From 2ed3748c9bf0a6170cb07e647d7d758b4f6d6114 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ilkka=20Sepp=C3=A4l=C3=A4?= <ilkka.seppala@gofore.com>
Date: Sat, 7 May 2016 11:38:55 +0300
Subject: [PATCH] Improve Singleton holder example

---
 .../InitializingOnDemandHolderIdiom.java      | 37 ++++++++++---------
 1 file changed, 20 insertions(+), 17 deletions(-)

diff --git a/singleton/src/main/java/com/iluwatar/singleton/InitializingOnDemandHolderIdiom.java b/singleton/src/main/java/com/iluwatar/singleton/InitializingOnDemandHolderIdiom.java
index 84444ec2e..4aa6afe12 100644
--- a/singleton/src/main/java/com/iluwatar/singleton/InitializingOnDemandHolderIdiom.java
+++ b/singleton/src/main/java/com/iluwatar/singleton/InitializingOnDemandHolderIdiom.java
@@ -22,35 +22,38 @@
  */
 package com.iluwatar.singleton;
 
-import java.io.Serializable;
-
 /**
- * The Initialize-on-demand-holder idiom is a secure way of 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/>
- * 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.
+ * The Initialize-on-demand-holder idiom is a secure way of creating a lazy initialized singleton
+ * object in Java.
+ * <p>
+ * The technique is is as lazy as possible and works in all known versions of Java. It takes advantage
+ * of language guarantees about class initialization, and will therefore work correctly in all
+ * Java-compliant compilers and virtual machines.
+ * <p>
+ * The inner class is referenced no earlier (and therefore loaded no earlier by the class loader) than
+ * the moment that getInstance() is called. Thus, this solution is thread-safe without requiring special
+ * language constructs (i.e. volatile or synchronized).
  *
- * @author mortezaadi@gmail.com
  */
-public final class InitializingOnDemandHolderIdiom implements Serializable {
-
-  private static final long serialVersionUID = 1L;
+public final class InitializingOnDemandHolderIdiom {
 
+  /**
+   * Private constructor.
+   */
   private InitializingOnDemandHolderIdiom() {}
 
+  /**
+   * @return Singleton instance
+   */
   public static InitializingOnDemandHolderIdiom getInstance() {
     return HelperHolder.INSTANCE;
   }
 
-  protected Object readResolve() {
-    return getInstance();
-  }
-
+  /**
+   * Provides the lazy-loaded Singleton instance.
+   */
   private static class HelperHolder {
     public static final InitializingOnDemandHolderIdiom INSTANCE =
         new InitializingOnDemandHolderIdiom();
   }
-
 }