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[LANG-496] Added a comment why a temporary variable is used in get(). 

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/lang/trunk@819146 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Oliver Heger 2009-09-26 15:03:06 +00:00
parent f4ae31ef19
commit 1e060c6e35
1 changed files with 16 additions and 7 deletions
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23
src/java/org/apache/commons/lang/concurrent/LazyInitializer.java
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@ -42,9 +42,11 @@ package org.apache.commons.lang.concurrent;
* to this class, a subclass of {@code LazyInitializer} has to be created:
*
* <pre>
* public class ComplexObjectInitializer extends LazyInitializer&lt;ComplexObject&gt; {
* public class ComplexObjectInitializer extends LazyInitializer&lt;ComplexObject&gt;
* {
* &#064;Override
* protected ComplexObject initialize() {
* protected ComplexObject initialize()
* {
* return new ComplexObject();
* }
* }
@ -75,7 +77,8 @@ package org.apache.commons.lang.concurrent;
* @version $Id$
* @param <T> the type of the object managed by this initializer class
*/
public abstract class LazyInitializer<T> {
public abstract class LazyInitializer<T>
{
/** Stores the managed object. */
private volatile T object;
@ -85,13 +88,19 @@ public abstract class LazyInitializer<T> {
*
* @return the object initialized by this {@code LazyInitializer}
*/
public T get() {
public T get()
{
// use a temporary variable to reduce the number of reads of the
// volatile field
T result = object;
if (result == null) {
synchronized (this) {
if (result == null)
{
synchronized (this)
{
result = object;
if (result == null) {
if (result == null)
{
object = result = initialize();
}
}