Merge pull request #281 from ankurkaushal/master

Reformat according to google style guide

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

@@ -3,21 +3,18 @@ package com.iluwatar.abstractfactory;
 
 /**
  * 
- * The Abstract Factory pattern provides a way to encapsulate a group of individual 
+ * The Abstract Factory pattern provides a way to encapsulate a group of individual factories that
- * factories that have a common theme without specifying their concrete classes. In 
+ * have a common theme without specifying their concrete classes. In normal usage, the client
- * normal usage, the client software creates a concrete implementation of the abstract 
+ * software creates a concrete implementation of the abstract factory and then uses the generic
- * factory and then uses the generic interface of the factory to create the concrete 
+ * interface of the factory to create the concrete objects that are part of the theme. The client
- * objects that are part of the theme. The client does not know (or care) which 
+ * does not know (or care) which concrete objects it gets from each of these internal factories,
- * concrete objects it gets from each of these internal factories, since it uses only 
+ * since it uses only the generic interfaces of their products. This pattern separates the details
- * the generic interfaces of their products. This pattern separates the details of 
+ * of implementation of a set of objects from their general usage and relies on object composition,
- * implementation of a set of objects from their general usage and relies on object 
+ * as object creation is implemented in methods exposed in the factory interface.
- * composition, as object creation is implemented in methods exposed in the factory 
- * interface.
  * <p>
- * The essence of the Abstract Factory pattern is a factory interface
+ * The essence of the Abstract Factory pattern is a factory interface ({@link KingdomFactory}) and
- * ({@link KingdomFactory}) and its implementations ({@link ElfKingdomFactory},
+ * its implementations ({@link ElfKingdomFactory}, {@link OrcKingdomFactory}). The example uses both
- * {@link OrcKingdomFactory}). The example uses both concrete implementations to 
+ * concrete implementations to create a king, a castle and an army.
- * create a king, a castle and an army.
  * 
  */
 public class App {
@@ -28,6 +25,7 @@ public class App {
 
   /**
    * Creates kingdom
+   * 
    * @param factory
    */
   public void createKingdom(final KingdomFactory factory) {

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

@@ -7,7 +7,7 @@ package com.iluwatar.abstractfactory;
  */
 public class OrcKing implements King {
 
-static final String DESCRIPTION = "This is the Orc king!";
+  static final String DESCRIPTION = "This is the Orc king!";
 
   @Override
   public String getDescription() {

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

@@ -18,5 +18,4 @@ public class OrcKingdomFactory implements KingdomFactory {
   public Army createArmy() {
     return new OrcArmy();
   }
-
 }

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

@@ -1,4 +1,5 @@
 package com.iluwatar.abstractfactory;
+
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
 

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

@@ -2,26 +2,25 @@ package com.iluwatar.adapter;
 
 /**
  *
- * An adapter helps two incompatible interfaces to work together. This is the real 
+ * An adapter helps two incompatible interfaces to work together. This is the real world definition
- * world definition for an adapter. Interfaces may be incompatible but the inner 
+ * for an adapter. Interfaces may be incompatible but the inner functionality should suit the need.
- * functionality should suit the need. The Adapter design pattern allows otherwise 
+ * The Adapter design pattern allows otherwise incompatible classes to work together by converting
- * incompatible classes to work together by converting the interface of one class 
+ * the interface of one class into an interface expected by the clients.
- * into an interface expected by the clients.
  * <p>
- * There are two variations of the Adapter pattern: The class adapter implements
+ * There are two variations of the Adapter pattern: The class adapter implements the adaptee's
- * the adaptee's interface whereas the object adapter uses composition to
+ * interface whereas the object adapter uses composition to contain the adaptee in the adapter
- * contain the adaptee in the adapter object. This example uses the object
+ * object. This example uses the object adapter approach.
- * adapter approach.
  * <p>
- * The Adapter ({@link GnomeEngineer}) converts the interface of the target class
+ * The Adapter ({@link GnomeEngineer}) converts the interface of the target class (
- * ({@link GoblinGlider}) into a suitable one expected by the client
+ * {@link GoblinGlider}) into a suitable one expected by the client ({@link GnomeEngineeringManager}
- * ({@link GnomeEngineeringManager}).
+ * ).
  * 
  */
 public class App {
 
   /**
    * Program entry point
+   * 
    * @param args command line args
    */
   public static void main(String[] args) {

adapter/src/main/java/com/iluwatar/adapter/Engineer.java

@@ -8,5 +8,4 @@ package com.iluwatar.adapter;
 public interface Engineer {
 
   void operateDevice();
-
 }

adapter/src/main/java/com/iluwatar/adapter/GnomeEngineer.java

@@ -2,8 +2,8 @@ package com.iluwatar.adapter;
 
 /**
  * 
- * Adapter class. Adapts the interface of the device ({@link GoblinGlider}) into
+ * Adapter class. Adapts the interface of the device ({@link GoblinGlider}) into {@link Engineer}
- * {@link Engineer} interface expected by the client ({@link GnomeEngineeringManager}).
+ * interface expected by the client ({@link GnomeEngineeringManager}).
  * 
  */
 public class GnomeEngineer implements Engineer {
@@ -20,5 +20,4 @@ public class GnomeEngineer implements Engineer {
     glider.gainSpeed();
     glider.takeOff();
   }
-
 }

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

@@ -4,23 +4,24 @@ import java.util.concurrent.Callable;
 
 /**
  * This application demonstrates the async method invocation pattern. Key parts of the pattern are
- * <code>AsyncResult</code> which is an intermediate container for an asynchronously evaluated value,
+ * <code>AsyncResult</code> which is an intermediate container for an asynchronously evaluated
- * <code>AsyncCallback</code> which can be provided to be executed on task completion and
+ * value, <code>AsyncCallback</code> which can be provided to be executed on task completion and
  * <code>AsyncExecutor</code> that manages the execution of the async tasks.
  * <p>
- * The main method shows example flow of async invocations. The main thread starts multiple tasks with
+ * The main method shows example flow of async invocations. The main thread starts multiple tasks
- * variable durations and then continues its own work. When the main thread has done it's job it collects
+ * with variable durations and then continues its own work. When the main thread has done it's job
- * the results of the async tasks. Two of the tasks are handled with callbacks, meaning the callbacks are
+ * it collects the results of the async tasks. Two of the tasks are handled with callbacks, meaning
- * executed immediately when the tasks complete.
+ * the callbacks are executed immediately when the tasks complete.
  * <p>
- * Noteworthy difference of thread usage between the async results and callbacks is that the async results
+ * Noteworthy difference of thread usage between the async results and callbacks is that the async
- * are collected in the main thread but the callbacks are executed within the worker threads. This should be
+ * results are collected in the main thread but the callbacks are executed within the worker
- * noted when working with thread pools.
+ * threads. This should be noted when working with thread pools.
  * <p>
- * Java provides its own implementations of async method invocation pattern. FutureTask, CompletableFuture
+ * Java provides its own implementations of async method invocation pattern. FutureTask,
- * and ExecutorService are the real world implementations of this pattern. But due to the nature of parallel
+ * CompletableFuture and ExecutorService are the real world implementations of this pattern. But due
- * programming, the implementations are not trivial. This example does not take all possible scenarios into
+ * to the nature of parallel programming, the implementations are not trivial. This example does not
- * account but rather provides a simple version that helps to understand the pattern.
+ * take all possible scenarios into account but rather provides a simple version that helps to
+ * understand the pattern.
  *
  * @see AsyncResult
  * @see AsyncCallback
@@ -40,8 +41,10 @@ public class App {
     AsyncResult<Integer> asyncResult1 = executor.startProcess(lazyval(10, 500));
     AsyncResult<String> asyncResult2 = executor.startProcess(lazyval("test", 300));
     AsyncResult<Long> asyncResult3 = executor.startProcess(lazyval(50L, 700));
-		AsyncResult<Integer> asyncResult4 = executor.startProcess(lazyval(20, 400), callback("Callback result 4"));
+    AsyncResult<Integer> asyncResult4 =
-		AsyncResult<String> asyncResult5 = executor.startProcess(lazyval("callback", 600), callback("Callback result 5"));
+        executor.startProcess(lazyval(20, 400), callback("Callback result 4"));
+    AsyncResult<String> asyncResult5 =
+        executor.startProcess(lazyval("callback", 600), callback("Callback result 5"));
 
     // emulate processing in the current thread while async tasks are running in their own threads
     Thread.sleep(350); // Oh boy I'm working hard here

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

@@ -18,5 +18,4 @@ public interface AsyncCallback<T> {
    * @param ex empty value if execution succeeds, some exception if executions fails
    */
   void onComplete(T value, Optional<Exception> ex);
-
 }

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

@@ -38,5 +38,4 @@ public interface AsyncExecutor {
    * @throws InterruptedException if the execution is interrupted
    */
   <T> T endProcess(AsyncResult<T> asyncResult) throws ExecutionException, InterruptedException;
-
 }

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

@@ -34,7 +34,8 @@ public class ThreadAsyncExecutor implements AsyncExecutor {
   }
 
   @Override
-	public <T> T endProcess(AsyncResult<T> asyncResult) throws ExecutionException, InterruptedException {
+  public <T> T endProcess(AsyncResult<T> asyncResult) throws ExecutionException,
+      InterruptedException {
     if (asyncResult.isCompleted()) {
       return asyncResult.getValue();
     } else {
@@ -44,8 +45,8 @@ public class ThreadAsyncExecutor implements AsyncExecutor {
   }
 
   /**
-	 * Simple implementation of async result that allows completing it successfully with a value
+   * Simple implementation of async result that allows completing it successfully with a value or
-	 * or exceptionally with an exception. A really simplified version from its real life cousins
+   * exceptionally with an exception. A really simplified version from its real life cousins
    * FutureTask and CompletableFuture.
    *
    * @see java.util.concurrent.FutureTask
@@ -70,8 +71,8 @@ public class ThreadAsyncExecutor implements AsyncExecutor {
     }
 
     /**
-		 * Sets the value from successful execution and executes callback if available. Notifies
+     * Sets the value from successful execution and executes callback if available. Notifies any
-		 * any thread waiting for completion.
+     * thread waiting for completion.
      *
      * @param value value of the evaluated task
      */
@@ -85,8 +86,8 @@ public class ThreadAsyncExecutor implements AsyncExecutor {
     }
 
     /**
-		 * Sets the exception from failed execution and executes callback if available. Notifies
+     * Sets the exception from failed execution and executes callback if available. Notifies any
-		 * any thread waiting for completion.
+     * thread waiting for completion.
      *
      * @param exception exception of the failed task
      */

async-method-invocation/src/test/java/com/iluwatar/async/method/invocation/AppTest.java

@@ -14,5 +14,4 @@ public class AppTest {
     String[] args = {};
     App.main(args);
   }
-
 }

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

@@ -2,41 +2,38 @@ package com.iluwatar.bridge;
 
 /**
  * 
- * The Bridge pattern can also be thought of as two layers of abstraction. With Bridge, 
+ * The Bridge pattern can also be thought of as two layers of abstraction. With Bridge, you can
- * you can decouple an abstraction from its implementation so that the two can vary independently.
+ * decouple an abstraction from its implementation so that the two can vary independently.
  * <p>
- * In Bridge pattern both abstraction ({@link MagicWeapon}) and implementation
+ * In Bridge pattern both abstraction ({@link MagicWeapon}) and implementation (
- * ({@link MagicWeaponImpl}) have their own class hierarchies. The interface of the
+ * {@link MagicWeaponImpl}) have their own class hierarchies. The interface of the implementations
- * implementations can be changed without affecting the clients.
+ * can be changed without affecting the clients.
  * 
  */
 public class App {
 
   /**
    * Program entry point
+   * 
    * @param args command line args
    */
   public static void main(String[] args) {
-		BlindingMagicWeapon blindingMagicWeapon = new BlindingMagicWeapon(
+    BlindingMagicWeapon blindingMagicWeapon = new BlindingMagicWeapon(new Excalibur());
-				new Excalibur());
     blindingMagicWeapon.wield();
     blindingMagicWeapon.blind();
     blindingMagicWeapon.swing();
     blindingMagicWeapon.unwield();
 
-		FlyingMagicWeapon flyingMagicWeapon = new FlyingMagicWeapon(
+    FlyingMagicWeapon flyingMagicWeapon = new FlyingMagicWeapon(new Mjollnir());
-				new Mjollnir());
     flyingMagicWeapon.wield();
     flyingMagicWeapon.fly();
     flyingMagicWeapon.swing();
     flyingMagicWeapon.unwield();
 
-		SoulEatingMagicWeapon soulEatingMagicWeapon = new SoulEatingMagicWeapon(
+    SoulEatingMagicWeapon soulEatingMagicWeapon = new SoulEatingMagicWeapon(new Stormbringer());
-				new Stormbringer());
     soulEatingMagicWeapon.wield();
     soulEatingMagicWeapon.swing();
     soulEatingMagicWeapon.eatSoul();
     soulEatingMagicWeapon.unwield();
-
   }
 }

bridge/src/main/java/com/iluwatar/bridge/BlindingMagicWeapon.java

@@ -34,5 +34,4 @@ public class BlindingMagicWeapon extends MagicWeapon {
   public void blind() {
     getImp().blindImp();
   }
-
 }

bridge/src/main/java/com/iluwatar/bridge/Excalibur.java

@@ -24,8 +24,6 @@ public class Excalibur extends BlindingMagicWeaponImpl {
 
   @Override
   public void blindImp() {
-		System.out
+    System.out.println("bright light streams from Excalibur blinding the enemy");
-				.println("bright light streams from Excalibur blinding the enemy");
   }
-
 }

bridge/src/main/java/com/iluwatar/bridge/MagicWeapon.java

@@ -22,5 +22,4 @@ public abstract class MagicWeapon {
   public MagicWeaponImpl getImp() {
     return imp;
   }
-
 }

bridge/src/main/java/com/iluwatar/bridge/Mjollnir.java

@@ -24,8 +24,6 @@ public class Mjollnir extends FlyingMagicWeaponImpl {
 
   @Override
   public void flyImp() {
-		System.out
+    System.out.println("Mjollnir hits the enemy in the air and returns back to the owner's hand");
-				.println("Mjollnir hits the enemy in the air and returns back to the owner's hand");
   }
-
 }

bridge/src/main/java/com/iluwatar/bridge/Stormbringer.java

@@ -26,5 +26,4 @@ public class Stormbringer extends SoulEatingMagicWeaponImpl {
   public void eatSoulImp() {
     System.out.println("Stormbringer devours the enemy's soul");
   }
-
 }

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

@@ -1,54 +1,54 @@
 package com.iluwatar.builder;
 
-import com.iluwatar. builder.Hero.HeroBuilder;
+import com.iluwatar.builder.Hero.HeroBuilder;
 
 /**
  * 
- * The intention of the Builder pattern is to find a solution to the telescoping 
+ * The intention of the Builder pattern is to find a solution to the telescoping constructor
- * constructor anti-pattern. The telescoping constructor anti-pattern occurs when the 
+ * anti-pattern. The telescoping constructor anti-pattern occurs when the increase of object
- * increase of object constructor parameter combination leads to an exponential list 
+ * constructor parameter combination leads to an exponential list of constructors. Instead of using
- * of constructors. Instead of using numerous constructors, the builder pattern uses 
+ * numerous constructors, the builder pattern uses another object, a builder, that receives each
- * another object, a builder, that receives each initialization parameter step by step 
+ * initialization parameter step by step and then returns the resulting constructed object at once.
- * and then returns the resulting constructed object at once.
  * <p>
- * The Builder pattern has another benefit. It can be used for objects that contain 
+ * The Builder pattern has another benefit. It can be used for objects that contain flat data (html
- * flat data (html code, SQL query, X.509 certificate...), that is to say, data that 
+ * code, SQL query, X.509 certificate...), that is to say, data that can't be easily edited. This
- * can't be easily edited. This type of data cannot be edited step by step and must 
+ * type of data cannot be edited step by step and must be edited at once. The best way to construct
- * be edited at once. The best way to construct such an object is to use a builder 
+ * such an object is to use a builder class.
- * class.
  * <p>
- * In this example we have the Builder pattern variation as described by Joshua Bloch in
+ * In this example we have the Builder pattern variation as described by Joshua Bloch in Effective
- * Effective Java 2nd Edition.
+ * Java 2nd Edition.
  * <p>
- * We want to build {@link Hero} objects, but its construction is complex because of the
+ * We want to build {@link Hero} objects, but its construction is complex because of the many
- * many parameters needed. To aid the user we introduce {@link HeroBuilder} class.
+ * parameters needed. To aid the user we introduce {@link HeroBuilder} class. {@link HeroBuilder}
- * {@link HeroBuilder} takes the minimum parameters to build {@link Hero} object in its
+ * takes the minimum parameters to build {@link Hero} object in its constructor. After that
- * constructor. After that additional configuration for the {@link Hero} object can be
+ * additional configuration for the {@link Hero} object can be done using the fluent
- * done using the fluent {@link HeroBuilder} interface. When configuration is ready the
+ * {@link HeroBuilder} interface. When configuration is ready the build method is called to receive
- * build method is called to receive the final {@link Hero} object.
+ * the final {@link Hero} object.
  * 
  */
 public class App {
 
   /**
    * Program entry point
+   * 
    * @param args command line args
    */
   public static void main(String[] args) {
 
-		Hero mage = new HeroBuilder(Profession.MAGE, "Riobard")
+    Hero mage =
-				.withHairColor(HairColor.BLACK).withWeapon(Weapon.DAGGER)
+        new HeroBuilder(Profession.MAGE, "Riobard").withHairColor(HairColor.BLACK)
-				.build();
+            .withWeapon(Weapon.DAGGER).build();
     System.out.println(mage);
 
-		Hero warrior = new HeroBuilder(Profession.WARRIOR, "Amberjill")
+    Hero warrior =
-				.withHairColor(HairColor.BLOND)
+        new HeroBuilder(Profession.WARRIOR, "Amberjill").withHairColor(HairColor.BLOND)
-				.withHairType(HairType.LONG_CURLY).withArmor(Armor.CHAIN_MAIL)
+            .withHairType(HairType.LONG_CURLY).withArmor(Armor.CHAIN_MAIL).withWeapon(Weapon.SWORD)
-				.withWeapon(Weapon.SWORD).build();
+            .build();
     System.out.println(warrior);
 
-		Hero thief = new HeroBuilder(Profession.THIEF, "Desmond")
+    Hero thief =
-				.withHairType(HairType.BALD).withWeapon(Weapon.BOW).build();
+        new HeroBuilder(Profession.THIEF, "Desmond").withHairType(HairType.BALD)
+            .withWeapon(Weapon.BOW).build();
     System.out.println(thief);
 
   }

builder/src/main/java/com/iluwatar/builder/HairType.java

@@ -7,7 +7,8 @@ package com.iluwatar.builder;
  */
 public enum HairType {
 
-	BALD("bald"), SHORT("short"), CURLY("curly"), LONG_STRAIGHT("long straight"), LONG_CURLY("long curly");
+  BALD("bald"), SHORT("short"), CURLY("curly"), LONG_STRAIGHT("long straight"), LONG_CURLY(
+      "long curly");
 
   private String title;
 

builder/src/main/java/com/iluwatar/builder/Hero.java

@@ -95,8 +95,7 @@ public class Hero {
 
     public HeroBuilder(Profession profession, String name) {
       if (profession == null || name == null) {
-				throw new IllegalArgumentException(
+        throw new IllegalArgumentException("profession and name can not be null");
-						"profession and name can not be null");
       }
       this.profession = profession;
       this.name = name;

builder/src/main/java/com/iluwatar/builder/Profession.java

@@ -13,5 +13,4 @@ public enum Profession {
   public String toString() {
     return name().toLowerCase();
   }
-
 }

builder/src/main/java/com/iluwatar/builder/Weapon.java

@@ -13,5 +13,4 @@ public enum Weapon {
   public String toString() {
     return name().toLowerCase();
   }
-
 }

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

@@ -2,7 +2,7 @@ package com.iluwatar.builder;
 
 import org.junit.Test;
 
-import com.iluwatar. builder.App;
+import com.iluwatar.builder.App;
 
 /**
  * 

business-delegate/src/main/java/com/iluwatar/business/delegate/App.java

@@ -2,23 +2,25 @@ package com.iluwatar.business.delegate;
 
 /**
  * 
- * The Business Delegate pattern adds an abstraction layer between the presentation and business tiers.
+ * The Business Delegate pattern adds an abstraction layer between the presentation and business
- * By using the pattern we gain loose coupling between the tiers. The Business Delegate encapsulates
+ * tiers. By using the pattern we gain loose coupling between the tiers. The Business Delegate
- * knowledge about how to locate, connect to, and interact with the business objects that make up
+ * encapsulates knowledge about how to locate, connect to, and interact with the business objects
- * the application.
+ * that make up the application.
  * <p>
- * Some of the services the Business Delegate uses are instantiated directly, and some can be retrieved
+ * Some of the services the Business Delegate uses are instantiated directly, and some can be
- * through service lookups. The Business Delegate itself may contain business logic too potentially tying
+ * retrieved through service lookups. The Business Delegate itself may contain business logic too
- * together multiple service calls, exception handling, retrying etc.
+ * potentially tying together multiple service calls, exception handling, retrying etc.
  * <p>
- * In this example the client ({@link Client}) utilizes a business delegate ({@link BusinessDelegate}) to execute a task.
+ * In this example the client ({@link Client}) utilizes a business delegate (
- * The Business Delegate then selects the appropriate service and makes the service call.
+ * {@link BusinessDelegate}) to execute a task. The Business Delegate then selects the appropriate
+ * service and makes the service call.
  *
  */
 public class App {
 
   /**
    * Program entry point
+   * 
    * @param args command line args
    */
   public static void main(String[] args) {

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

@@ -2,8 +2,9 @@ package com.iluwatar.callback;
 
 /**
  * 
- * Callback pattern is more native for functional languages where functions are treated as first-class citizens.
+ * Callback pattern is more native for functional languages where functions are treated as
- * Prior to Java 8 callbacks can be simulated using simple (alike command) interfaces.
+ * first-class citizens. Prior to Java 8 callbacks can be simulated using simple (alike command)
+ * interfaces.
  * 
  */
 public class App {

callback/src/main/java/com/iluwatar/callback/SimpleTask.java

@@ -11,5 +11,4 @@ public class SimpleTask extends Task {
   public void execute() {
     System.out.println("Perform some important activity and after call the callback method.");
   }
-
 }

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

@@ -5,8 +5,8 @@ import org.junit.Test;
 import static org.junit.Assert.assertEquals;
 
 /**
- * Add a field as a counter. Every time the callback method is called increment this
+ * Add a field as a counter. Every time the callback method is called increment this field. Unit
- * field. Unit test checks that the field is being incremented.
+ * test checks that the field is being incremented.
  *
  * Could be done with mock objects as well where the call method call is verified.
  */

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

@@ -2,30 +2,29 @@ package com.iluwatar.chain;
 
 /**
  * 
- * The Chain of Responsibility pattern is a design pattern consisting of command 
+ * The Chain of Responsibility pattern is a design pattern consisting of command objects and a
- * objects and a series of processing objects. Each processing object contains 
+ * series of processing objects. Each processing object contains logic that defines the types of
- * logic that defines the types of command objects that it can handle; the rest are 
+ * command objects that it can handle; the rest are passed to the next processing object in the
- * passed to the next processing object in the chain. A mechanism also exists for 
+ * chain. A mechanism also exists for adding new processing objects to the end of this chain.
- * adding new processing objects to the end of this chain.
  * <p>
- * In this example we organize the request handlers ({@link RequestHandler}) into a
+ * In this example we organize the request handlers ({@link RequestHandler}) into a chain where each
- * chain where each handler has a chance to act on the request on its turn. Here
+ * handler has a chance to act on the request on its turn. Here the king ({@link OrcKing}) makes
- * the king ({@link OrcKing}) makes requests and the military orcs ({@link OrcCommander}, 
+ * requests and the military orcs ({@link OrcCommander}, {@link OrcOfficer}, {@link OrcSoldier})
- * {@link OrcOfficer}, {@link OrcSoldier}) form the handler chain.
+ * form the handler chain.
  * 
  */
 public class App {
 
   /**
    * Program entry point
+   * 
    * @param args command line args
    */
   public static void main(String[] args) {
 
     OrcKing king = new OrcKing();
     king.makeRequest(new Request(RequestType.DEFEND_CASTLE, "defend castle"));
-		king.makeRequest(new Request(RequestType.TORTURE_PRISONER,
+    king.makeRequest(new Request(RequestType.TORTURE_PRISONER, "torture prisoner"));
-				"torture prisoner"));
     king.makeRequest(new Request(RequestType.COLLECT_TAX, "collect tax"));
 
   }

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

@@ -2,21 +2,22 @@ package com.iluwatar.command;
 
 /**
  * 
- * The Command pattern is a behavioral design pattern in which an object is used to encapsulate all information 
+ * The Command pattern is a behavioral design pattern in which an object is used to encapsulate all
- * needed to perform an action or trigger an event at a later time. This information includes the method name, 
+ * information needed to perform an action or trigger an event at a later time. This information
- * the object that owns the method and values for the method parameters.
+ * includes the method name, the object that owns the method and values for the method parameters.
  * <p>
- * Four terms always associated with the command pattern are command, receiver, invoker and client. A command 
+ * Four terms always associated with the command pattern are command, receiver, invoker and client.
- * object (spell) knows about the receiver (target) and invokes a method of the receiver. Values for parameters of 
+ * A command object (spell) knows about the receiver (target) and invokes a method of the receiver.
- * the receiver method are stored in the command. The receiver then does the work. An invoker object (wizard) 
+ * Values for parameters of the receiver method are stored in the command. The receiver then does
- * knows how to execute a command, and optionally does bookkeeping about the command execution. The invoker 
+ * the work. An invoker object (wizard) knows how to execute a command, and optionally does
- * does not know anything about a concrete command, it knows only about command interface. Both an invoker object 
+ * bookkeeping about the command execution. The invoker does not know anything about a concrete
- * and several command objects are held by a client object (app). The client decides which commands to execute at 
+ * command, it knows only about command interface. Both an invoker object and several command
- * which points. To execute a command, it passes the command object to the invoker object.
+ * objects are held by a client object (app). The client decides which commands to execute at which
+ * points. To execute a command, it passes the command object to the invoker object.
  * <p>
- * In other words, in this example the wizard casts spells on the goblin. The wizard keeps track of the previous
+ * In other words, in this example the wizard casts spells on the goblin. The wizard keeps track of
- * spells cast, so it is easy to undo them. In addition, the wizard keeps track of the spells undone, so they
+ * the previous spells cast, so it is easy to undo them. In addition, the wizard keeps track of the
- * can be redone.
+ * spells undone, so they can be redone.
  * 
  * 
  */
@@ -24,6 +25,7 @@ public class App {
 
   /**
    * Program entry point
+   * 
    * @param args command line args
    */
   public static void main(String[] args) {

command/src/main/java/com/iluwatar/command/Target.java

@@ -31,8 +31,8 @@ public abstract class Target {
   public abstract String toString();
 
   public void printStatus() {
-		System.out.println(String.format("%s, [size=%s] [visibility=%s]", this,
+    System.out.println(String.format("%s, [size=%s] [visibility=%s]", this, getSize(),
-				getSize(), getVisibility()));
+        getVisibility()));
     System.out.println();
   }
 }

command/src/main/java/com/iluwatar/command/Wizard.java

@@ -13,8 +13,7 @@ public class Wizard {
   private Deque<Command> undoStack = new LinkedList<>();
   private Deque<Command> redoStack = new LinkedList<>();
 
-	public Wizard() {
+  public Wizard() {}
-	}
 
   public void castSpell(Command command, Target target) {
     System.out.println(this + " casts " + command + " at " + target);

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

@@ -1,20 +1,21 @@
 package com.iluwatar.composite;
 
 /**
- * The Composite pattern is a partitioning design pattern. The Composite pattern 
+ * The Composite pattern is a partitioning design pattern. The Composite pattern describes that a
- * describes that a group of objects is to be treated in the same way as a single 
+ * group of objects is to be treated in the same way as a single instance of an object. The intent
- * instance of an object. The intent of a composite is to "compose" objects into 
+ * of a composite is to "compose" objects into tree structures to represent part-whole hierarchies.
- * tree structures to represent part-whole hierarchies. Implementing the Composite 
+ * Implementing the Composite pattern lets clients treat individual objects and compositions
- * pattern lets clients treat individual objects and compositions uniformly.
+ * uniformly.
  * <p>
- * In this example we have sentences composed of words composed of letters. All of
+ * In this example we have sentences composed of words composed of letters. All of the objects can
- * the objects can be treated through the same interface ({@link LetterComposite}).
+ * be treated through the same interface ({@link LetterComposite}).
  * 
  */
 public class App {
 
   /**
    * Program entry point
+   * 
    * @param args command line args
    */
   public static void main(String[] args) {

composite/src/main/java/com/iluwatar/composite/Letter.java

@@ -22,5 +22,4 @@ public class Letter extends LetterComposite {
   protected void printThisAfter() {
     // nop
   }
-
 }

composite/src/main/java/com/iluwatar/composite/Messenger.java

@@ -15,20 +15,19 @@ public class Messenger {
 
     List<Word> words = new ArrayList<Word>();
 
-		words.add(new Word(Arrays.asList(new Letter('W'), new Letter('h'),
+    words.add(new Word(Arrays.asList(new Letter('W'), new Letter('h'), new Letter('e'), new Letter(
-				new Letter('e'), new Letter('r'), new Letter('e'))));
+        'r'), new Letter('e'))));
-		words.add(new Word(Arrays.asList(new Letter('t'), new Letter('h'),
+    words.add(new Word(Arrays.asList(new Letter('t'), new Letter('h'), new Letter('e'), new Letter(
-				new Letter('e'), new Letter('r'), new Letter('e'))));
+        'r'), new Letter('e'))));
     words.add(new Word(Arrays.asList(new Letter('i'), new Letter('s'))));
     words.add(new Word(Arrays.asList(new Letter('a'))));
-		words.add(new Word(Arrays.asList(new Letter('w'), new Letter('h'),
+    words.add(new Word(Arrays.asList(new Letter('w'), new Letter('h'), new Letter('i'), new Letter(
-				new Letter('i'), new Letter('p'))));
+        'p'))));
-		words.add(new Word(Arrays.asList(new Letter('t'), new Letter('h'),
+    words.add(new Word(Arrays.asList(new Letter('t'), new Letter('h'), new Letter('e'), new Letter(
-				new Letter('e'), new Letter('r'), new Letter('e'))));
+        'r'), new Letter('e'))));
     words.add(new Word(Arrays.asList(new Letter('i'), new Letter('s'))));
     words.add(new Word(Arrays.asList(new Letter('a'))));
-		words.add(new Word(Arrays.asList(new Letter('w'), new Letter('a'),
+    words.add(new Word(Arrays.asList(new Letter('w'), new Letter('a'), new Letter('y'))));
-				new Letter('y'))));
 
     return new Sentence(words);
 
@@ -38,18 +37,18 @@ public class Messenger {
 
     List<Word> words = new ArrayList<Word>();
 
-		words.add(new Word(Arrays.asList(new Letter('M'), new Letter('u'),
+    words.add(new Word(Arrays.asList(new Letter('M'), new Letter('u'), new Letter('c'), new Letter(
-				new Letter('c'), new Letter('h'))));
+        'h'))));
-		words.add(new Word(Arrays.asList(new Letter('w'), new Letter('i'),
+    words.add(new Word(Arrays.asList(new Letter('w'), new Letter('i'), new Letter('n'), new Letter(
-				new Letter('n'), new Letter('d'))));
+        'd'))));
-		words.add(new Word(Arrays.asList(new Letter('p'), new Letter('o'),
+    words.add(new Word(Arrays.asList(new Letter('p'), new Letter('o'), new Letter('u'), new Letter(
-				new Letter('u'), new Letter('r'), new Letter('s'))));
+        'r'), new Letter('s'))));
-		words.add(new Word(Arrays.asList(new Letter('f'), new Letter('r'),
+    words.add(new Word(Arrays.asList(new Letter('f'), new Letter('r'), new Letter('o'), new Letter(
-				new Letter('o'), new Letter('m'))));
+        'm'))));
-		words.add(new Word(Arrays.asList(new Letter('y'), new Letter('o'),
+    words.add(new Word(Arrays.asList(new Letter('y'), new Letter('o'), new Letter('u'), new Letter(
-				new Letter('u'), new Letter('r'))));
+        'r'))));
-		words.add(new Word(Arrays.asList(new Letter('m'), new Letter('o'),
+    words.add(new Word(Arrays.asList(new Letter('m'), new Letter('o'), new Letter('u'), new Letter(
-				new Letter('u'), new Letter('t'), new Letter('h'))));
+        't'), new Letter('h'))));
 
     return new Sentence(words);
 

composite/src/main/java/com/iluwatar/composite/Sentence.java

@@ -24,5 +24,4 @@ public class Sentence extends LetterComposite {
   protected void printThisAfter() {
     System.out.print(".");
   }
-
 }

composite/src/main/java/com/iluwatar/composite/Word.java

@@ -24,5 +24,4 @@ public class Word extends LetterComposite {
   protected void printThisAfter() {
     // nop
   }
-
 }

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

@@ -7,14 +7,16 @@ import org.apache.log4j.Logger;
 
 /**
  * 
- * Data Access Object (DAO) is an object that provides an abstract interface to some type of database or other 
+ * Data Access Object (DAO) is an object that provides an abstract interface to some type of
- * persistence mechanism. By mapping application calls to the persistence layer, DAO provide some specific data 
+ * database or other persistence mechanism. By mapping application calls to the persistence layer,
- * operations without exposing details of the database. This isolation supports the Single responsibility principle. 
+ * DAO provide some specific data operations without exposing details of the database. This
- * It separates what data accesses the application needs, in terms of domain-specific objects and data types 
+ * isolation supports the Single responsibility principle. It separates what data accesses the
- * (the public interface of the DAO), from how these needs can be satisfied with a specific DBMS.
+ * application needs, in terms of domain-specific objects and data types (the public interface of
+ * the DAO), from how these needs can be satisfied with a specific DBMS.
  * <p>
- * With the DAO pattern, we can use various method calls to retrieve/add/delete/update data without directly
+ * With the DAO pattern, we can use various method calls to retrieve/add/delete/update data without
- * interacting with the data. The below example demonstrates basic CRUD operations: select, add, update, and delete.
+ * directly interacting with the data. The below example demonstrates basic CRUD operations: select,
+ * add, update, and delete.
  * 
  */
 public class App {

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

@@ -2,21 +2,21 @@ package com.iluwatar.decorator;
 
 /**
  * 
- * The Decorator pattern is a more flexible alternative to subclassing. The Decorator
+ * The Decorator pattern is a more flexible alternative to subclassing. The Decorator class
- * class implements the same interface as the target and uses composition to
+ * implements the same interface as the target and uses composition to "decorate" calls to the
- * "decorate" calls to the target. Using the Decorator pattern it is possible to 
+ * target. Using the Decorator pattern it is possible to change the behavior of the class during
- * change the behavior of the class during runtime.
+ * runtime.
  * <p>
- * In this example we show how the simple {@link Troll} first attacks and then
+ * In this example we show how the simple {@link Troll} first attacks and then flees the battle.
- * flees the battle. Then we decorate the {@link Troll} with a {@link SmartTroll}
+ * Then we decorate the {@link Troll} with a {@link SmartTroll} and perform the attack again. You
- * and perform the attack again. You can see how the behavior changes after the
+ * can see how the behavior changes after the decoration.
- * decoration.
  * 
  */
 public class App {
 
   /**
    * Program entry point
+   * 
    * @param args command line args
    */
   public static void main(String[] args) {

decorator/src/main/java/com/iluwatar/decorator/SmartTroll.java

@@ -1,10 +1,9 @@
 package com.iluwatar.decorator;
 
 /**
- * SmartTroll is a decorator for {@link Hostile} objects.
+ * SmartTroll is a decorator for {@link Hostile} objects. The calls to the {@link Hostile} interface
- * The calls to the {@link Hostile} interface are intercepted
+ * are intercepted and decorated. Finally the calls are delegated to the decorated {@link Hostile}
- * and decorated. Finally the calls are delegated
+ * object.
- * to the decorated {@link Hostile} object.
  *
  */
 public class SmartTroll implements Hostile {
@@ -32,5 +31,4 @@ public class SmartTroll implements Hostile {
     System.out.println("The troll calls for help!");
     decorated.fleeBattle();
   }
-
 }

decorator/src/main/java/com/iluwatar/decorator/Troll.java

@@ -19,5 +19,4 @@ public class Troll implements Hostile {
   public void fleeBattle() {
     System.out.println("The troll shrieks in horror and runs away!");
   }
-
 }

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

@@ -2,9 +2,8 @@ package com.iluwatar.dependency.injection;
 
 /**
  * 
- * AdvancedWizard implements inversion of control.
+ * AdvancedWizard implements inversion of control. It depends on abstraction that can be injected
- * It depends on abstraction that can be injected through
+ * through its constructor.
- * its constructor.
  *
  */
 public class AdvancedWizard implements Wizard {

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

@@ -10,27 +10,28 @@ import com.google.inject.Injector;
  * - High-level modules should not depend on low-level modules. Both should depend on abstractions.
  * - Abstractions should not depend on details. Details should depend on abstractions.
  * <p>
- *  In this example we show you three different wizards. The first one ({@link SimpleWizard}) is a naive 
+ * In this example we show you three different wizards. The first one ({@link SimpleWizard}) is a
- *  implementation violating the inversion of control principle. It depends directly on a concrete
+ * naive implementation violating the inversion of control principle. It depends directly on a
- *  implementation which cannot be changed.
+ * concrete implementation which cannot be changed.
  * <p>
- *  The second wizard ({@link AdvancedWizard}) is more flexible. It does not depend on any concrete implementation 
+ * The second wizard ({@link AdvancedWizard}) is more flexible. It does not depend on any concrete
- *  but abstraction. It utilizes Dependency Injection pattern allowing its {@link Tobacco} dependency to be
+ * implementation but abstraction. It utilizes Dependency Injection pattern allowing its
- *  injected through its constructor. This way, handling the dependency is no longer the wizard's
+ * {@link Tobacco} dependency to be injected through its constructor. This way, handling the
- *  responsibility. It is resolved outside the wizard class.
+ * dependency is no longer the wizard's responsibility. It is resolved outside the wizard class.
  * <p>
- *  The third example takes the pattern a step further. It uses Guice framework for Dependency Injection.
+ * The third example takes the pattern a step further. It uses Guice framework for Dependency
- *  {@link TobaccoModule} binds a concrete implementation to abstraction. Injector is then used to create
+ * Injection. {@link TobaccoModule} binds a concrete implementation to abstraction. Injector is then
- *  {@link GuiceWizard} object with correct dependencies.
+ * used to create {@link GuiceWizard} object with correct dependencies.
  *
  */
 public class App {
 
   /**
    * Program entry point
+   * 
    * @param args command line args
    */
-    public static void main( String[] args ) {
+  public static void main(String[] args) {
     SimpleWizard simpleWizard = new SimpleWizard();
     simpleWizard.smoke();
 

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

@@ -4,9 +4,8 @@ import javax.inject.Inject;
 
 /**
  * 
- * GuiceWizard implements inversion of control.
+ * GuiceWizard implements inversion of control. Its dependencies are injected through its
- * Its dependencies are injected through its constructor
+ * constructor by Guice framework.
- * by Guice framework.
  *
  */
 public class GuiceWizard implements Wizard {

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

@@ -2,8 +2,8 @@ package com.iluwatar.dependency.injection;
 
 /**
  * 
- * Naive Wizard implementation violating the inversion of control principle.
+ * Naive Wizard implementation violating the inversion of control principle. It should depend on
- * It should depend on abstraction instead.
+ * abstraction instead.
  *
  */
 public class SimpleWizard implements Wizard {

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

@@ -8,6 +8,7 @@ package com.iluwatar.dependency.injection;
 public abstract class Tobacco {
 
   public void smoke(Wizard wizard) {
-		System.out.println(String.format("%s smoking %s", wizard.getClass().getSimpleName(), this.getClass().getSimpleName()));
+    System.out.println(String.format("%s smoking %s", wizard.getClass().getSimpleName(), this
+        .getClass().getSimpleName()));
   }
 }

double-checked-locking/src/main/java/com/iluwatar/doublechecked/locking/App.java

@@ -6,21 +6,21 @@ import java.util.concurrent.TimeUnit;
 
 /**
  * 
- * Double Checked Locking is a concurrency design pattern used to reduce the overhead 
+ * Double Checked Locking is a concurrency design pattern used to reduce the overhead of acquiring a
- * of acquiring a lock by first testing the locking criterion (the "lock hint") without 
+ * lock by first testing the locking criterion (the "lock hint") without actually acquiring the
- * actually acquiring the lock. Only if the locking criterion check indicates that 
+ * lock. Only if the locking criterion check indicates that locking is required does the actual
- * locking is required does the actual locking logic proceed.
+ * locking logic proceed.
  * <p>
- * In {@link Inventory} we store the items with a given size. However, we do not store
+ * In {@link Inventory} we store the items with a given size. However, we do not store more items
- * more items than the inventory size. To address concurrent access problems we
+ * than the inventory size. To address concurrent access problems we use double checked locking to
- * use double checked locking to add item to inventory. In this method, the
+ * add item to inventory. In this method, the thread which gets the lock first adds the item.
- * thread which gets the lock first adds the item.
  * 
  */
 public class App {
 
   /**
    * Program entry point
+   * 
    * @param args command line args
    */
   public static void main(String[] args) {
@@ -28,8 +28,7 @@ public class App {
     ExecutorService executorService = Executors.newFixedThreadPool(3);
     for (int i = 0; i < 3; i++) {
       executorService.execute(() -> {
-                while (inventory.addItem(new Item()))
+        while (inventory.addItem(new Item()));
-                    ;
       });
     }
 

double-checked-locking/src/main/java/com/iluwatar/doublechecked/locking/Inventory.java

@@ -28,8 +28,7 @@ public class Inventory {
       try {
         if (items.size() < inventorySize) {
           items.add(item);
-					System.out.println(Thread.currentThread()
+          System.out.println(Thread.currentThread() + ": items.size()=" + items.size()
-							+ ": items.size()=" + items.size()
               + ", inventorySize=" + inventorySize);
           return true;
         }
@@ -39,5 +38,4 @@ public class Inventory {
     }
     return false;
   }
-
 }

double-dispatch/src/main/java/com/iluwatar/doubledispatch/App.java

@@ -6,20 +6,20 @@ import java.util.List;
 /**
  * 
  * When a message with a parameter is sent to an object, the resultant behaviour is defined by the
- * implementation of that method in the receiver. Sometimes the behaviour must also be determined 
+ * implementation of that method in the receiver. Sometimes the behaviour must also be determined by
- * by the type of the parameter.
+ * the type of the parameter.
  * <p>
- * One way to implement this would be to create multiple instanceof-checks for the methods parameter.
+ * One way to implement this would be to create multiple instanceof-checks for the methods
- * However, this creates a maintenance issue. When new types are added we would also need to change
+ * parameter. However, this creates a maintenance issue. When new types are added we would also need
- * the method's implementation and add a new instanceof-check. This violates the single responsibility
+ * to change the method's implementation and add a new instanceof-check. This violates the single
- * principle - a class should have only one reason to change.
+ * responsibility principle - a class should have only one reason to change.
  * <p>
  * Instead of the instanceof-checks a better way is to make another virtual call on the parameter
  * object. This way new functionality can be easily added without the need to modify existing
  * implementation (open-closed principle).
  * <p>
- * In this example we have hierarchy of objects ({@link GameObject}) that can collide to each other. Each
+ * In this example we have hierarchy of objects ({@link GameObject}) that can collide to each other.
- * object has its own coordinates which are checked against the other objects' coordinates. If
+ * Each object has its own coordinates which are checked against the other objects' coordinates. If
  * there is an overlap, then the objects collide utilizing the Double Dispatch pattern.
  *
  */
@@ -27,9 +27,10 @@ public class App {
 
   /**
    * Program entry point
+   * 
    * @param args command line args
    */
-    public static void main( String[] args ) {
+  public static void main(String[] args) {
     // initialize game objects and print their status
     List<GameObject> objects = new ArrayList<>();
     objects.add(new FlamingAsteroid(0, 0, 5, 5));
@@ -40,7 +41,10 @@ public class App {
     System.out.println("");
 
     // collision check
-    	objects.stream().forEach(o1 -> objects.stream().forEach(o2 -> { if (o1 != o2 && o1.intersectsWith(o2)) o1.collision(o2); } ));
+    objects.stream().forEach(o1 -> objects.stream().forEach(o2 -> {
+      if (o1 != o2 && o1.intersectsWith(o2))
+        o1.collision(o2);
+    }));
     System.out.println("");
 
     // output eventual object statuses

double-dispatch/src/main/java/com/iluwatar/doubledispatch/GameObject.java

@@ -2,8 +2,7 @@ package com.iluwatar.doubledispatch;
 
 /**
  * 
- * Game objects have coordinates and some
+ * Game objects have coordinates and some other status information.
- * other status information.
  *
  */
 public abstract class GameObject extends Rectangle {

double-dispatch/src/main/java/com/iluwatar/doubledispatch/Meteoroid.java

@@ -18,21 +18,25 @@ public class Meteoroid extends GameObject {
 
   @Override
   public void collisionResolve(FlamingAsteroid asteroid) {
-		System.out.println(String.format("%s hits %s.", asteroid.getClass().getSimpleName(), this.getClass().getSimpleName()));
+    System.out.println(String.format("%s hits %s.", asteroid.getClass().getSimpleName(), this
+        .getClass().getSimpleName()));
   }
 
   @Override
   public void collisionResolve(Meteoroid meteoroid) {
-		System.out.println(String.format("%s hits %s.", meteoroid.getClass().getSimpleName(), this.getClass().getSimpleName()));
+    System.out.println(String.format("%s hits %s.", meteoroid.getClass().getSimpleName(), this
+        .getClass().getSimpleName()));
   }
 
   @Override
   public void collisionResolve(SpaceStationMir mir) {
-		System.out.println(String.format("%s hits %s.", mir.getClass().getSimpleName(), this.getClass().getSimpleName()));
+    System.out.println(String.format("%s hits %s.", mir.getClass().getSimpleName(), this.getClass()
+        .getSimpleName()));
   }
 
   @Override
   public void collisionResolve(SpaceStationIss iss) {
-		System.out.println(String.format("%s hits %s.", iss.getClass().getSimpleName(), this.getClass().getSimpleName()));
+    System.out.println(String.format("%s hits %s.", iss.getClass().getSimpleName(), this.getClass()
+        .getSimpleName()));
   }
 }

double-dispatch/src/main/java/com/iluwatar/doubledispatch/Rectangle.java

@@ -2,8 +2,7 @@ package com.iluwatar.doubledispatch;
 
 /**
  * 
- * Rectangle has coordinates and can be checked for overlap against
+ * Rectangle has coordinates and can be checked for overlap against other Rectangles.
- * other Rectangles.
  *
  */
 public class Rectangle {
@@ -23,18 +22,22 @@ public class Rectangle {
   public int getLeft() {
     return left;
   }
+
   public int getTop() {
     return top;
   }
+
   public int getRight() {
     return right;
   }
+
   public int getBottom() {
     return bottom;
   }
 
   boolean intersectsWith(Rectangle r) {
-		return !(r.getLeft() > getRight() || r.getRight() < getLeft() || r.getTop() > getBottom() || r.getBottom() < getTop());
+    return !(r.getLeft() > getRight() || r.getRight() < getLeft() || r.getTop() > getBottom() || r
+        .getBottom() < getTop());
   }
 
   @Override

double-dispatch/src/main/java/com/iluwatar/doubledispatch/SpaceStationMir.java

@@ -18,34 +18,31 @@ public class SpaceStationMir extends GameObject {
 
   @Override
   public void collisionResolve(FlamingAsteroid asteroid) {
-		System.out.println(String.format("%s hits %s. %s is damaged! %s is set on fire!", 
+    System.out.println(String.format("%s hits %s. %s is damaged! %s is set on fire!", asteroid
-				asteroid.getClass().getSimpleName(), this.getClass().getSimpleName(), 
+        .getClass().getSimpleName(), this.getClass().getSimpleName(), this.getClass()
-				this.getClass().getSimpleName(), this.getClass().getSimpleName()));
+        .getSimpleName(), this.getClass().getSimpleName()));
     setDamaged(true);
     setOnFire(true);
   }
 
   @Override
   public void collisionResolve(Meteoroid meteoroid) {
-		System.out.println(String.format("%s hits %s. %s is damaged!", 
+    System.out.println(String.format("%s hits %s. %s is damaged!", meteoroid.getClass()
-				meteoroid.getClass().getSimpleName(), this.getClass().getSimpleName(), 
+        .getSimpleName(), this.getClass().getSimpleName(), this.getClass().getSimpleName()));
-				this.getClass().getSimpleName()));
     setDamaged(true);
   }
 
   @Override
   public void collisionResolve(SpaceStationMir mir) {
-		System.out.println(String.format("%s hits %s. %s is damaged!", 
+    System.out.println(String.format("%s hits %s. %s is damaged!", mir.getClass().getSimpleName(),
-				mir.getClass().getSimpleName(), this.getClass().getSimpleName(), 
+        this.getClass().getSimpleName(), this.getClass().getSimpleName()));
-				this.getClass().getSimpleName()));
     setDamaged(true);
   }
 
   @Override
   public void collisionResolve(SpaceStationIss iss) {
-		System.out.println(String.format("%s hits %s. %s is damaged!", 
+    System.out.println(String.format("%s hits %s. %s is damaged!", iss.getClass().getSimpleName(),
-				iss.getClass().getSimpleName(), this.getClass().getSimpleName(), 
+        this.getClass().getSimpleName(), this.getClass().getSimpleName()));
-				this.getClass().getSimpleName()));
     setDamaged(true);
   }
 }

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

@@ -14,9 +14,9 @@ public class RectangleTest {
 
   @Test
   public void test() {
-		Assert.assertTrue(new Rectangle(0,0,1,1).intersectsWith(new Rectangle(0,0,1,1)));
+    Assert.assertTrue(new Rectangle(0, 0, 1, 1).intersectsWith(new Rectangle(0, 0, 1, 1)));
-		Assert.assertTrue(new Rectangle(0,0,1,1).intersectsWith(new Rectangle(-1,-5,7,8)));
+    Assert.assertTrue(new Rectangle(0, 0, 1, 1).intersectsWith(new Rectangle(-1, -5, 7, 8)));
-		Assert.assertFalse(new Rectangle(0,0,1,1).intersectsWith(new Rectangle(2,2,3,3)));
+    Assert.assertFalse(new Rectangle(0, 0, 1, 1).intersectsWith(new Rectangle(2, 2, 3, 3)));
-		Assert.assertFalse(new Rectangle(0,0,1,1).intersectsWith(new Rectangle(-2,-2,-1,-1)));
+    Assert.assertFalse(new Rectangle(0, 0, 1, 1).intersectsWith(new Rectangle(-2, -2, -1, -1)));
   }
 }

event-aggregator/src/main/java/com/iluwatar/event/aggregator/App.java

@@ -5,22 +5,23 @@ import java.util.List;
 
 /**
  * 
- * A system with lots of objects can lead to complexities when a client wants to subscribe 
+ * A system with lots of objects can lead to complexities when a client wants to subscribe to
- * to events. The client has to find and register for each object individually, if each 
+ * events. The client has to find and register for each object individually, if each object has
- * object has multiple events then each event requires a separate subscription.
+ * multiple events then each event requires a separate subscription.
  * <p>
- * An Event Aggregator acts as a single source of events for many objects. It registers 
+ * An Event Aggregator acts as a single source of events for many objects. It registers for all the
- * for all the events of the many objects allowing clients to register with just the aggregator.
+ * events of the many objects allowing clients to register with just the aggregator.
  * <p>
  * In the example {@link LordBaelish}, {@link LordVarys} and {@link Scout} deliver events to
- * {@link KingsHand}. {@link KingsHand}, the event aggregator, then delivers the events
+ * {@link KingsHand}. {@link KingsHand}, the event aggregator, then delivers the events to
- * to {@link KingJoffrey}.
+ * {@link KingJoffrey}.
  *
  */
 public class App {
 
   /**
    * Program entry point
+   * 
    * @param args command line args
    */
   public static void main(String[] args) {
@@ -34,8 +35,8 @@ public class App {
     emitters.add(new LordVarys(kingsHand));
     emitters.add(new Scout(kingsHand));
 
-		for (Weekday day: Weekday.values()) {
+    for (Weekday day : Weekday.values()) {
-			for (EventEmitter emitter: emitters) {
+      for (EventEmitter emitter : emitters) {
         emitter.timePasses(day);
       }
     }

event-aggregator/src/main/java/com/iluwatar/event/aggregator/Event.java

@@ -7,7 +7,8 @@ package com.iluwatar.event.aggregator;
  */
 public enum Event {
 
-	STARK_SIGHTED("Stark sighted"), WARSHIPS_APPROACHING("Warships approaching"), TRAITOR_DETECTED("Traitor detected");
+  STARK_SIGHTED("Stark sighted"), WARSHIPS_APPROACHING("Warships approaching"), TRAITOR_DETECTED(
+      "Traitor detected");
 
   private String description;
 

event-aggregator/src/main/java/com/iluwatar/event/aggregator/EventEmitter.java

@@ -26,7 +26,7 @@ public abstract class EventEmitter {
   }
 
   protected void notifyObservers(Event e) {
-		for (EventObserver obs: observers) {
+    for (EventObserver obs : observers) {
       obs.onEvent(e);
     }
   }

event-aggregator/src/main/java/com/iluwatar/event/aggregator/KingsHand.java

@@ -2,8 +2,7 @@ package com.iluwatar.event.aggregator;
 
 /**
  * 
- * KingsHand observes events from multiple sources and delivers them
+ * KingsHand observes events from multiple sources and delivers them to listeners.
- * to listeners.
  *
  */
 public class KingsHand extends EventEmitter implements EventObserver {

event-aggregator/src/main/java/com/iluwatar/event/aggregator/Weekday.java

@@ -7,7 +7,8 @@ package com.iluwatar.event.aggregator;
  */
 public enum Weekday {
 
-	MONDAY("Monday"), TUESDAY("Tuesday"), WEDNESDAY("Wednesday"), THURSDAY("Thursday"), FRIDAY("Friday"), SATURDAY("Saturday"), SUNDAY("Sunday");
+  MONDAY("Monday"), TUESDAY("Tuesday"), WEDNESDAY("Wednesday"), THURSDAY("Thursday"), FRIDAY(
+      "Friday"), SATURDAY("Saturday"), SUNDAY("Sunday");
 
   private String description;
 

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

@@ -1,4 +1,5 @@
 package com.iluwatar.event.aggregator;
+
 import org.junit.Test;
 
 import com.iluwatar.event.aggregator.App;

execute-around/src/main/java/com/iluwatar/execute/around/App.java

@@ -4,23 +4,24 @@ import java.io.FileWriter;
 import java.io.IOException;
 
 /**
- * The Execute Around idiom specifies some code to be executed before and after
+ * The Execute Around idiom specifies some code to be executed before and after a method. Typically
- * a method. Typically the idiom is used when the API has methods to be executed in
+ * the idiom is used when the API has methods to be executed in pairs, such as resource
- * pairs, such as resource allocation/deallocation or lock acquisition/release.
+ * allocation/deallocation or lock acquisition/release.
  * <p>
- * In this example, we have {@link SimpleFileWriter} class that opens and closes the file
+ * In this example, we have {@link SimpleFileWriter} class that opens and closes the file for the
- * for the user. The user specifies only what to do with the file by providing the
+ * user. The user specifies only what to do with the file by providing the {@link FileWriterAction}
- * {@link FileWriterAction} implementation.
+ * implementation.
  *
  */
 public class App {
 
   /**
    * Program entry point
+   * 
    * @param args command line args
    * @throws IOException
    */
-    public static void main( String[] args ) throws IOException {
+  public static void main(String[] args) throws IOException {
 
     new SimpleFileWriter("testfile.txt", new FileWriterAction() {
 

execute-around/src/main/java/com/iluwatar/execute/around/SimpleFileWriter.java

@@ -5,9 +5,8 @@ import java.io.IOException;
 
 /**
  * 
- * SimpleFileWriter handles opening and closing file for the user. The user
+ * SimpleFileWriter handles opening and closing file for the user. The user only has to specify what
- * only has to specify what to do with the file resource through {@link FileWriterAction}
+ * to do with the file resource through {@link FileWriterAction} parameter.
- * parameter.
  *
  */
 public class SimpleFileWriter {

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

@@ -2,21 +2,22 @@ package com.iluwatar.facade;
 
 /**
  * 
- * The Facade design pattern is often used when a system is very complex or difficult 
+ * The Facade design pattern is often used when a system is very complex or difficult to understand
- * to understand because the system has a large number of interdependent classes or 
+ * because the system has a large number of interdependent classes or its source code is
- * its source code is unavailable. This pattern hides the complexities of the larger 
+ * unavailable. This pattern hides the complexities of the larger system and provides a simpler
- * system and provides a simpler interface to the client. It typically involves a single 
+ * interface to the client. It typically involves a single wrapper class which contains a set of
- * wrapper class which contains a set of members required by client. These members access 
+ * members required by client. These members access the system on behalf of the facade client and
- * the system on behalf of the facade client and hide the implementation details.
+ * hide the implementation details.
  * <p>
- * In this example the Facade is ({@link DwarvenGoldmineFacade}) and it provides a simpler 
+ * In this example the Facade is ({@link DwarvenGoldmineFacade}) and it provides a simpler interface
- * interface to the goldmine subsystem.
+ * to the goldmine subsystem.
  * 
  */
 public class App {
 
   /**
    * Program entry point
+   * 
    * @param args command line args
    */
   public static void main(String[] args) {

facade/src/main/java/com/iluwatar/facade/DwarvenCartOperator.java

@@ -16,5 +16,4 @@ public class DwarvenCartOperator extends DwarvenMineWorker {
   public String name() {
     return "Dwarf cart operator";
   }
-
 }

facade/src/main/java/com/iluwatar/facade/DwarvenGoldDigger.java

@@ -16,5 +16,4 @@ public class DwarvenGoldDigger extends DwarvenMineWorker {
   public String name() {
     return "Dwarf gold digger";
   }
-
 }

facade/src/main/java/com/iluwatar/facade/DwarvenGoldmineFacade.java

@@ -6,12 +6,10 @@ import java.util.List;
 
 /**
  * 
- * DwarvenGoldmineFacade provides a single interface
+ * DwarvenGoldmineFacade provides a single interface through which users can operate the subsystems.
- * through which users can operate the subsystems.
  * 
- * This makes the goldmine easier to operate and
+ * This makes the goldmine easier to operate and cuts the dependencies from the goldmine user to the
- * cuts the dependencies from the goldmine user to
+ * subsystems.
- * the subsystems.
  *
  */
 public class DwarvenGoldmineFacade {
@@ -37,7 +35,8 @@ public class DwarvenGoldmineFacade {
     makeActions(workers, DwarvenMineWorker.Action.GO_HOME, DwarvenMineWorker.Action.GO_TO_SLEEP);
   }
 
-    private void makeActions(Collection<DwarvenMineWorker> workers, DwarvenMineWorker.Action... actions) {
+  private void makeActions(Collection<DwarvenMineWorker> workers,
+      DwarvenMineWorker.Action... actions) {
     for (DwarvenMineWorker worker : workers) {
       worker.action(actions);
     }

facade/src/main/java/com/iluwatar/facade/DwarvenTunnelDigger.java

@@ -16,5 +16,4 @@ public class DwarvenTunnelDigger extends DwarvenMineWorker {
   public String name() {
     return "Dwarven tunnel digger";
   }
-
 }

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

@@ -2,23 +2,23 @@ package com.iluwatar.factory.method;
 
 /**
  * 
- * The Factory Method is a creational design pattern which uses factory methods to deal 
+ * The Factory Method is a creational design pattern which uses factory methods to deal with the
- * with the problem of creating objects without specifying the exact class of object 
+ * problem of creating objects without specifying the exact class of object that will be created.
- * that will be created. This is done by creating objects via calling a factory 
+ * This is done by creating objects via calling a factory method either specified in an interface
- * method either specified in an interface and implemented by child classes, or implemented 
+ * and implemented by child classes, or implemented in a base class and optionally overridden by
- * in a base class and optionally overridden by derived classes—rather than by calling a 
+ * derived classes—rather than by calling a constructor.
- * constructor.
  * <p>
  * In this Factory Method example we have an interface ({@link Blacksmith}) with a method for
- * creating objects ({@link Blacksmith#manufactureWeapon}). The concrete subclasses 
+ * creating objects ({@link Blacksmith#manufactureWeapon}). The concrete subclasses (
- * ({@link OrcBlacksmith}, {@link ElfBlacksmith}) then override the method to produce 
+ * {@link OrcBlacksmith}, {@link ElfBlacksmith}) then override the method to produce objects of
- * objects of their liking.
+ * their liking.
  * 
  */
 public class App {
 
   /**
    * Program entry point
+   * 
    * @param args command line args
    */
   public static void main(String[] args) {

factory-method/src/main/java/com/iluwatar/factory/method/ElfWeapon.java

@@ -17,5 +17,4 @@ public class ElfWeapon implements Weapon {
   public String toString() {
     return "Elven " + weaponType;
   }
-
 }

factory-method/src/main/java/com/iluwatar/factory/method/OrcBlacksmith.java

@@ -10,5 +10,4 @@ public class OrcBlacksmith implements Blacksmith {
   public Weapon manufactureWeapon(WeaponType weaponType) {
     return new OrcWeapon(weaponType);
   }
-
 }

factory-method/src/main/java/com/iluwatar/factory/method/OrcWeapon.java

@@ -17,5 +17,4 @@ public class OrcWeapon implements Weapon {
   public String toString() {
     return "Orcish " + weaponType;
   }
-
 }

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

@@ -11,13 +11,15 @@ import java.util.function.Predicate;
 import static java.lang.String.valueOf;
 
 /**
- * The Fluent Interface pattern is useful when you want to provide an easy readable, flowing API. Those
+ * The Fluent Interface pattern is useful when you want to provide an easy readable, flowing API.
- * interfaces tend to mimic domain specific languages, so they can nearly be read as human languages.
+ * Those interfaces tend to mimic domain specific languages, so they can nearly be read as human
+ * languages.
  * <p>
  * In this example two implementations of a {@link FluentIterable} interface are given. The
- * {@link SimpleFluentIterable} evaluates eagerly and would be too costly for real world applications. 
+ * {@link SimpleFluentIterable} evaluates eagerly and would be too costly for real world
- * The {@link LazyFluentIterable} is evaluated on termination. Their usage is demonstrated with a 
+ * applications. The {@link LazyFluentIterable} is evaluated on termination. Their usage is
- * simple number list that is filtered, transformed and collected. The result is printed afterwards.
+ * demonstrated with a simple number list that is filtered, transformed and collected. The result is
+ * printed afterwards.
  * 
  */
 public class App {
@@ -25,10 +27,8 @@ public class App {
   public static void main(String[] args) {
 
     List<Integer> integerList = new ArrayList<>();
-    integerList.addAll(Arrays.asList(
+    integerList.addAll(Arrays.asList(1, -61, 14, -22, 18, -87, 6, 64, -82, 26, -98, 97, 45, 23, 2,
-    		1, -61, 14, -22, 18, -87, 6, 64, -82, 26, -98, 97,
+        -68, 45));
-    		45, 23, 2, -68, 45
-    ));
 
     prettyPrint("The initial list contains: ", integerList);
 

flux/src/main/java/com/iluwatar/flux/action/Content.java

@@ -7,7 +7,8 @@ package com.iluwatar.flux.action;
  */
 public enum Content {
 
-	PRODUCTS("Products - This page lists the company's products."), COMPANY("Company - This page displays information about the company.");
+  PRODUCTS("Products - This page lists the company's products."), COMPANY(
+      "Company - This page displays information about the company.");
 
   private String title;
 

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

@@ -11,13 +11,14 @@ import com.iluwatar.flux.view.MenuView;
  * 
  * Flux is the application architecture that Facebook uses for building client-side web
  * applications. Flux eschews MVC in favor of a unidirectional data flow. When a user interacts with
- * a React view, the view propagates an action through a central dispatcher, to the various stores that 
+ * a React view, the view propagates an action through a central dispatcher, to the various stores
- * hold the application's data and business logic, which updates all of the views that are affected.  
+ * that hold the application's data and business logic, which updates all of the views that are
+ * affected.
  * <p>
- * This example has two views: menu and content. They represent typical main menu and content area of
+ * This example has two views: menu and content. They represent typical main menu and content area
- * a web page. When menu item is clicked it triggers events through the dispatcher. The events are
+ * of a web page. When menu item is clicked it triggers events through the dispatcher. The events
- * received and handled by the stores updating their data as needed. The stores then notify the views
+ * are received and handled by the stores updating their data as needed. The stores then notify the
- * that they should rerender themselves.
+ * views that they should rerender themselves.
  * <p>
  * http://facebook.github.io/flux/docs/overview.html
  *
@@ -26,9 +27,10 @@ public class App {
 
   /**
    * Program entry point
+   * 
    * @param args command line args
    */
-    public static void main( String[] args ) {
+  public static void main(String[] args) {
 
     // initialize and wire the system
     MenuStore menuStore = new MenuStore();

flux/src/main/java/com/iluwatar/flux/dispatcher/Dispatcher.java

@@ -21,8 +21,7 @@ public class Dispatcher {
 
   private List<Store> stores = new LinkedList<>();
 
-	private Dispatcher() {	
+  private Dispatcher() {}
-	}
 
   public static Dispatcher getInstance() {
     return instance;

flux/src/main/java/com/iluwatar/flux/view/MenuView.java

@@ -23,7 +23,7 @@ public class MenuView implements View {
 
   @Override
   public void render() {
-		for (MenuItem item: MenuItem.values()) {
+    for (MenuItem item : MenuItem.values()) {
       if (selected.equals(item)) {
         System.out.println(String.format("* %s", item.toString()));
       } else {

flyweight/src/main/java/com/iluwatar/flyweight/AlchemistShop.java

@@ -5,8 +5,7 @@ import java.util.List;
 
 /**
  * 
- * AlchemistShop holds potions on its shelves.
+ * AlchemistShop holds potions on its shelves. It uses PotionFactory to provide the potions.
- * It uses PotionFactory to provide the potions.
  * 
  */
 public class AlchemistShop {

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

@@ -2,22 +2,23 @@ package com.iluwatar.flyweight;
 
 /**
  * 
- * Flyweight pattern is useful when the program needs a huge amount of objects.
+ * Flyweight pattern is useful when the program needs a huge amount of objects. It provides means to
- * It provides means to decrease resource usage by sharing object instances.
+ * decrease resource usage by sharing object instances.
  * <p>
- * In this example {@link AlchemistShop} has great amount of potions on its shelves.
+ * In this example {@link AlchemistShop} has great amount of potions on its shelves. To fill the
- * To fill the shelves {@link AlchemistShop} uses {@link PotionFactory} (which represents
+ * shelves {@link AlchemistShop} uses {@link PotionFactory} (which represents the Flyweight in this
- * the Flyweight in this example). Internally {@link PotionFactory} holds a map
+ * example). Internally {@link PotionFactory} holds a map of the potions and lazily creates new ones
- * of the potions and lazily creates new ones when requested.
+ * when requested.
  * <p>
- * To enable safe sharing, between clients and threads, Flyweight objects must 
+ * To enable safe sharing, between clients and threads, Flyweight objects must be immutable.
- * be immutable. Flyweight objects are by definition value objects.
+ * Flyweight objects are by definition value objects.
  * 
  */
 public class App {
 
   /**
    * Program entry point
+   * 
    * @param args command line args
    */
   public static void main(String[] args) {

flyweight/src/main/java/com/iluwatar/flyweight/HealingPotion.java

@@ -9,8 +9,6 @@ public class HealingPotion implements Potion {
 
   @Override
   public void drink() {
-		System.out.println("You feel healed. (Potion="
+    System.out.println("You feel healed. (Potion=" + System.identityHashCode(this) + ")");
-				+ System.identityHashCode(this) + ")");
   }
-
 }

flyweight/src/main/java/com/iluwatar/flyweight/HolyWaterPotion.java

@@ -9,8 +9,6 @@ public class HolyWaterPotion implements Potion {
 
   @Override
   public void drink() {
-		System.out.println("You feel blessed. (Potion="
+    System.out.println("You feel blessed. (Potion=" + System.identityHashCode(this) + ")");
-				+ System.identityHashCode(this) + ")");
   }
-
 }

flyweight/src/main/java/com/iluwatar/flyweight/InvisibilityPotion.java

@@ -9,8 +9,6 @@ public class InvisibilityPotion implements Potion {
 
   @Override
   public void drink() {
-		System.out.println("You become invisible. (Potion="
+    System.out.println("You become invisible. (Potion=" + System.identityHashCode(this) + ")");
-				+ System.identityHashCode(this) + ")");
   }
-
 }

flyweight/src/main/java/com/iluwatar/flyweight/PoisonPotion.java

@@ -9,8 +9,6 @@ public class PoisonPotion implements Potion {
 
   @Override
   public void drink() {
-		System.out.println("Urgh! This is poisonous. (Potion="
+    System.out.println("Urgh! This is poisonous. (Potion=" + System.identityHashCode(this) + ")");
-				+ System.identityHashCode(this) + ")");
   }
-
 }

flyweight/src/main/java/com/iluwatar/flyweight/PotionFactory.java

@@ -5,10 +5,9 @@ import java.util.Map;
 
 /**
  * 
- * PotionFactory is the Flyweight in this example.
+ * PotionFactory is the Flyweight in this example. It minimizes memory use by sharing object
- * It minimizes memory use by sharing object instances.
+ * instances. It holds a map of potion instances and new potions are created only when none of the
- * It holds a map of potion instances and new potions
+ * type already exists.
- * are created only when none of the type already exists.
  * 
  */
 public class PotionFactory {

flyweight/src/main/java/com/iluwatar/flyweight/StrengthPotion.java

@@ -9,7 +9,6 @@ public class StrengthPotion implements Potion {
 
   @Override
   public void drink() {
-		System.out.println("You feel strong. (Potion="
+    System.out.println("You feel strong. (Potion=" + System.identityHashCode(this) + ")");
-				+ System.identityHashCode(this) + ")");
   }
 }

half-sync-half-async/src/main/java/com/iluwatar/halfsynchalfasync/App.java

@@ -8,63 +8,62 @@ import java.util.concurrent.LinkedBlockingQueue;
  * {@link AsyncTask} and {@link AsynchronousService}.
  * 
  * <p>
- * <i>PROBLEM</i>
+ * <i>PROBLEM</i> <br/>
- * <br/>
+ * A concurrent system have a mixture of short duration, mid duration and long duration tasks. Mid
- * A concurrent system have a mixture of short duration, mid duration and long duration tasks.
+ * or long duration tasks should be performed asynchronously to meet quality of service
- * Mid or long duration tasks should be performed asynchronously to meet quality of service
  * requirements.
  * 
- * <p><i>INTENT</i>
+ * <p>
- * <br/>
+ * <i>INTENT</i> <br/>
- * The intent of this pattern is to separate the the synchronous and asynchronous processing
+ * The intent of this pattern is to separate the the synchronous and asynchronous processing in the
- * in the concurrent application by introducing two intercommunicating layers - one for sync
+ * concurrent application by introducing two intercommunicating layers - one for sync and one for
- * and one for async. This simplifies the programming without unduly affecting the performance.
+ * async. This simplifies the programming without unduly affecting the performance.
  * 
  * <p>
- * <i>APPLICABILITY</i>
+ * <i>APPLICABILITY</i> <br/>
- * <br/>
  * <ul>
  * <li>UNIX network subsystems - In operating systems network operations are carried out
  * asynchronously with help of hardware level interrupts.</li>
- * <li>CORBA - At the asynchronous layer one thread is associated with each socket that is
+ * <li>CORBA - At the asynchronous layer one thread is associated with each socket that is connected
- * connected to the client. Thread blocks waiting for CORBA requests from the client. On receiving
+ * to the client. Thread blocks waiting for CORBA requests from the client. On receiving request it
- * request it is inserted in the queuing layer which is then picked up by synchronous layer which
+ * is inserted in the queuing layer which is then picked up by synchronous layer which processes the
- * processes the request and sends response back to the client.</li>
+ * request and sends response back to the client.</li>
- * <li>Android AsyncTask framework - Framework provides a way to execute long running blocking calls,
+ * <li>Android AsyncTask framework - Framework provides a way to execute long running blocking
- * such as downloading a file, in background threads so that the UI thread remains free to respond
+ * calls, such as downloading a file, in background threads so that the UI thread remains free to
- * to user inputs.</i>
+ * respond to user inputs.</i>
  * </ul>
  * 
  * <p>
- * <i>IMPLEMENTATION</i>
+ * <i>IMPLEMENTATION</i> <br/>
- * <br/>
+ * The main method creates an asynchronous service which does not block the main thread while the
- * The main method creates an asynchronous service which does not block the main thread while
+ * task is being performed. The main thread continues its work which is similar to Async Method
- * the task is being performed. The main thread continues its work which is similar to Async Method
+ * Invocation pattern. The difference between them is that there is a queuing layer between
- * Invocation pattern. The difference between them is that there is a queuing layer between Asynchronous
+ * Asynchronous layer and synchronous layer, which allows for different communication patterns
- * layer and synchronous layer, which allows for different communication patterns between both layers.
+ * between both layers. Such as Priority Queue can be used as queuing layer to prioritize the way
- * Such as Priority Queue can be used as queuing layer to prioritize the way tasks are executed.
+ * tasks are executed. Our implementation is just one simple way of implementing this pattern, there
- * Our implementation is just one simple way of implementing this pattern, there are many variants possible
+ * are many variants possible as described in its applications.
- * as described in its applications.
  * 
  */
 public class App {
 
   /**
    * Program entry point
+   * 
    * @param args command line args
    */
   public static void main(String[] args) {
     AsynchronousService service = new AsynchronousService(new LinkedBlockingQueue<>());
     /*
-		 *  A new task to calculate sum is received but as this is main thread, it should not block.
+     * A new task to calculate sum is received but as this is main thread, it should not block. So
-		 *  So it passes it to the asynchronous task layer to compute and proceeds with handling other
+     * it passes it to the asynchronous task layer to compute and proceeds with handling other
-		 *  incoming requests. This is particularly useful when main thread is waiting on Socket to receive
+     * incoming requests. This is particularly useful when main thread is waiting on Socket to
-		 *  new incoming requests and does not wait for particular request to be completed before responding
+     * receive new incoming requests and does not wait for particular request to be completed before
-		 *  to new request.
+     * responding to new request.
      */
     service.execute(new ArithmeticSumTask(1000));
 
-		/* New task received, lets pass that to async layer for computation. So both requests will be
+    /*
+     * New task received, lets pass that to async layer for computation. So both requests will be
      * executed in parallel.
      */
     service.execute(new ArithmeticSumTask(500));
@@ -85,8 +84,8 @@ public class App {
     }
 
     /*
-		 * This is the long running task that is performed in background. In our example 
+     * This is the long running task that is performed in background. In our example the long
-		 * the long running task is calculating arithmetic sum with artificial delay.
+     * running task is calculating arithmetic sum with artificial delay.
      */
     @Override
     public Long call() throws Exception {
@@ -94,11 +93,10 @@ public class App {
     }
 
     /*
-		 * This will be called in context of the main thread where some validations can be
+     * This will be called in context of the main thread where some validations can be done
-		 * done regarding the inputs. Such as it must be greater than 0. It's a small
+     * regarding the inputs. Such as it must be greater than 0. It's a small computation which can
-		 * computation which can be performed in main thread. If we did validated the input
+     * be performed in main thread. If we did validated the input in background thread then we pay
-		 * in background thread then we pay the cost of context switching
+     * the cost of context switching which is much more than validating it in main thread.
-		 * which is much more than validating it in main thread. 
      */
     @Override
     public void onPreCall() {

half-sync-half-async/src/main/java/com/iluwatar/halfsynchalfasync/AsyncTask.java

@@ -3,41 +3,41 @@ package com.iluwatar.halfsynchalfasync;
 import java.util.concurrent.Callable;
 
 /**
- * Represents some computation that is performed asynchronously and its result. 
+ * Represents some computation that is performed asynchronously and its result. The computation is
- * The computation is typically done is background threads and the result is posted 
+ * typically done is background threads and the result is posted back in form of callback. The
- * back in form of callback. The callback does not implement {@code isComplete}, {@code cancel} 
+ * callback does not implement {@code isComplete}, {@code cancel} as it is out of scope of this
- * as it is out of scope of this pattern.
+ * pattern.
  * 
  * @param <O> type of result
  */
 public interface AsyncTask<O> extends Callable<O> {
   /**
-	 * Is called in context of caller thread before call to {@link #call()}. Large
+   * Is called in context of caller thread before call to {@link #call()}. Large tasks should not be
-	 * tasks should not be performed in this method as it will block the caller thread.
+   * performed in this method as it will block the caller thread. Small tasks such as validations
-	 * Small tasks such as validations can be performed here so that the performance penalty
+   * can be performed here so that the performance penalty of context switching is not incurred in
-	 * of context switching is not incurred in case of invalid requests.
+   * case of invalid requests.
    */
   void onPreCall();
 
   /**
    * A callback called after the result is successfully computed by {@link #call()}. In our
-	 * implementation this method is called in context of background thread but in some variants,
+   * implementation this method is called in context of background thread but in some variants, such
-	 * such as Android where only UI thread can change the state of UI widgets, this method is called
+   * as Android where only UI thread can change the state of UI widgets, this method is called in
-	 * in context of UI thread.
+   * context of UI thread.
    */
   void onPostCall(O result);
 
   /**
-	 * A callback called if computing the task resulted in some exception. This method
+   * A callback called if computing the task resulted in some exception. This method is called when
-	 * is called when either of {@link #call()} or {@link #onPreCall()} throw any exception.
+   * either of {@link #call()} or {@link #onPreCall()} throw any exception.
    * 
    * @param throwable error cause
    */
   void onError(Throwable throwable);
 
   /**
-	 * This is where the computation of task should reside. This method is called in context
+   * This is where the computation of task should reside. This method is called in context of
-	 * of background thread.
+   * background thread.
    */
   @Override
   O call() throws Exception;

half-sync-half-async/src/main/java/com/iluwatar/halfsynchalfasync/AsynchronousService.java

@@ -9,25 +9,25 @@ import java.util.concurrent.TimeUnit;
 
 /**
  * This is the asynchronous layer which does not block when a new request arrives. It just passes
- * the request to the synchronous layer which consists of a queue i.e. a {@link BlockingQueue} and
+ * the request to the synchronous layer which consists of a queue i.e. a {@link BlockingQueue} and a
- * a pool of threads i.e. {@link ThreadPoolExecutor}. Out of this pool of worker threads one of the 
+ * pool of threads i.e. {@link ThreadPoolExecutor}. Out of this pool of worker threads one of the
- * thread picks up the task and executes it synchronously in background and the result is posted back
+ * thread picks up the task and executes it synchronously in background and the result is posted
- * to the caller via callback.
+ * back to the caller via callback.
  */
 public class AsynchronousService {
 
   /*
-	 * This represents the queuing layer as well as synchronous layer of the pattern. The thread
+   * This represents the queuing layer as well as synchronous layer of the pattern. The thread pool
-	 * pool contains worker threads which execute the tasks in blocking/synchronous manner. Long
+   * contains worker threads which execute the tasks in blocking/synchronous manner. Long running
-	 * running tasks should be performed in the background which does not affect the performance of
+   * tasks should be performed in the background which does not affect the performance of main
-	 * main thread.
+   * thread.
    */
   private ExecutorService service;
 
   /**
    * Creates an asynchronous service using {@code workQueue} as communication channel between
-	 * asynchronous layer and synchronous layer. Different types of queues such as Priority queue,
+   * asynchronous layer and synchronous layer. Different types of queues such as Priority queue, can
-	 * can be used to control the pattern of communication between the layers. 
+   * be used to control the pattern of communication between the layers.
    */
   public AsynchronousService(BlockingQueue<Runnable> workQueue) {
     service = new ThreadPoolExecutor(10, 10, 10, TimeUnit.SECONDS, workQueue);
@@ -38,8 +38,8 @@ public class AsynchronousService {
    * A non-blocking method which performs the task provided in background and returns immediately.
    * <p>
    * On successful completion of task the result is posted back using callback method
-	 * {@link AsyncTask#onPostCall(Object)}, if task execution is unable to complete normally
+   * {@link AsyncTask#onPostCall(Object)}, if task execution is unable to complete normally due to
-	 * due to some exception then the reason for error is posted back using callback method
+   * some exception then the reason for error is posted back using callback method
    * {@link AsyncTask#onError(Throwable)}.
    * <p>
    * NOTE: The results are posted back in the context of background thread in this implementation.
@@ -57,11 +57,11 @@ public class AsynchronousService {
       protected void done() {
         super.done();
         try {
-					/* called in context of background thread. There is other variant possible
+          /*
-					 * where result is posted back and sits in the queue of caller thread which
+           * called in context of background thread. There is other variant possible where result is
-					 * then picks it up for processing. An example of such a system is Android OS,
+           * posted back and sits in the queue of caller thread which then picks it up for
-					 * where the UI elements can only be updated using UI thread. So result must be
+           * processing. An example of such a system is Android OS, where the UI elements can only
-					 * posted back in UI thread.
+           * be updated using UI thread. So result must be posted back in UI thread.
            */
           task.onPostCall(get());
         } catch (InterruptedException e) {

intercepting-filter/src/main/java/com/iluwatar/intercepting/filter/AbstractFilter.java

@@ -1,16 +1,14 @@
 package com.iluwatar.intercepting.filter;
 
 /**
- * Base class for order processing filters.
+ * Base class for order processing filters. Handles chain management.
- * Handles chain management.
  *
  */
 public abstract class AbstractFilter implements Filter {
 
   private Filter next;
 
-	public AbstractFilter() {
+  public AbstractFilter() {}
-	}
 
   public AbstractFilter(Filter next) {
     this.next = next;

intercepting-filter/src/main/java/com/iluwatar/intercepting/filter/AddressFilter.java

@@ -1,8 +1,9 @@
 package com.iluwatar.intercepting.filter;
 
 /**
- * Concrete implementation of filter
+ * Concrete implementation of filter This filter is responsible for checking/filtering the input in
- * This filter is responsible for checking/filtering the input in the address field.
+ * the address field.
+ * 
  * @author joshzambales
  *
  */

intercepting-filter/src/main/java/com/iluwatar/intercepting/filter/App.java

@@ -2,39 +2,35 @@ package com.iluwatar.intercepting.filter;
 
 /**
  * 
- * When a request enters a Web application, it often must pass several entrance 
+ * When a request enters a Web application, it often must pass several entrance tests prior to the
- * tests prior to the main processing stage. For example,
+ * main processing stage. For example, - Has the client been authenticated? - Does the client have a
- * - Has the client been authenticated?
+ * valid session? - Is the client's IP address from a trusted network? - Does the request path
- * - Does the client have a valid session?
+ * violate any constraints? - What encoding does the client use to send the data? - Do we support
- * - Is the client's IP address from a trusted network?
+ * the browser type of the client? Some of these checks are tests, resulting in a yes or no answer
- * - Does the request path violate any constraints?
+ * that determines whether processing will continue. Other checks manipulate the incoming data
- * - What encoding does the client use to send the data?
- * - Do we support the browser type of the client?
- * Some of these checks are tests, resulting in a yes or no answer that determines 
- * whether processing will continue. Other checks manipulate the incoming data 
  * stream into a form suitable for processing.
  * <p>
- * The classic solution consists of a series of conditional checks, with any failed 
+ * The classic solution consists of a series of conditional checks, with any failed check aborting
- * check aborting the request. Nested if/else statements are a standard strategy, 
+ * the request. Nested if/else statements are a standard strategy, but this solution leads to code
- * but this solution leads to code fragility and a copy-and-paste style of programming, 
+ * fragility and a copy-and-paste style of programming, because the flow of the filtering and the
- * because the flow of the filtering and the action of the filters is compiled into 
+ * action of the filters is compiled into the application.
- * the application.
  * <p>
- * The key to solving this problem in a flexible and unobtrusive manner is to have a 
+ * The key to solving this problem in a flexible and unobtrusive manner is to have a simple
- * simple mechanism for adding and removing processing components, in which each 
+ * mechanism for adding and removing processing components, in which each component completes a
- * component completes a specific filtering action. This is the Intercepting Filter
+ * specific filtering action. This is the Intercepting Filter pattern in action.
- * pattern in action.
  * <p>
- * In this example we check whether the order request is valid through pre-processing 
+ * In this example we check whether the order request is valid through pre-processing done via
- * done via {@link Filter}. Each field has its own corresponding {@link Filter}
+ * {@link Filter}. Each field has its own corresponding {@link Filter}
  * <p>
+ * 
  * @author joshzambales
  *
  */
-public class App{
+public class App {
 
   /**
    * Program entry point
+   * 
    * @param args command line args
    */
   public static void main(String[] args) {

intercepting-filter/src/main/java/com/iluwatar/intercepting/filter/Client.java

@@ -15,9 +15,11 @@ import javax.swing.JTextField;
 import javax.swing.SwingUtilities;
 
 /**
- * The Client class is responsible for handling the input and running them through filters inside the {@link FilterManager}.
+ * The Client class is responsible for handling the input and running them through filters inside
+ * the {@link FilterManager}.
  *
- * This is where {@link Filter}s come to play as the client pre-processes the request before being displayed in the {@link Target}.
+ * This is where {@link Filter}s come to play as the client pre-processes the request before being
+ * displayed in the {@link Target}.
  * 
  * @author joshzambales
  *
@@ -85,8 +87,8 @@ public class Client extends JFrame {
     processButton.addActionListener(new ActionListener() {
       @Override
       public void actionPerformed(ActionEvent e) {
-				Order order = new Order(jtFields[0].getText(), jtFields[1]
+        Order order =
-						.getText(), jtAreas[0].getText(),
+            new Order(jtFields[0].getText(), jtFields[1].getText(), jtAreas[0].getText(),
                 jtFields[2].getText(), jtAreas[1].getText());
         jl.setText(sendRequest(order));
       }

intercepting-filter/src/main/java/com/iluwatar/intercepting/filter/ContactFilter.java

@@ -1,9 +1,10 @@
 package com.iluwatar.intercepting.filter;
 
 /**
- * Concrete implementation of filter
+ * Concrete implementation of filter This filter checks for the contact field in which it checks if
- * This filter checks for the contact field in which it checks if the input consist of numbers 
+ * the input consist of numbers and it also checks if the input follows the length constraint (11
- * and it also checks if the input follows the length constraint (11 digits)
+ * digits)
+ * 
  * @author joshzambales
  *
  */
@@ -12,8 +13,7 @@ public class ContactFilter extends AbstractFilter {
   @Override
   public String execute(Order order) {
     String result = super.execute(order);
-		if (order.getContactNumber() == null
+    if (order.getContactNumber() == null || order.getContactNumber().isEmpty()
-				|| order.getContactNumber().isEmpty()
         || order.getContactNumber().matches(".*[^\\d]+.*")
         || order.getContactNumber().length() != 11) {
       return result + "Invalid contact number! ";

intercepting-filter/src/main/java/com/iluwatar/intercepting/filter/DepositFilter.java

@@ -1,8 +1,8 @@
 package com.iluwatar.intercepting.filter;
 
 /**
- * Concrete implementation of filter
+ * Concrete implementation of filter This checks for the deposit code
- * This checks for the deposit code 
+ * 
  * @author joshzambales
  *
  */

intercepting-filter/src/main/java/com/iluwatar/intercepting/filter/Filter.java

@@ -1,9 +1,8 @@
 package com.iluwatar.intercepting.filter;
 
 /**
- * Filters perform certain tasks prior or after execution of
+ * Filters perform certain tasks prior or after execution of request by request handler. In this
- * request by request handler. In this case, before the request is handled by
+ * case, before the request is handled by the target, the request undergoes through each Filter
- * the target, the request undergoes through each Filter
  * 
  * @author joshzambales
  *
@@ -12,6 +11,7 @@ public interface Filter {
 
   /**
    * Execute order processing filter.
+   * 
    * @param order
    * @return empty string on success, otherwise error message.
    */
@@ -19,18 +19,21 @@ public interface Filter {
 
   /**
    * Set next filter in chain after this.
+   * 
    * @param filter
    */
   void setNext(Filter filter);
 
   /**
    * Get next filter in chain after this.
+   * 
    * @return
    */
   Filter getNext();
 
   /**
    * Get last filter in the chain.
+   * 
    * @return
    */
   Filter getLast();

intercepting-filter/src/main/java/com/iluwatar/intercepting/filter/FilterChain.java

@@ -1,4 +1,4 @@
- package com.iluwatar.intercepting.filter;
+package com.iluwatar.intercepting.filter;
 
 
 /**

intercepting-filter/src/main/java/com/iluwatar/intercepting/filter/NameFilter.java

@@ -1,8 +1,8 @@
 package com.iluwatar.intercepting.filter;
 
 /**
- * Concrete implementation of filter. This filter checks if the input in the Name
+ * Concrete implementation of filter. This filter checks if the input in the Name field is valid.
- * field is valid. (alphanumeric)
+ * (alphanumeric)
  * 
  * @author joshzambales
  *
@@ -12,7 +12,8 @@ public class NameFilter extends AbstractFilter {
   @Override
   public String execute(Order order) {
     String result = super.execute(order);
-		if (order.getName() == null || order.getName().isEmpty() || order.getName().matches(".*[^\\w|\\s]+.*")) {
+    if (order.getName() == null || order.getName().isEmpty()
+        || order.getName().matches(".*[^\\w|\\s]+.*")) {
       return result + "Invalid order! ";
     } else {
       return result;

intercepting-filter/src/main/java/com/iluwatar/intercepting/filter/Order.java

@@ -12,8 +12,7 @@ public class Order {
   private String depositNumber;
   private String order;
 
-	public Order() {
+  public Order() {}
-	}
 
   public Order(String name, String contactNumber, String address, String depositNumber, String order) {
     this.name = name;

intercepting-filter/src/main/java/com/iluwatar/intercepting/filter/Target.java

@@ -33,8 +33,9 @@ public class Target extends JFrame {
     super("Order System");
     setDefaultCloseOperation(EXIT_ON_CLOSE);
     setSize(640, 480);
-		dtm = new DefaultTableModel(new Object[] { "Name", "Contact Number",
+    dtm =
-				"Address", "Deposit Number", "Order" }, 0);
+        new DefaultTableModel(new Object[] {"Name", "Contact Number", "Address", "Deposit Number",
+            "Order"}, 0);
     jt = new JTable(dtm);
     del = new JButton("Delete");
     setup();
@@ -59,8 +60,7 @@ public class Target extends JFrame {
   }
 
   public void execute(String[] request) {
-		dtm.addRow(new Object[] { request[0], request[1], request[2],
+    dtm.addRow(new Object[] {request[0], request[1], request[2], request[3], request[4]});
-				request[3], request[4] });
   }
 
   class DListener implements ActionListener {

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

@@ -4,14 +4,13 @@ import java.util.Stack;
 
 /**
  * 
- * The Interpreter pattern is a design pattern that specifies how to evaluate sentences 
+ * The Interpreter pattern is a design pattern that specifies how to evaluate sentences in a
- * in a language. The basic idea is to have a class for each symbol (terminal or nonterminal) 
+ * language. The basic idea is to have a class for each symbol (terminal or nonterminal) in a
- * in a specialized computer language. The syntax tree of a sentence in the language is an 
+ * specialized computer language. The syntax tree of a sentence in the language is an instance of
- * instance of the composite pattern and is used to evaluate (interpret) the sentence for a 
+ * the composite pattern and is used to evaluate (interpret) the sentence for a client.
- * client.
  * <p>
- * In this example we use the Interpreter pattern to break sentences into expressions 
+ * In this example we use the Interpreter pattern to break sentences into expressions (
- * ({@link Expression}) that can be evaluated and as a whole form the result.
+ * {@link Expression}) that can be evaluated and as a whole form the result.
  * 
  */
 public class App {
@@ -20,8 +19,8 @@ public class App {
    * 
    * Program entry point.
    * <p>
-	 * Expressions can be evaluated using prefix, infix or postfix notations
+   * Expressions can be evaluated using prefix, infix or postfix notations This sample uses postfix,
-	 * This sample uses postfix, where operator comes after the operands
+   * where operator comes after the operands
    * 
    * @param args command line args
    * 
@@ -35,36 +34,28 @@ public class App {
       if (isOperator(s)) {
         Expression rightExpression = stack.pop();
         Expression leftExpression = stack.pop();
-				System.out
+        System.out.println(String.format("popped from stack left: %d right: %d",
-						.println(String.format(
+            leftExpression.interpret(), rightExpression.interpret()));
-								"popped from stack left: %d right: %d",
+        Expression operator = getOperatorInstance(s, leftExpression, rightExpression);
-								leftExpression.interpret(),
-								rightExpression.interpret()));
-				Expression operator = getOperatorInstance(s, leftExpression,
-						rightExpression);
         System.out.println(String.format("operator: %s", operator));
         int result = operator.interpret();
         NumberExpression resultExpression = new NumberExpression(result);
         stack.push(resultExpression);
-				System.out.println(String.format("push result to stack: %d",
+        System.out.println(String.format("push result to stack: %d", resultExpression.interpret()));
-						resultExpression.interpret()));
       } else {
         Expression i = new NumberExpression(s);
         stack.push(i);
-				System.out.println(String.format("push to stack: %d",
+        System.out.println(String.format("push to stack: %d", i.interpret()));
-						i.interpret()));
       }
     }
-		System.out
+    System.out.println(String.format("result: %d", stack.pop().interpret()));
-				.println(String.format("result: %d", stack.pop().interpret()));
   }
 
   public static boolean isOperator(String s) {
     return s.equals("+") || s.equals("-") || s.equals("*");
   }
 
-	public static Expression getOperatorInstance(String s, Expression left,
+  public static Expression getOperatorInstance(String s, Expression left, Expression right) {
-			Expression right) {
     switch (s) {
       case "+":
         return new PlusExpression(left, right);

interpreter/src/main/java/com/iluwatar/interpreter/MultiplyExpression.java

@@ -10,8 +10,7 @@ public class MultiplyExpression extends Expression {
   private Expression leftExpression;
   private Expression rightExpression;
 
-	public MultiplyExpression(Expression leftExpression,
+  public MultiplyExpression(Expression leftExpression, Expression rightExpression) {
-			Expression rightExpression) {
     this.leftExpression = leftExpression;
     this.rightExpression = rightExpression;
   }