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A thread-safe Java object reference that will only initialize its value when get() is called
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/* | |
Copyright (c) 2014 Stijn Van Bael | |
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. | |
*/ | |
import java.io.Serializable; | |
/** | |
* A thread-safe lazy object reference that will only initialize its value when get() is called. | |
*/ | |
public abstract class Lazy<T> implements Serializable { | |
private volatile T object; | |
private volatile boolean initialized; | |
public T get() { | |
T result = object; | |
if (!initialized) { | |
synchronized (this) { | |
result = object; | |
if (!initialized) { | |
object = result = initialize(); | |
initialized = true; | |
} | |
} | |
} | |
return result; | |
} | |
protected abstract T initialize(); | |
public synchronized boolean isInitialized() { | |
return initialized; | |
} | |
public synchronized void reset() { | |
initialized = false; | |
} | |
} |
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