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Merge pull request #609 from igorcadelima/master

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Protect against instantiation via reflection
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Ilkka Seppälä 2018-02-17 20:36:40 +02:00 committed by GitHub
commit f9f93695fe
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1 changed files with 16 additions and 19 deletions
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35
singleton/src/main/java/com/iluwatar/singleton/ThreadSafeLazyLoadedIvoryTower.java
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@ -1,24 +1,20 @@
/** /**
* The MIT License * The MIT License Copyright (c) 2014-2016 Ilkka Seppälä
* Copyright (c) 2014-2016 Ilkka Seppälä
* *
* Permission is hereby granted, free of charge, to any person obtaining a copy * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
* of this software and associated documentation files (the "Software"), to deal * associated documentation files (the "Software"), to deal in the Software without restriction,
* in the Software without restriction, including without limitation the rights * including without limitation the rights to use, copy, modify, merge, publish, distribute,
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions: * furnished to do so, subject to the following conditions:
* *
* The above copyright notice and this permission notice shall be included in * The above copyright notice and this permission notice shall be included in all copies or
* all copies or substantial portions of the Software. * substantial portions of the Software.
* *
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* 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.
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/ */
package com.iluwatar.singleton; package com.iluwatar.singleton;
@ -34,8 +30,10 @@ public final class ThreadSafeLazyLoadedIvoryTower {
private static ThreadSafeLazyLoadedIvoryTower instance; private static ThreadSafeLazyLoadedIvoryTower instance;
private ThreadSafeLazyLoadedIvoryTower() { private ThreadSafeLazyLoadedIvoryTower() {
// to prevent instantiating by Reflection call // protect against instantiation via reflection
if (instance != null) { if (instance == null) {
instance = this;
} else {
throw new IllegalStateException("Already initialized."); throw new IllegalStateException("Already initialized.");
} }
} }
@ -44,7 +42,6 @@ public final class ThreadSafeLazyLoadedIvoryTower {
* The instance gets created only when it is called for first time. Lazy-loading * The instance gets created only when it is called for first time. Lazy-loading
*/ */
public static synchronized ThreadSafeLazyLoadedIvoryTower getInstance() { public static synchronized ThreadSafeLazyLoadedIvoryTower getInstance() {
if (instance == null) { if (instance == null) {
instance = new ThreadSafeLazyLoadedIvoryTower(); instance = new ThreadSafeLazyLoadedIvoryTower();
} }