/*
 * The MIT License
 * Copyright © 2014-2019 Ilkka Seppälä
 *
 * 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:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * 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.
 */

package com.iluwatar.singleton;

/**
 * <p>Thread-safe Singleton class. The instance is lazily initialized and thus needs synchronization
 * mechanism.</p>
 *
 * <p>Note: if created by reflection then a singleton will not be created but multiple options
 * in the same classloader</p>
 */
public final class ThreadSafeLazyLoadedIvoryTower {

  private static ThreadSafeLazyLoadedIvoryTower instance;

  private ThreadSafeLazyLoadedIvoryTower() {
    // protect against instantiation via reflection
    if (instance == null) {
      instance = this;
    } else {
      throw new IllegalStateException("Already initialized.");
    }
  }

  /**
   * The instance gets created only when it is called for first time. Lazy-loading
   */
  public static synchronized ThreadSafeLazyLoadedIvoryTower getInstance() {
    if (instance == null) {
      instance = new ThreadSafeLazyLoadedIvoryTower();
    }

    return instance;
  }
}

@@ -1297,134 +1297,8 @@
 %0A *%0A
- * %3Cp%3ENote: if created by reflection then a singleton will not be created but multiple options%0A * in the same classloader%3C/p%3E%0A
  */%0A
@@ -1367,16 +1367,25 @@
  static 
+volatile 
 ThreadSa
@@ -1470,17 +1470,17 @@
 %0A    // 
-p
+P
 rotect a
@@ -1681,12 +1681,19 @@
 nce 
+doesn't 
 get
-s
  cre
@@ -1701,20 +1701,24 @@
 ted 
-only when it
+until the method
  is 
@@ -1728,16 +1728,20 @@
 led for 
+the 
 first ti
@@ -1746,22 +1746,8 @@
 time
-. Lazy-loading
 %0A   
@@ -1845,32 +1845,128 @@
 ance == null) %7B%0A
+      synchronized (ThreadSafeLazyLoadedIvoryTower.class) %7B%0A        if (instance == null) %7B%0A    
       instance =
@@ -2008,18 +2008,35 @@
 ();%0A    
+    %7D%0A      %7D%0A    
 %7D
-%0A
 %0A    ret

Improve lazy loaded Singleton example