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ThreadLocal owner = new ThreadLocal();
Based on 20 examples
public class ThreadLocal extends Object
This class provides thread-local variables. These variables differ from their normal counterparts in that each thread that accesses one (via its get or set method) has its own, independently initialized copy of the variable. ThreadLocal instances are typically private static fields in classes that wish to associate state with a thread (e.g., a user ID or Transaction ID).
For example, the class below generates unique identifiers local to each thread. A thread's id is assigned the first time it invokes UniqueThreadIdGenerator.getCurrentThreadId() and remains unchanged on subsequent calls.
import java.util.concurrent.atomic.AtomicInteger; public class UniqueThreadIdGenerator { private static final AtomicInteger uniqueId = new AtomicInteger(0); private static final ThreadLocal < Integer > uniqueNum = new ThreadLocal < Integer > () { @Override protected Integer initialValue() { return uniqueId.getAndIncrement(); } }; public static int getCurrentThreadId() { return uniqueId.get(); } } // UniqueThreadIdGenerator
Each thread holds an implicit reference to its copy of a thread-local variable as long as the thread is alive and the ThreadLocal instance is accessible; after a thread goes away, all of its copies of thread-local instances are subject to garbage collection (unless other references to these copies exist).
Constructor Summary | |
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Creates a thread local variable. |
Method Summary | |
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Object |
get() Returns the value in the current thread's copy of this thread-local variable. |
protected Object |
Returns the current thread's "initial value" for this thread-local variable. |
void |
remove() Removes the current thread's value for this thread-local variable. |
void |
Sets the current thread's copy of this thread-local variable to the specified value. |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public ThreadLocal()
Method Detail |
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public Object get()
protected Object initialValue()
This implementation simply returns null; if the programmer desires thread-local variables to have an initial value other than null, ThreadLocal must be subclassed, and this method overridden. Typically, an anonymous inner class will be used.
public void remove()
public void set(Object value)
value
- the value to be stored in the current thread's copy of
this thread-local.
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