Resolves checkstyle errors for delegation dependency-injection dirty-flag double-buffer double-checked-locking double-dispatch (#1068)

* Reduces checkstyle errors in delegation

* Reduces checkstyle errors in dependency-injection

* Reduces checkstyle errors in dirty-flag

* Reduces checkstyle errors in double-buffer

* Reduces checkstyle errors in double-checked-locking

* Reduces checkstyle errors in double-dispatch

delegation/src/main/java/com/iluwatar/delegation/simple/App.java

@@ -28,23 +28,25 @@ import com.iluwatar.delegation.simple.printers.EpsonPrinter;
 import com.iluwatar.delegation.simple.printers.HpPrinter;
 
 /**
- * The delegate pattern provides a mechanism to abstract away the implementation and control of the desired action.
+ * The delegate pattern provides a mechanism to abstract away the implementation and control of the
- * The class being called in this case {@link PrinterController} is not responsible for the actual desired action,
+ * desired action. The class being called in this case {@link PrinterController} is not responsible
- * but is actually delegated to a helper class either {@link CanonPrinter}, {@link EpsonPrinter} or {@link HpPrinter}.
+ * for the actual desired action, but is actually delegated to a helper class either {@link
- * The consumer does not have or require knowledge of the actual class carrying out the action, only the
+ * CanonPrinter}, {@link EpsonPrinter} or {@link HpPrinter}. The consumer does not have or require
- * container on which they are calling.
+ * knowledge of the actual class carrying out the action, only the container on which they are
+ * calling.
  *
- * In this example the delegates are {@link EpsonPrinter}, {@link HpPrinter} and {@link CanonPrinter} they all implement
+ * <p>In this example the delegates are {@link EpsonPrinter}, {@link HpPrinter} and {@link
- * {@link Printer}. The {@link PrinterController} class also implements {@link Printer}. However neither provide the
+ * CanonPrinter} they all implement {@link Printer}. The {@link PrinterController} class also
- * functionality of {@link Printer} by printing to the screen, they actually call upon the instance of {@link Printer}
+ * implements {@link Printer}. However neither provide the functionality of {@link Printer} by
- * that they were instantiated with. Therefore delegating the behaviour to another class.
+ * printing to the screen, they actually call upon the instance of {@link Printer} that they were
+ * instantiated with. Therefore delegating the behaviour to another class.
  */
 public class App {
 
   private static final String MESSAGE_TO_PRINT = "hello world";
 
   /**
-   * Program entry point
+   * Program entry point.
    *
    * @param args command line args
    */

delegation/src/main/java/com/iluwatar/delegation/simple/Printer.java

@@ -38,7 +38,8 @@ public interface Printer {
 
   /**
    * Method that takes a String to print to the screen. This will be implemented on both the
-   * controller and the delegate allowing the controller to call the same method on the delegate class.
+   * controller and the delegate allowing the controller to call the same method on the delegate
+   * class.
    *
    * @param message to be printed to the screen
    */

delegation/src/main/java/com/iluwatar/delegation/simple/PrinterController.java

@@ -24,10 +24,10 @@
 package com.iluwatar.delegation.simple;
 
 /**
- * Delegator Class to delegate the implementation of the Printer.
+ * Delegator Class to delegate the implementation of the Printer. This ensures two things: - when
- * This ensures two things:
+ * the actual implementation of the Printer class changes the delegation will still be operational -
- *  - when the actual implementation of the Printer class changes the delegation will still be operational
+ * the actual benefit is observed when there are more than one implementors and they share a
- *  - the actual benefit is observed when there are more than one implementors and they share a delegation control
+ * delegation control
  */
 public class PrinterController implements Printer {
 
@@ -38,10 +38,10 @@ public class PrinterController implements Printer {
   }
 
   /**
-   * This method is implemented from {@link Printer} however instead on providing an
+   * This method is implemented from {@link Printer} however instead on providing an implementation,
-   * implementation, it instead calls upon the class passed through the constructor. This is the delegate,
+   * it instead calls upon the class passed through the constructor. This is the delegate, hence the
-   * hence the pattern. Therefore meaning that the caller does not care of the implementing class only the owning
+   * pattern. Therefore meaning that the caller does not care of the implementing class only the
-   * controller.
+   * owning controller.
    *
    * @param message to be printed to the screen
    */

delegation/src/main/java/com/iluwatar/delegation/simple/printers/CanonPrinter.java

@@ -28,8 +28,8 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 /**
- * Specialised Implementation of {@link Printer} for a Canon Printer, in
+ * Specialised Implementation of {@link Printer} for a Canon Printer, in this case the message to be
- * this case the message to be printed is appended to "Canon Printer : "
+ * printed is appended to "Canon Printer : ".
  *
  * @see Printer
  */

delegation/src/main/java/com/iluwatar/delegation/simple/printers/EpsonPrinter.java

@@ -28,8 +28,8 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 /**
- * Specialised Implementation of {@link Printer} for a Epson Printer, in
+ * Specialised Implementation of {@link Printer} for a Epson Printer, in this case the message to be
- * this case the message to be printed is appended to "Epson Printer : "
+ * printed is appended to "Epson Printer : ".
  *
  * @see Printer
  */

delegation/src/main/java/com/iluwatar/delegation/simple/printers/HpPrinter.java

@@ -28,8 +28,8 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 /**
- * Specialised Implementation of {@link Printer} for a HP Printer, in
+ * Specialised Implementation of {@link Printer} for a HP Printer, in this case the message to be
- * this case the message to be printed is appended to "HP Printer : "
+ * printed is appended to "HP Printer : ".
  *
  * @see Printer
  */

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

@@ -23,30 +23,6 @@
 
 package com.iluwatar.dependency.injection;
 
-/**
- * The MIT License
- * Copyright (c) 2014-2017 Ilkka Seppälä
- * <p>
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- * <p>
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- * <p>
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- * THE SOFTWARE.
- */
-
-
 /**
  * AdvancedSorceress implements inversion of control. It depends on abstraction that can be injected
  * through its setter.

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

@@ -24,10 +24,8 @@
 package com.iluwatar.dependency.injection;
 
 /**
- * 
  * AdvancedWizard implements inversion of control. It depends on abstraction that can be injected
  * through its constructor.
- *
  */
 public class AdvancedWizard implements Wizard {
 

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

@@ -31,25 +31,26 @@ import com.google.inject.Injector;
  * implements so called inversion of control principle. Inversion of control has two specific rules:
  * - High-level modules should not depend on low-level modules. Both should depend on abstractions.
  * - 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
+ * <p>In this example we show you three different wizards. The first one ({@link SimpleWizard}) is
- * naive implementation violating the inversion of control principle. It depends directly on a
+ * a naive implementation violating the inversion of control principle. It depends directly on a
  * concrete implementation which cannot be changed.
- * <p>
+ *
- * The second and third wizards({@link AdvancedWizard} and {@link AdvancedSorceress}) are more flexible.
+ * <p>The second and third wizards({@link AdvancedWizard} and {@link AdvancedSorceress}) are more
- * They do not depend on any concrete implementation but abstraction. They utilizes Dependency Injection
+ * flexible. They do not depend on any concrete implementation but abstraction. They utilizes
- * pattern allowing their {@link Tobacco} dependency to be injected through constructor ({@link AdvancedWizard})
+ * Dependency Injection pattern allowing their {@link Tobacco} dependency to be injected through
- * or setter ({@link AdvancedSorceress}). This way, handling the dependency is no longer the wizard's
+ * constructor ({@link AdvancedWizard}) or setter ({@link AdvancedSorceress}). This way, handling
- * responsibility. It is resolved outside the wizard class.
+ * the dependency is no longer the wizard's responsibility. It is resolved outside the wizard
- * <p>
+ * class.
- * The fourth example takes the pattern a step further. It uses Guice framework for Dependency
+ *
+ * <p>The fourth example takes the pattern a step further. It uses Guice framework for Dependency
  * Injection. {@link TobaccoModule} binds a concrete implementation to abstraction. Injector is then
  * used to create {@link GuiceWizard} object with correct dependencies.
  */
 public class App {
 
   /**
-   * Program entry point
+   * Program entry point.
    *
    * @param args command line args
    */

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

@@ -26,10 +26,8 @@ package com.iluwatar.dependency.injection;
 import javax.inject.Inject;
 
 /**
- * 
  * GuiceWizard implements inversion of control. Its dependencies are injected through its
  * constructor by Guice framework.
- *
  */
 public class GuiceWizard implements Wizard {
 

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

@@ -24,9 +24,7 @@
 package com.iluwatar.dependency.injection;
 
 /**
- * 
+ * OldTobyTobacco concrete {@link Tobacco} implementation.
- * OldTobyTobacco concrete {@link Tobacco} implementation
- *
  */
 public class OldTobyTobacco extends Tobacco {
 }

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

@@ -24,9 +24,7 @@
 package com.iluwatar.dependency.injection;
 
 /**
- * 
+ * RivendellTobacco concrete {@link Tobacco} implementation.
- * RivendellTobacco concrete {@link Tobacco} implementation
- *
  */
 public class RivendellTobacco extends Tobacco {
 }

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

@@ -24,9 +24,7 @@
 package com.iluwatar.dependency.injection;
 
 /**
- * 
+ * SecondBreakfastTobacco concrete {@link Tobacco} implementation.
- * SecondBreakfastTobacco concrete {@link Tobacco} implementation
- *
  */
 public class SecondBreakfastTobacco extends Tobacco {
 }

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

@@ -24,10 +24,8 @@
 package com.iluwatar.dependency.injection;
 
 /**
- * 
  * Naive Wizard implementation violating the inversion of control principle. It should depend on
  * abstraction instead.
- *
  */
 public class SimpleWizard implements Wizard {
 

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

@@ -27,9 +27,7 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 /**
- * 
+ * Tobacco abstraction.
- * Tobacco abstraction
- *
  */
 public abstract class Tobacco {
 

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

@@ -26,9 +26,7 @@ package com.iluwatar.dependency.injection;
 import com.google.inject.AbstractModule;
 
 /**
- * 
  * Guice module for binding certain concrete {@link Tobacco} implementation.
- *
  */
 public class TobaccoModule extends AbstractModule {
 

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

@@ -24,9 +24,7 @@
 package com.iluwatar.dependency.injection;
 
 /**
- * 
+ * Wizard interface.
- * Wizard interface
- *
  */
 public interface Wizard {
 

dirty-flag/src/main/java/com/iluwatar/dirtyflag/App.java

@@ -23,45 +23,49 @@
 
 package com.iluwatar.dirtyflag;
 
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
 import java.util.List;
 import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
+ * This application demonstrates the <b>Dirty Flag</b> pattern. The dirty flag behavioral pattern
+ * allows you to avoid expensive operations that would just need to be done again anyway. This is a
+ * simple pattern that really just explains how to add a bool value to your class that you can set
+ * anytime a property changes. This will let your class know that any results it may have previously
+ * calculated will need to be calculated again when they’re requested. Once the results are
+ * re-calculated, then the bool value can be cleared.
  *
- * This application demonstrates the <b>Dirty Flag</b> pattern. The dirty flag behavioral pattern allows you to avoid
+ * <p>There are some points that need to be considered before diving into using this pattern:-
- * expensive operations that would just need to be done again anyway. This is a simple pattern that really just explains
+ * there are some things you’ll need to consider:- (1) Do you need it? This design pattern works
- * how to add a bool value to your class that you can set anytime a property changes. This will let your class know that
+ * well when the results to be calculated are difficult or resource intensive to compute. You want
- * any results it may have previously calculated will need to be calculated again when they’re requested. Once the
+ * to save them. You also don’t want to be calculating them several times in a row when only the
- * results are re-calculated, then the bool value can be cleared.
+ * last one counts. (2) When do you set the dirty flag? Make sure that you set the dirty flag within
+ * the class itself whenever an important property changes. This property should affect the result
+ * of the calculated result and by changing the property, that makes the last result invalid. (3)
+ * When do you clear the dirty flag? It might seem obvious that the dirty flag should be cleared
+ * whenever the result is calculated with up-to-date information but there are other times when you
+ * might want to clear the flag.
  *
- * There are some points that need to be considered before diving into using this pattern:- there are some things you’ll
+ * <p>In this example, the {@link DataFetcher} holds the <i>dirty flag</i>. It fetches and
- * need to consider:- (1) Do you need it? This design pattern works well when the results to be calculated are difficult
+ * re-fetches from <i>world.txt</i> when needed. {@link World} mainly serves the data to the
- * or resource intensive to compute. You want to save them. You also don’t want to be calculating them several times in
+ * front-end.
- * a row when only the last one counts. (2) When do you set the dirty flag? Make sure that you set the dirty flag within
- * the class itself whenever an important property changes. This property should affect the result of the calculated
- * result and by changing the property, that makes the last result invalid. (3) When do you clear the dirty flag? It
- * might seem obvious that the dirty flag should be cleared whenever the result is calculated with up-to-date
- * information but there are other times when you might want to clear the flag.
- *
- * In this example, the {@link DataFetcher} holds the <i>dirty flag</i>. It fetches and re-fetches from <i>world.txt</i>
- * when needed. {@link World} mainly serves the data to the front-end.
  */
 public class App {
 
   private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
+
   /**
-   * Program execution point
+   * Program execution point.
    */
   public void run() {
 
     final ScheduledExecutorService executorService = Executors.newSingleThreadScheduledExecutor();
     executorService.scheduleAtFixedRate(new Runnable() {
       final World world = new World();
+
       @Override
       public void run() {
         List<String> countries = world.fetch();
@@ -74,10 +78,9 @@ public class App {
   }
 
   /**
-   * Program entry point
+   * Program entry point.
    *
-   * @param args
+   * @param args command line args
-   *          command line args
    */
   public static void main(String[] args) {
     App app = new App();

dirty-flag/src/main/java/com/iluwatar/dirtyflag/DataFetcher.java

@@ -23,22 +23,19 @@
 
 package com.iluwatar.dirtyflag;
 
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
-import javax.xml.crypto.Data;
 import java.io.BufferedReader;
 import java.io.File;
 import java.io.FileReader;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
  * A mock database manager -- Fetches data from a raw file.
  *
  * @author swaisuan
- *
  */
 public class DataFetcher {
 

dirty-flag/src/main/java/com/iluwatar/dirtyflag/World.java

@@ -27,11 +27,9 @@ import java.util.ArrayList;
 import java.util.List;
 
 /**
- * 
  * A middle-layer app that calls/passes along data from the back-end.
  *
  * @author swaisuan
- *
  */
 public class World {
 
@@ -44,7 +42,6 @@ public class World {
   }
 
   /**
-   * 
    * Calls {@link DataFetcher} to fetch data from back-end.
    *
    * @return List of strings

double-buffer/src/main/java/com/iluwatar/doublebuffer/App.java

@@ -23,21 +23,19 @@
 
 package com.iluwatar.doublebuffer;
 
+import java.util.ArrayList;
+import java.util.List;
 import org.apache.commons.lang3.tuple.MutablePair;
 import org.apache.commons.lang3.tuple.Pair;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import java.util.ArrayList;
-import java.util.List;
-
 /**
- * Double buffering is a term used to describe a device that has two buffers.
+ * Double buffering is a term used to describe a device that has two buffers. The usage of multiple
- * The usage of multiple buffers increases the overall throughput of a device
+ * buffers increases the overall throughput of a device and helps prevents bottlenecks. This example
- * and helps prevents bottlenecks. This example shows using double buffer pattern
+ * shows using double buffer pattern on graphics. It is used to show one image or frame while a
- * on graphics. It is used to show one image or frame while a separate frame
+ * separate frame is being buffered to be shown next. This method makes animations and games look
- * is being buffered to be shown next. This method makes animations and games
+ * more realistic than the same done in a single buffer mode.
- * look more realistic than the same done in a single buffer mode.
  */
 public class App {
 
@@ -45,10 +43,11 @@ public class App {
 
   /**
    * Program main entry point.
+   *
    * @param args runtime arguments
    */
   public static void main(String[] args) {
-    var scene = new Scene();
+    final var scene = new Scene();
     List<Pair<Integer, Integer>> drawPixels = new ArrayList<>();
     Pair<Integer, Integer> pixel1 = new MutablePair<>(1, 1);
     Pair<Integer, Integer> pixel2 = new MutablePair<>(5, 6);

double-buffer/src/main/java/com/iluwatar/doublebuffer/Buffer.java

@@ -30,6 +30,7 @@ public interface Buffer {
 
   /**
    * Clear the pixel in (x, y).
+   *
    * @param x X coordinate
    * @param y Y coordinate
    */
@@ -37,6 +38,7 @@ public interface Buffer {
 
   /**
    * Draw the pixel in (x, y).
+   *
    * @param x X coordinate
    * @param y Y coordinate
    */
@@ -49,6 +51,7 @@ public interface Buffer {
 
   /**
    * Get all the pixels.
+   *
    * @return pixel list
    */
   Pixel[] getPixels();

double-buffer/src/main/java/com/iluwatar/doublebuffer/FrameBuffer.java

@@ -23,9 +23,6 @@
 
 package com.iluwatar.doublebuffer;
 
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
 /**
  * FrameBuffer implementation class.
  */

double-buffer/src/main/java/com/iluwatar/doublebuffer/Scene.java

@@ -23,12 +23,11 @@
 
 package com.iluwatar.doublebuffer;
 
+import java.util.List;
 import org.apache.commons.lang3.tuple.Pair;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import java.util.List;
-
 /**
  * Scene class. Render the output frame.
  */
@@ -55,6 +54,7 @@ public class Scene {
 
   /**
    * Draw the next frame.
+   *
    * @param coordinateList list of pixels of which the color should be black
    */
   public void draw(List<Pair<Integer, Integer>> coordinateList) {

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

@@ -23,31 +23,29 @@
 
 package com.iluwatar.doublechecked.locking;
 
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.TimeUnit;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
- * 
  * Double Checked Locking is a concurrency design pattern used to reduce the overhead of acquiring a
  * lock by first testing the locking criterion (the "lock hint") without actually acquiring the
  * lock. Only if the locking criterion check indicates that locking is required does the actual
  * locking logic proceed.
- * <p>
- * In {@link Inventory} we store the items with a given size. However, we do not store more items
- * than the inventory size. To address concurrent access problems we use double checked locking to
- * add item to inventory. In this method, the thread which gets the lock first adds the item.
  *
+ * <p>In {@link Inventory} we store the items with a given size. However, we do not store more
+ * items than the inventory size. To address concurrent access problems we use double checked
+ * locking to add item to inventory. In this method, the thread which gets the lock first adds the
+ * item.
  */
 public class App {
 
   private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
 
   /**
-   * Program entry point
+   * Program entry point.
    *
    * @param args command line args
    */

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

@@ -23,19 +23,16 @@
 
 package com.iluwatar.doublechecked.locking;
 
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 import java.util.concurrent.locks.Lock;
 import java.util.concurrent.locks.ReentrantLock;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
- * 
+ * Inventory.
- * Inventory
- *
  */
 public class Inventory {
 
@@ -46,7 +43,7 @@ public class Inventory {
   private final Lock lock;
 
   /**
-   * Constructor
+   * Constructor.
    */
   public Inventory(int inventorySize) {
     this.inventorySize = inventorySize;
@@ -55,7 +52,7 @@ public class Inventory {
   }
 
   /**
-   * Add item
+   * Add item.
    */
   public boolean addItem(Item item) {
     if (items.size() < inventorySize) {
@@ -63,7 +60,8 @@ public class Inventory {
       try {
         if (items.size() < inventorySize) {
           items.add(item);
-          LOGGER.info("{}: items.size()={}, inventorySize={}", Thread.currentThread(), items.size(), inventorySize);
+          LOGGER.info("{}: items.size()={}, inventorySize={}", Thread.currentThread(), items
+              .size(), inventorySize);
           return true;
         }
       } finally {
@@ -74,7 +72,7 @@ public class Inventory {
   }
 
   /**
-   * Get all the items in the inventory
+   * Get all the items in the inventory.
    *
    * @return All the items of the inventory, as an unmodifiable list
    */

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

@@ -24,9 +24,7 @@
 package com.iluwatar.doublechecked.locking;
 
 /**
- * 
+ * Item.
- * Item
- *
  */
 public class Item {
 }

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

@@ -23,38 +23,37 @@
 
 package com.iluwatar.doubledispatch;
 
+import java.util.List;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-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 by
+ * the type of the parameter.
  *
- * When a message with a parameter is sent to an object, the resultant behaviour is defined by the implementation of
+ * <p>One way to implement this would be to create multiple instanceof-checks for the methods
- * that method in the receiver. Sometimes the behaviour must also be determined by the type of the parameter.
+ * parameter. However, this creates a maintenance issue. When new types are added we would also need
- * <p>
+ * to change the method's implementation and add a new instanceof-check. This violates the single
- * One way to implement this would be to create multiple instanceof-checks for the methods parameter. However, this
+ * responsibility principle - a class should have only one reason to change.
- * creates a maintenance issue. When new types are added we would also need to change the method's implementation and
- * add a new instanceof-check. This violates the single 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 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.
  *
+ * <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 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.
  */
 public class App {
 
   private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
 
   /**
-   * Program entry point
+   * Program entry point.
    *
-   * @param args
+   * @param args command line args
-   *          command line args
    */
   public static void main(String[] args) {
     // initialize game objects and print their status

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

@@ -24,9 +24,7 @@
 package com.iluwatar.doubledispatch;
 
 /**
- * 
+ * Flaming asteroid game object.
- * Flaming asteroid game object
- *
  */
 public class FlamingAsteroid extends Meteoroid {
 

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

@@ -24,9 +24,7 @@
 package com.iluwatar.doubledispatch;
 
 /**
- * 
  * Game objects have coordinates and some other status information.
- *
  */
 public abstract class GameObject extends Rectangle {
 

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

@@ -23,15 +23,12 @@
 
 package com.iluwatar.doubledispatch;
 
+import com.iluwatar.doubledispatch.constants.AppConstants;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import com.iluwatar.doubledispatch.constants.AppConstants;
-
 /**
- * 
+ * Meteoroid game object.
- * Meteoroid game object
- *
  */
 public class Meteoroid extends GameObject {
 
@@ -48,12 +45,14 @@ public class Meteoroid extends GameObject {
 
   @Override
   public void collisionResolve(FlamingAsteroid asteroid) {
-    LOGGER.info(AppConstants.HITS, asteroid.getClass().getSimpleName(), this.getClass().getSimpleName());
+    LOGGER.info(AppConstants.HITS, asteroid.getClass().getSimpleName(), this.getClass()
+        .getSimpleName());
   }
 
   @Override
   public void collisionResolve(Meteoroid meteoroid) {
-    LOGGER.info(AppConstants.HITS, meteoroid.getClass().getSimpleName(), this.getClass().getSimpleName());
+    LOGGER.info(AppConstants.HITS, meteoroid.getClass().getSimpleName(), this.getClass()
+        .getSimpleName());
   }
 
   @Override

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

@@ -24,9 +24,7 @@
 package com.iluwatar.doubledispatch;
 
 /**
- * 
  * Rectangle has coordinates and can be checked for overlap against other Rectangles.
- *
  */
 public class Rectangle {
 
@@ -36,7 +34,7 @@ public class Rectangle {
   private int bottom;
 
   /**
-   * Constructor
+   * Constructor.
    */
   public Rectangle(int left, int top, int right, int bottom) {
     this.left = left;

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

@@ -24,9 +24,7 @@
 package com.iluwatar.doubledispatch;
 
 /**
- * 
+ * Space station ISS game object.
- * Space station ISS game object
- *
  */
 public class SpaceStationIss extends SpaceStationMir {
 

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

@@ -23,15 +23,12 @@
 
 package com.iluwatar.doubledispatch;
 
+import com.iluwatar.doubledispatch.constants.AppConstants;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import com.iluwatar.doubledispatch.constants.AppConstants;
-
 /**
- * 
+ * Space station Mir game object.
- * Space station Mir game object
- *
  */
 public class SpaceStationMir extends GameObject {
 
@@ -48,29 +45,31 @@ public class SpaceStationMir extends GameObject {
 
   @Override
   public void collisionResolve(FlamingAsteroid asteroid) {
-    LOGGER.info(AppConstants.HITS," {} is damaged! {} is set on fire!", asteroid.getClass().getSimpleName(),
+    LOGGER.info(AppConstants.HITS, " {} is damaged! {} is set on fire!", asteroid.getClass()
-        this.getClass().getSimpleName(), this.getClass().getSimpleName(), this.getClass().getSimpleName());
+            .getSimpleName(),
+        this.getClass().getSimpleName(), this.getClass().getSimpleName(), this.getClass()
+            .getSimpleName());
     setDamaged(true);
     setOnFire(true);
   }
 
   @Override
   public void collisionResolve(Meteoroid meteoroid) {
-    LOGGER.info(AppConstants.HITS," {} is damaged!", meteoroid.getClass().getSimpleName(),
+    LOGGER.info(AppConstants.HITS, " {} is damaged!", meteoroid.getClass().getSimpleName(),
         this.getClass().getSimpleName(), this.getClass().getSimpleName());
     setDamaged(true);
   }
 
   @Override
   public void collisionResolve(SpaceStationMir mir) {
-    LOGGER.info(AppConstants.HITS," {} is damaged!", mir.getClass().getSimpleName(),
+    LOGGER.info(AppConstants.HITS, " {} is damaged!", mir.getClass().getSimpleName(),
         this.getClass().getSimpleName(), this.getClass().getSimpleName());
     setDamaged(true);
   }
 
   @Override
   public void collisionResolve(SpaceStationIss iss) {
-    LOGGER.info(AppConstants.HITS," {} is damaged!", iss.getClass().getSimpleName(),
+    LOGGER.info(AppConstants.HITS, " {} is damaged!", iss.getClass().getSimpleName(),
         this.getClass().getSimpleName(), this.getClass().getSimpleName());
     setDamaged(true);
   }

double-dispatch/src/main/java/com/iluwatar/doubledispatch/constants/AppConstants.java

@@ -24,9 +24,7 @@
 package com.iluwatar.doubledispatch.constants;
 
 /**
- * 
+ * Constants class to define all constants.
- * Constants class to define all constants
- *
  */
 public class AppConstants {