checkstyle fixes - docs, indent etc

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

@@ -1,3 +1,6 @@
+/**
+ * Singleton pattern.
+ */
 package com.iluwatar.singleton;
 
 /**
@@ -16,40 +19,40 @@ package com.iluwatar.singleton;
  */
 public class App {
 
-	/**
+    /**
-	 * Program entry point
+     * Program entry point
-	 * @param args command line args
+     * @param args command line args
-	 */
+     */
-	public static void main(String[] args) {
+    public static void main(String[] args) {
 
-		// eagerly initialized singleton
+        // eagerly initialized singleton
-		IvoryTower ivoryTower1 = IvoryTower.getInstance();
+        IvoryTower ivoryTower1 = IvoryTower.getInstance();
-		IvoryTower ivoryTower2 = IvoryTower.getInstance();
+        IvoryTower ivoryTower2 = IvoryTower.getInstance();
-		System.out.println("ivoryTower1=" + ivoryTower1);
+        System.out.println("ivoryTower1=" + ivoryTower1);
-		System.out.println("ivoryTower2=" + ivoryTower2);
+        System.out.println("ivoryTower2=" + ivoryTower2);
 
-		// lazily initialized singleton
+        // lazily initialized singleton
-		ThreadSafeLazyLoadedIvoryTower threadSafeIvoryTower1 = ThreadSafeLazyLoadedIvoryTower
+        ThreadSafeLazyLoadedIvoryTower threadSafeIvoryTower1 = ThreadSafeLazyLoadedIvoryTower
-				.getInstance();
+                .getInstance();
-		ThreadSafeLazyLoadedIvoryTower threadSafeIvoryTower2 = ThreadSafeLazyLoadedIvoryTower
+        ThreadSafeLazyLoadedIvoryTower threadSafeIvoryTower2 = ThreadSafeLazyLoadedIvoryTower
-				.getInstance();
+                .getInstance();
-		System.out.println("threadSafeIvoryTower1=" + threadSafeIvoryTower1);
+        System.out.println("threadSafeIvoryTower1=" + threadSafeIvoryTower1);
-		System.out.println("threadSafeIvoryTower2=" + threadSafeIvoryTower2);
+        System.out.println("threadSafeIvoryTower2=" + threadSafeIvoryTower2);
 
-		// enum singleton
+        // enum singleton
-		EnumIvoryTower enumIvoryTower1 = EnumIvoryTower.INSTANCE;
+        EnumIvoryTower enumIvoryTower1 = EnumIvoryTower.INSTANCE;
-		EnumIvoryTower enumIvoryTower2 = EnumIvoryTower.INSTANCE;
+        EnumIvoryTower enumIvoryTower2 = EnumIvoryTower.INSTANCE;
-		System.out.println("enumIvoryTower1=" + enumIvoryTower1);
+        System.out.println("enumIvoryTower1=" + enumIvoryTower1);
-		System.out.println("enumIvoryTower2=" + enumIvoryTower2);
+        System.out.println("enumIvoryTower2=" + enumIvoryTower2);
 
-		InitializingOnDemandHolderIdiom demandHolderIdiom = InitializingOnDemandHolderIdiom.getInstance();
+        InitializingOnDemandHolderIdiom demandHolderIdiom = InitializingOnDemandHolderIdiom.getInstance();
-		System.out.println(demandHolderIdiom);
+        System.out.println(demandHolderIdiom);
-		InitializingOnDemandHolderIdiom demandHolderIdiom2 = InitializingOnDemandHolderIdiom.getInstance();
+        InitializingOnDemandHolderIdiom demandHolderIdiom2 = InitializingOnDemandHolderIdiom.getInstance();
-		System.out.println(demandHolderIdiom2);
+        System.out.println(demandHolderIdiom2);
 
-		ThreadSafeDoubleCheckLocking dcl1 = ThreadSafeDoubleCheckLocking.getInstance();
+        ThreadSafeDoubleCheckLocking dcl1 = ThreadSafeDoubleCheckLocking.getInstance();
-		System.out.println(dcl1);
+        System.out.println(dcl1);
-		ThreadSafeDoubleCheckLocking dcl2 = ThreadSafeDoubleCheckLocking.getInstance();
+        ThreadSafeDoubleCheckLocking dcl2 = ThreadSafeDoubleCheckLocking.getInstance();
-		System.out.println(dcl2);
+        System.out.println(dcl2);
-	}
+    }
 }

singleton/src/main/java/com/iluwatar/singleton/EnumIvoryTower.java

@@ -1,10 +1,11 @@
+/**
+ * Enum Singleton class.
+ * Effective Java 2nd Edition (Joshua Bloch) p. 18
+ */
 package com.iluwatar.singleton;
 
 /**
- *
+ * Enum based singleton implementation.
- * Enum Singleton class.
- * Effective Java 2nd Edition (Joshua Bloch) p. 18
- *
  */
 public enum EnumIvoryTower {
 

singleton/src/main/java/com/iluwatar/singleton/InitializingOnDemandHolderIdiom.java

@@ -1,3 +1,6 @@
+/**
+ * Singleton pattern.
+ */
 package com.iluwatar.singleton;
 
 import java.io.Serializable;
@@ -7,30 +10,29 @@ import java.io.Serializable;
  * creating lazy initialized singleton object in Java.
  * refer to "The CERT Oracle Secure Coding Standard for Java"
  * By Dhruv Mohindra, Robert C. Seacord p.378
- * <p>
+ * <p/>
  * Singleton objects usually are heavy to create and sometimes need to serialize them.
  * This class also shows how to preserve singleton in serialized version of singleton.
  *
  * @author mortezaadi@gmail.com
- *
  */
-public class InitializingOnDemandHolderIdiom implements Serializable{
+public class InitializingOnDemandHolderIdiom implements Serializable {
 
-	private static final long serialVersionUID = 1L;
+    private static final long serialVersionUID = 1L;
 
-	private static class HelperHolder {
+    private InitializingOnDemandHolderIdiom() {
-		public static final InitializingOnDemandHolderIdiom INSTANCE = new InitializingOnDemandHolderIdiom();
+    }
-	}
 
-	public static InitializingOnDemandHolderIdiom getInstance() {
+    public static InitializingOnDemandHolderIdiom getInstance() {
-		return HelperHolder.INSTANCE;
+        return HelperHolder.INSTANCE;
-	}
+    }
 
-	private InitializingOnDemandHolderIdiom() {
+    protected Object readResolve() {
-	}
+        return getInstance();
+    }
 
-	protected Object readResolve() {
+    private static class HelperHolder {
-		return getInstance();
+        public static final InitializingOnDemandHolderIdiom INSTANCE = new InitializingOnDemandHolderIdiom();
-	}
+    }
 
 }

singleton/src/main/java/com/iluwatar/singleton/IvoryTower.java

@@ -1,20 +1,33 @@
+/**
+ * Singleton pattern.
+ */
 package com.iluwatar.singleton;
 
 /**
- * 
  * Singleton class.
  * Eagerly initialized static instance guarantees thread
  * safety.
- * 
  */
-public class IvoryTower {
+public final class IvoryTower {
 
-	private static IvoryTower instance = new IvoryTower();
+    /**
+     * Static to class instance of the class.
+     */
+    private static IvoryTower instance = new IvoryTower();
 
-	private IvoryTower() {
+    /**
-	}
+     * Private constructor so nobody can instantiate the class.
+     */
+    private IvoryTower() {
+    }
 
-	public static IvoryTower getInstance() {
+    /**
-		return instance;
+     * To be called by user to
-	}
+     * obtain instance of the class.
+     *
+     * @return instance of the singleton.
+     */
+    public static IvoryTower getInstance() {
+        return instance;
+    }
 }

singleton/src/main/java/com/iluwatar/singleton/ThreadSafeDoubleCheckLocking.java

@@ -1,41 +1,43 @@
+/**
+ * Singleton pattern.
+ *
+ */
 package com.iluwatar.singleton;
 
 /**
  * Double check locking
- * <p>
+ * <p/>
  * http://www.cs.umd.edu/~pugh/java/memoryModel/DoubleCheckedLocking.html
- * <p>
+ * <p/>
  * Broken under Java 1.4.
  *
  * @author mortezaadi@gmail.com
- *
  */
 public class ThreadSafeDoubleCheckLocking {
 
-	private static volatile ThreadSafeDoubleCheckLocking INSTANCE;
+    private static volatile ThreadSafeDoubleCheckLocking INSTANCE;
 
-	/**
+    /**
-	 * private constructor to prevent client from instantiating.
+     * private constructor to prevent client from instantiating.
-	 * 
+     */
-	 */
+    private ThreadSafeDoubleCheckLocking() {
-	private ThreadSafeDoubleCheckLocking() {
+        //to prevent instantiating by Reflection call
-		//to prevent instantiating by Reflection call 
+        if (INSTANCE != null)
-		if(INSTANCE != null)
+            throw new IllegalStateException("Already initialized.");
-			throw new IllegalStateException("Already initialized.");
+    }
-	}
 
-	public static ThreadSafeDoubleCheckLocking getInstance() {
+    public static ThreadSafeDoubleCheckLocking getInstance() {
-		//local variable increases performance by 25 percent 
+        //local variable increases performance by 25 percent
-		//Joshua Bloch "Effective Java, Second Edition", p. 283-284
+        //Joshua Bloch "Effective Java, Second Edition", p. 283-284
-		ThreadSafeDoubleCheckLocking result = INSTANCE;
+        ThreadSafeDoubleCheckLocking result = INSTANCE;
-		if (result == null) {
+        if (result == null) {
-			synchronized (ThreadSafeDoubleCheckLocking.class) {
+            synchronized (ThreadSafeDoubleCheckLocking.class) {
-				result = INSTANCE;
+                result = INSTANCE;
-				if (result == null) {
+                if (result == null) {
-					INSTANCE = result = new ThreadSafeDoubleCheckLocking();
+                    INSTANCE = result = new ThreadSafeDoubleCheckLocking();
-				}
+                }
-			}
+            }
-		}
+        }
-		return result;
+        return result;
-	}
+    }
 }

singleton/src/main/java/com/iluwatar/singleton/ThreadSafeLazyLoadedIvoryTower.java

@@ -1,28 +1,29 @@
+/**
+ * Singleton pattern.
+ */
 package com.iluwatar.singleton;
 
 /**
- *
  * Thread-safe Singleton class.
  * The instance is lazily initialized and thus needs synchronization
  * mechanism.
- *
  */
 public class ThreadSafeLazyLoadedIvoryTower {
 
-	private static ThreadSafeLazyLoadedIvoryTower instance = null;
+    private static ThreadSafeLazyLoadedIvoryTower instance = null;
 
-	private ThreadSafeLazyLoadedIvoryTower() {
+    private ThreadSafeLazyLoadedIvoryTower() {
-	}
+    }
 
-	public synchronized static ThreadSafeLazyLoadedIvoryTower getInstance() {
+    public synchronized static ThreadSafeLazyLoadedIvoryTower getInstance() {
-		/*
+        /*
-		 * The instance gets created only when it is called for first time.
+         * The instance gets created only when it is called for first time.
-		 * Lazy-loading
+         * Lazy-loading
-		 */
+         */
-		if (instance == null) {
+        if (instance == null) {
-			instance = new ThreadSafeLazyLoadedIvoryTower();
+            instance = new ThreadSafeLazyLoadedIvoryTower();
-		}
+        }
 
-		return instance;
+        return instance;
-	}
+    }
 }