groupId>
+  <artifactId>junit-jupiter-engine</artifactId>
+  <scope>test</scope>
+ </dependency>
+ <dependency>
+ <groupId>junit</groupId>
+  <artifactId>junit</artifactId>
+ </dependency>
+ </dependencies>
+ <build>
+ <plugins>
+  <!-- Maven assembly plugin is invoked with default setting which we have 
+  in parent pom and specifying the class having main method -->
+  <plugin>
+  <groupId>org.apache.maven.plugins</groupId>
+  <artifactId>maven-assembly-plugin</artifactId>
+  <executions>
+   <execution>
+   <configuration>
+    <archive>
+    <manifest>
+     <mainClass>com.iluwatar.factory.App</mainClass>
+    </manifest>
+    </archive>
+   </configuration>
+   </execution>
+  </executions>
+  </plugin>
+ </plugins>
+ </build>
+</project>

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

@@ -0,0 +1,51 @@
+/*
+ * The MIT License
+ * Copyright © 2014-2019 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.factory;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Factory is an object for creating other objects, it providing Providing a static method to 
+ * create and return objects of varying classes, in order to hide the implementation logic 
+ * and makes client code focus on usage rather then objects initialization and management.
+ * 
+ * <p>In this example the CarFactory is the factory class and it provides a static method to 
+ * create different cars.
+ */
+
+public class App {
+  
+  private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
+  
+  /**
+   * Program main entry point.
+   */
+  public static void main(String[] args) {
+    var car1 = CarsFactory.getCar(CarType.FORD);
+    var car2 = CarsFactory.getCar(CarType.FERRARI);
+    LOGGER.info(car1.getDescription());
+    LOGGER.info(car2.getDescription());
+  }
+}

factory/src/main/java/com/iluwatar/factory/Car.java

@@ -0,0 +1,10 @@
+package com.iluwatar.factory;
+
+/**
+ * Car interface.
+ */
+public interface Car {
+  
+  String getDescription();
+  
+}

factory/src/main/java/com/iluwatar/factory/CarType.java

@@ -0,0 +1,22 @@
+package com.iluwatar.factory;
+
+import java.util.function.Supplier;
+
+public enum CarType {
+  
+  /**
+   * Enumeration for different types of cars.
+   */
+  FORD(Ford::new), 
+  FERRARI(Ferrari::new);
+  
+  private final Supplier<Car> constructor; 
+  
+  CarType(Supplier<Car> constructor) {
+    this.constructor = constructor;
+  }
+  
+  public Supplier<Car> getConstructor() {
+    return this.constructor;
+  }
+}

factory/src/main/java/com/iluwatar/factory/CarsFactory.java

@@ -0,0 +1,14 @@
+package com.iluwatar.factory;
+
+/**
+ * Factory of cars.
+ */
+public class CarsFactory {
+  
+  /**
+   * Factory method takes as parameter a car type and initiate the appropriate class.
+   */
+  public static Car getCar(CarType type) {
+    return type.getConstructor().get();
+  }
+}

factory/src/main/java/com/iluwatar/factory/Ferrari.java

@@ -0,0 +1,14 @@
+package com.iluwatar.factory;
+
+/**
+ * Ferrari implementation.
+ */
+public class Ferrari implements Car {
+   
+  static final String DESCRIPTION = "This is Ferrari.";
+
+  @Override
+  public String getDescription() {
+    return DESCRIPTION;
+  }
+}

factory/src/main/java/com/iluwatar/factory/Ford.java

@@ -0,0 +1,14 @@
+package com.iluwatar.factory;
+
+/**
+ * Ford implementation.
+ */
+public class Ford implements Car {
+
+  static final String DESCRIPTION = "This is Ford.";
+
+  @Override
+  public String getDescription() {
+    return DESCRIPTION;
+  }
+}

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

@@ -0,0 +1,14 @@
+package com.iluwatar.factory;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+
+class AppTest {
+
+	@Test
+	void shouldExecuteWithoutExceptions() {
+		assertDoesNotThrow(() -> App.main(new String[]{}));
+	}
+
+}

factory/src/test/java/com/iluwatar/factory/CarsFactoryTest.java

@@ -0,0 +1,15 @@
+package com.iluwatar.factory;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+
+class CarsFactoryTest {
+
+	@Test
+	void shouldReturnFerrariInstance() {
+		final var ferrari = CarsFactory.getCar(CarType.FERRARI);
+		assertTrue(ferrari instanceof Ferrari);
+	}
+
+}

feature-toggle/pom.xml

@@ -29,7 +29,7 @@
     <parent>
         <artifactId>java-design-patterns</artifactId>
         <groupId>com.iluwatar</groupId>
-        <version>1.23.0-SNAPSHOT</version>
+        <version>1.24.0-SNAPSHOT</version>
     </parent>
     <modelVersion>4.0.0</modelVersion>
 

filterer/pom.xml

@@ -29,7 +29,7 @@
     <parent>
         <artifactId>java-design-patterns</artifactId>
         <groupId>com.iluwatar</groupId>
-        <version>1.23.0-SNAPSHOT</version>
+        <version>1.24.0-SNAPSHOT</version>
     </parent>
     <modelVersion>4.0.0</modelVersion>
 

fluentinterface/README.md

@@ -9,23 +9,25 @@ tags:
 ---
 
 ## Intent
-A fluent interface provides an easy-readable, flowing interface, that often mimics a domain specific language. Using 
-this pattern results in code that can be read nearly as human language.
+
+A fluent interface provides an easy-readable, flowing interface, that often mimics a domain specific 
+language. Using this pattern results in code that can be read nearly as human language.
 
 ## Explanation
 
-The Fluent Interface pattern is useful when you want to provide an easy readable, flowing API. Those interfaces tend 
-to mimic domain specific languages, so they can nearly be read as human languages.
+The Fluent Interface pattern is useful when you want to provide an easy readable, flowing API. Those 
+interfaces tend to mimic domain specific languages, so they can nearly be read as human languages.
  
 A fluent interface can be implemented using any of
  
- * Method Chaining - calling a method returns some object on which further methods can be called.
- * Static Factory Methods and Imports
+ * Method chaining - calling a method returns some object on which further methods can be called.
+ * Static factory methods and imports.
  * Named parameters - can be simulated in Java using static factory methods.
 
 Real world example
 
-> We need to select numbers based on different criteria from the list. It's a great chance to utilize fluent interface pattern to provide readable easy-to-use developer experience. 
+> We need to select numbers based on different criteria from the list. It's a great chance to 
+> utilize fluent interface pattern to provide readable easy-to-use developer experience. 
 
 In plain words
 
@@ -33,7 +35,9 @@ In plain words
 
 Wikipedia says
 
-> In software engineering, a fluent interface is an object-oriented API whose design relies extensively on method chaining. Its goal is to increase code legibility by creating a domain-specific language (DSL).
+> In software engineering, a fluent interface is an object-oriented API whose design relies 
+> extensively on method chaining. Its goal is to increase code legibility by creating a 
+> domain-specific language (DSL).
 
 **Programmatic Example**
 
@@ -134,29 +138,35 @@ result is printed afterwards.
         .first(2)
         .last()
         .ifPresent(number -> LOGGER.info("Last amongst first two negatives: {}", number));
-    
-    // The initial list contains: 1, -61, 14, -22, 18, -87, 6, 64, -82, 26, -98, 97, 45, 23, 2, -68.
-    // The first three negative values are: -61, -22, -87.
-    // The last two positive values are: 23, 2.
-    // The first even number is: 14
-    // A string-mapped list of negative numbers contains: String[-61], String[-22], String[-87], String[-82], String[-98], String[-68].
-    // The lazy list contains the last two of the first four positive numbers mapped to Strings: String[18], String[6].
-    // Last amongst first two negatives: -22    
+```
+
+Program output:
+
+```java
+The initial list contains: 1, -61, 14, -22, 18, -87, 6, 64, -82, 26, -98, 97, 45, 23, 2, -68.
+The first three negative values are: -61, -22, -87.
+The last two positive values are: 23, 2.
+The first even number is: 14
+A string-mapped list of negative numbers contains: String[-61], String[-22], String[-87], String[-82], String[-98], String[-68].
+The lazy list contains the last two of the first four positive numbers mapped to Strings: String[18], String[6].
+Last amongst first two negatives: -22    
 ```
 
 ## Class diagram
+
 ![Fluent Interface](./etc/fluentinterface.png "Fluent Interface")
 
 ## Applicability
+
 Use the Fluent Interface pattern when
 
-* You provide an API that would benefit from a DSL-like usage
-* You have objects that are difficult to configure or use
+* You provide an API that would benefit from a DSL-like usage.
+* You have objects that are difficult to configure or use.
 
 ## Known uses
 
 * [Java 8 Stream API](http://www.oracle.com/technetwork/articles/java/ma14-java-se-8-streams-2177646.html)
-* [Google Guava FluentInterable](https://github.com/google/guava/wiki/FunctionalExplained)
+* [Google Guava FluentIterable](https://github.com/google/guava/wiki/FunctionalExplained)
 * [JOOQ](http://www.jooq.org/doc/3.0/manual/getting-started/use-cases/jooq-as-a-standalone-sql-builder/)
 * [Mockito](http://mockito.org/)
 * [Java Hamcrest](http://code.google.com/p/hamcrest/wiki/Tutorial)

fluentinterface/pom.xml

@@ -29,7 +29,7 @@
     <parent>
         <artifactId>java-design-patterns</artifactId>
         <groupId>com.iluwatar</groupId>
-        <version>1.23.0-SNAPSHOT</version>
+        <version>1.24.0-SNAPSHOT</version>
     </parent>
     <modelVersion>4.0.0</modelVersion>
 

fluentinterface/src/main/java/com/iluwatar/fluentinterface/app/App.java

@@ -23,8 +23,6 @@
 
 package com.iluwatar.fluentinterface.app;
 
-import static java.lang.String.valueOf;
-
 import com.iluwatar.fluentinterface.fluentiterable.FluentIterable;
 import com.iluwatar.fluentinterface.fluentiterable.lazy.LazyFluentIterable;
 import com.iluwatar.fluentinterface.fluentiterable.simple.SimpleFluentIterable;

fluentinterface/src/main/java/com/iluwatar/fluentinterface/fluentiterable/lazy/LazyFluentIterable.java

@@ -70,7 +70,7 @@ public class LazyFluentIterable<E> implements FluentIterable<E> {
     return new LazyFluentIterable<>() {
       @Override
       public Iterator<E> iterator() {
-        return new DecoratingIterator<E>(iterable.iterator()) {
+        return new DecoratingIterator<>(iterable.iterator()) {
           @Override
           public E computeNext() {
             while (fromIterator.hasNext()) {
@@ -107,10 +107,10 @@ public class LazyFluentIterable<E> implements FluentIterable<E> {
    */
   @Override
   public FluentIterable<E> first(int count) {
-    return new LazyFluentIterable<E>() {
+    return new LazyFluentIterable<>() {
       @Override
       public Iterator<E> iterator() {
-        return new DecoratingIterator<E>(iterable.iterator()) {
+        return new DecoratingIterator<>(iterable.iterator()) {
           int currentIndex;
 
           @Override
@@ -149,10 +149,10 @@ public class LazyFluentIterable<E> implements FluentIterable<E> {
    */
   @Override
   public FluentIterable<E> last(int count) {
-    return new LazyFluentIterable<E>() {
+    return new LazyFluentIterable<>() {
       @Override
       public Iterator<E> iterator() {
-        return new DecoratingIterator<E>(iterable.iterator()) {
+        return new DecoratingIterator<>(iterable.iterator()) {
           private int stopIndex;
           private int totalElementsCount;
           private List<E> list;
@@ -194,10 +194,10 @@ public class LazyFluentIterable<E> implements FluentIterable<E> {
    */
   @Override
   public <T> FluentIterable<T> map(Function<? super E, T> function) {
-    return new LazyFluentIterable<T>() {
+    return new LazyFluentIterable<>() {
       @Override
       public Iterator<T> iterator() {
-        return new DecoratingIterator<T>(null) {
+        return new DecoratingIterator<>(null) {
           final Iterator<E> oldTypeIterator = iterable.iterator();
 
           @Override
@@ -226,7 +226,7 @@ public class LazyFluentIterable<E> implements FluentIterable<E> {
 
   @Override
   public Iterator<E> iterator() {
-    return new DecoratingIterator<E>(iterable.iterator()) {
+    return new DecoratingIterator<>(iterable.iterator()) {
       @Override
       public E computeNext() {
         return fromIterator.hasNext() ? fromIterator.next() : null;

flux/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.23.0-SNAPSHOT</version>
+    <version>1.24.0-SNAPSHOT</version>
   </parent>
   <artifactId>flux</artifactId>
   <dependencies>