diff --git a/singleton/src/main/java/com/iluwatar/singleton/App.java b/singleton/src/main/java/com/iluwatar/singleton/App.java
index e8a3a1571..11cb4daa6 100644
--- a/singleton/src/main/java/com/iluwatar/singleton/App.java
+++ b/singleton/src/main/java/com/iluwatar/singleton/App.java
@@ -1,58 +1,63 @@
 /**
  * Singleton pattern.
  */
+
 package com.iluwatar.singleton;
 
 /**
- *
  * Singleton pattern ensures that the class ({@link IvoryTower}) can have only one
- * existing instance per Java classloader instance and provides global access to it. 
- * <p>
+ * existing instance per Java classloader instance and provides global access to it.
+ * <p/>
  * http://stackoverflow.com/questions/70689/what-is-an-efficient-way-to-implement-a-singleton-pattern-in-java
- *<p>
- * The risk of this pattern is that bugs resulting from setting a singleton up in a distributed environment can 
- * be tricky to debug, since it will work fine if you debug with a single classloader. Additionally, these
- * problems can crop up a while after the implementation of a singleton, since they may start out synchronous and
- * only become async with time, so you it may not be clear why you are seeing certain changes in behaviour.
- * <p>
+ * <p/>
+ * The risk of this pattern is that bugs resulting from setting a singleton up in
+ * a distributed environment can be tricky to debug, since it will work fine if you
+ * debug with a single classloader. Additionally, these problems can crop up a while
+ * after the implementation of a singleton, since they may start out synchronous and
+ * only become async with time, so you it may not be clear why you are seeing certain
+ * changes in behaviour.
+ * <p/>
  * http://stackoverflow.com/questions/17721263/singleton-across-jvm-or-application-instance-or-tomcat-instance
  */
 public class App {
 
-    /**
-     * Program entry point
-     * @param args command line args
-     */
-    public static void main(String[] args) {
+  /**
+   * Program entry point.
+   *
+   * @param args command line args
+   */
+  public static void main(String[] args) {
 
-        // eagerly initialized singleton
-        IvoryTower ivoryTower1 = IvoryTower.getInstance();
-        IvoryTower ivoryTower2 = IvoryTower.getInstance();
-        System.out.println("ivoryTower1=" + ivoryTower1);
-        System.out.println("ivoryTower2=" + ivoryTower2);
+    // eagerly initialized singleton
+    IvoryTower ivoryTower1 = IvoryTower.getInstance();
+    IvoryTower ivoryTower2 = IvoryTower.getInstance();
+    System.out.println("ivoryTower1=" + ivoryTower1);
+    System.out.println("ivoryTower2=" + ivoryTower2);
 
-        // lazily initialized singleton
-        ThreadSafeLazyLoadedIvoryTower threadSafeIvoryTower1 = ThreadSafeLazyLoadedIvoryTower
-                .getInstance();
-        ThreadSafeLazyLoadedIvoryTower threadSafeIvoryTower2 = ThreadSafeLazyLoadedIvoryTower
-                .getInstance();
-        System.out.println("threadSafeIvoryTower1=" + threadSafeIvoryTower1);
-        System.out.println("threadSafeIvoryTower2=" + threadSafeIvoryTower2);
+    // lazily initialized singleton
+    ThreadSafeLazyLoadedIvoryTower threadSafeIvoryTower1 = ThreadSafeLazyLoadedIvoryTower
+            .getInstance();
+    ThreadSafeLazyLoadedIvoryTower threadSafeIvoryTower2 = ThreadSafeLazyLoadedIvoryTower
+            .getInstance();
+    System.out.println("threadSafeIvoryTower1=" + threadSafeIvoryTower1);
+    System.out.println("threadSafeIvoryTower2=" + threadSafeIvoryTower2);
 
-        // enum singleton
-        EnumIvoryTower enumIvoryTower1 = EnumIvoryTower.INSTANCE;
-        EnumIvoryTower enumIvoryTower2 = EnumIvoryTower.INSTANCE;
-        System.out.println("enumIvoryTower1=" + enumIvoryTower1);
-        System.out.println("enumIvoryTower2=" + enumIvoryTower2);
+    // enum singleton
+    EnumIvoryTower enumIvoryTower1 = EnumIvoryTower.INSTANCE;
+    EnumIvoryTower enumIvoryTower2 = EnumIvoryTower.INSTANCE;
+    System.out.println("enumIvoryTower1=" + enumIvoryTower1);
+    System.out.println("enumIvoryTower2=" + enumIvoryTower2);
 
-        InitializingOnDemandHolderIdiom demandHolderIdiom = InitializingOnDemandHolderIdiom.getInstance();
-        System.out.println(demandHolderIdiom);
-        InitializingOnDemandHolderIdiom demandHolderIdiom2 = InitializingOnDemandHolderIdiom.getInstance();
-        System.out.println(demandHolderIdiom2);
+    InitializingOnDemandHolderIdiom demandHolderIdiom =
+            InitializingOnDemandHolderIdiom.getInstance();
+    System.out.println(demandHolderIdiom);
+    InitializingOnDemandHolderIdiom demandHolderIdiom2 =
+            InitializingOnDemandHolderIdiom.getInstance();
+    System.out.println(demandHolderIdiom2);
 
-        ThreadSafeDoubleCheckLocking dcl1 = ThreadSafeDoubleCheckLocking.getInstance();
-        System.out.println(dcl1);
-        ThreadSafeDoubleCheckLocking dcl2 = ThreadSafeDoubleCheckLocking.getInstance();
-        System.out.println(dcl2);
-    }
+    ThreadSafeDoubleCheckLocking dcl1 = ThreadSafeDoubleCheckLocking.getInstance();
+    System.out.println(dcl1);
+    ThreadSafeDoubleCheckLocking dcl2 = ThreadSafeDoubleCheckLocking.getInstance();
+    System.out.println(dcl2);
+  }
 }
diff --git a/singleton/src/main/java/com/iluwatar/singleton/EnumIvoryTower.java b/singleton/src/main/java/com/iluwatar/singleton/EnumIvoryTower.java
index b2523a45f..f39babe45 100644
--- a/singleton/src/main/java/com/iluwatar/singleton/EnumIvoryTower.java
+++ b/singleton/src/main/java/com/iluwatar/singleton/EnumIvoryTower.java
@@ -1,18 +1,15 @@
-/**
- * Enum Singleton class.
- * Effective Java 2nd Edition (Joshua Bloch) p. 18
- */
 package com.iluwatar.singleton;
 
 /**
  * Enum based singleton implementation.
+ * Effective Java 2nd Edition (Joshua Bloch) p. 18
  */
 public enum EnumIvoryTower {
 
-    INSTANCE;
+  INSTANCE;
 
-    @Override
-    public String toString() {
-        return getDeclaringClass().getCanonicalName() + "@" + hashCode();
-    }
+  @Override
+  public String toString() {
+    return getDeclaringClass().getCanonicalName() + "@" + hashCode();
+  }
 }
diff --git a/singleton/src/main/java/com/iluwatar/singleton/InitializingOnDemandHolderIdiom.java b/singleton/src/main/java/com/iluwatar/singleton/InitializingOnDemandHolderIdiom.java
index 423bc3242..88738b8ca 100644
--- a/singleton/src/main/java/com/iluwatar/singleton/InitializingOnDemandHolderIdiom.java
+++ b/singleton/src/main/java/com/iluwatar/singleton/InitializingOnDemandHolderIdiom.java
@@ -1,6 +1,3 @@
-/**
- * Singleton pattern.
- */
 package com.iluwatar.singleton;
 
 import java.io.Serializable;
@@ -18,21 +15,22 @@ import java.io.Serializable;
  */
 public class InitializingOnDemandHolderIdiom implements Serializable {
 
-    private static final long serialVersionUID = 1L;
+  private static final long serialVersionUID = 1L;
 
-    private InitializingOnDemandHolderIdiom() {
-    }
+  private InitializingOnDemandHolderIdiom() {
+  }
 
-    public static InitializingOnDemandHolderIdiom getInstance() {
-        return HelperHolder.INSTANCE;
-    }
+  public static InitializingOnDemandHolderIdiom getInstance() {
+    return HelperHolder.INSTANCE;
+  }
 
-    protected Object readResolve() {
-        return getInstance();
-    }
+  protected Object readResolve() {
+    return getInstance();
+  }
 
-    private static class HelperHolder {
-        public static final InitializingOnDemandHolderIdiom INSTANCE = new InitializingOnDemandHolderIdiom();
-    }
+  private static class HelperHolder {
+    public static final InitializingOnDemandHolderIdiom INSTANCE =
+            new InitializingOnDemandHolderIdiom();
+  }
 
 }
diff --git a/singleton/src/main/java/com/iluwatar/singleton/IvoryTower.java b/singleton/src/main/java/com/iluwatar/singleton/IvoryTower.java
index 29f9e1b24..96809c477 100644
--- a/singleton/src/main/java/com/iluwatar/singleton/IvoryTower.java
+++ b/singleton/src/main/java/com/iluwatar/singleton/IvoryTower.java
@@ -1,6 +1,3 @@
-/**
- * Singleton pattern.
- */
 package com.iluwatar.singleton;
 
 /**
@@ -10,24 +7,24 @@ package com.iluwatar.singleton;
  */
 public final class IvoryTower {
 
-    /**
-     * Static to class instance of the class.
-     */
-    private static IvoryTower instance = new IvoryTower();
+  /**
+   * Static to class instance of the class.
+   */
+  private static IvoryTower instance = new IvoryTower();
 
-    /**
-     * Private constructor so nobody can instantiate the class.
-     */
-    private IvoryTower() {
-    }
+  /**
+   * Private constructor so nobody can instantiate the class.
+   */
+  private IvoryTower() {
+  }
 
-    /**
-     * To be called by user to
-     * obtain instance of the class.
-     *
-     * @return instance of the singleton.
-     */
-    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;
+  }
 }
diff --git a/singleton/src/main/java/com/iluwatar/singleton/ThreadSafeDoubleCheckLocking.java b/singleton/src/main/java/com/iluwatar/singleton/ThreadSafeDoubleCheckLocking.java
index c0ac0b4c4..26b57d4cf 100644
--- a/singleton/src/main/java/com/iluwatar/singleton/ThreadSafeDoubleCheckLocking.java
+++ b/singleton/src/main/java/com/iluwatar/singleton/ThreadSafeDoubleCheckLocking.java
@@ -1,7 +1,3 @@
-/**
- * Singleton pattern.
- *
- */
 package com.iluwatar.singleton;
 
 /**
@@ -15,29 +11,35 @@ package com.iluwatar.singleton;
  */
 public class ThreadSafeDoubleCheckLocking {
 
-    private static volatile ThreadSafeDoubleCheckLocking INSTANCE;
+  private static volatile ThreadSafeDoubleCheckLocking INSTANCE;
 
-    /**
-     * private constructor to prevent client from instantiating.
-     */
-    private ThreadSafeDoubleCheckLocking() {
-        //to prevent instantiating by Reflection call
-        if (INSTANCE != null)
-            throw new IllegalStateException("Already initialized.");
+  /**
+   * private constructor to prevent client from instantiating.
+   */
+  private ThreadSafeDoubleCheckLocking() {
+    //to prevent instantiating by Reflection call
+    if (INSTANCE != null) {
+      throw new IllegalStateException("Already initialized.");
     }
+  }
 
-    public static ThreadSafeDoubleCheckLocking getInstance() {
-        //local variable increases performance by 25 percent
-        //Joshua Bloch "Effective Java, Second Edition", p. 283-284
-        ThreadSafeDoubleCheckLocking result = INSTANCE;
+  /**
+   * Public accessor.
+   *
+   * @return an instance of the class.
+   */
+  public static ThreadSafeDoubleCheckLocking getInstance() {
+    //local variable increases performance by 25 percent
+    //Joshua Bloch "Effective Java, Second Edition", p. 283-284
+    ThreadSafeDoubleCheckLocking result = INSTANCE;
+    if (result == null) {
+      synchronized (ThreadSafeDoubleCheckLocking.class) {
+        result = INSTANCE;
         if (result == null) {
-            synchronized (ThreadSafeDoubleCheckLocking.class) {
-                result = INSTANCE;
-                if (result == null) {
-                    INSTANCE = result = new ThreadSafeDoubleCheckLocking();
-                }
-            }
+          INSTANCE = result = new ThreadSafeDoubleCheckLocking();
         }
-        return result;
+      }
     }
+    return result;
+  }
 }
diff --git a/singleton/src/main/java/com/iluwatar/singleton/ThreadSafeLazyLoadedIvoryTower.java b/singleton/src/main/java/com/iluwatar/singleton/ThreadSafeLazyLoadedIvoryTower.java
index b1f9b81a3..f9b62e798 100644
--- a/singleton/src/main/java/com/iluwatar/singleton/ThreadSafeLazyLoadedIvoryTower.java
+++ b/singleton/src/main/java/com/iluwatar/singleton/ThreadSafeLazyLoadedIvoryTower.java
@@ -1,6 +1,3 @@
-/**
- * Singleton pattern.
- */
 package com.iluwatar.singleton;
 
 /**
@@ -10,20 +7,21 @@ package com.iluwatar.singleton;
  */
 public class ThreadSafeLazyLoadedIvoryTower {
 
-    private static ThreadSafeLazyLoadedIvoryTower instance = null;
+  private static ThreadSafeLazyLoadedIvoryTower instance = null;
 
-    private ThreadSafeLazyLoadedIvoryTower() {
+  private ThreadSafeLazyLoadedIvoryTower() {
+  }
+
+  /**
+   * The instance gets created only when it is called for first time.
+   * Lazy-loading
+   */
+  public synchronized static ThreadSafeLazyLoadedIvoryTower getInstance() {
+
+    if (instance == null) {
+      instance = new ThreadSafeLazyLoadedIvoryTower();
     }
 
-    public synchronized static ThreadSafeLazyLoadedIvoryTower getInstance() {
-        /*
-         * The instance gets created only when it is called for first time.
-         * Lazy-loading
-         */
-        if (instance == null) {
-            instance = new ThreadSafeLazyLoadedIvoryTower();
-        }
-
-        return instance;
-    }
+    return instance;
+  }
 }