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Class java.lang.ThreadLocal
java.lang.Object
|
+----java.lang.ThreadLocal
- public class ThreadLocal
- extends Object
This class provides ThreadLocal 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 objects are typically private static variables in
classes that wish to associate state with a thread (e.g., a user ID or
Transaction ID).
Each thread holds an implicit.reference to its copy of a ThreadLocal
as long as the thread is alive and the ThreadLocal object is accessible;
after a thread goes away, all of its copies of ThreadLocal variables are
subject to garbage collection (unless other references to these copies
exist).
ThreadLocal()
- Creates a ThreadLocal variable.
get()
- Returns the calling thread's instance of this ThreadLocal variable.
initialize()
- Returns the calling thread's initial value for this ThreadLocal
variable.
set(Object)
- Sets the calling thread's instance of this ThreadLocal variable
to the given value.
ThreadLocal
public ThreadLocal()
- Creates a ThreadLocal variable.
initialize
protected Object initialize()
- Returns the calling thread's initial value for this ThreadLocal
variable. This method will be called once per accessing thread for
each ThreadLocal, the first time each thread accesses the variable
with get or set. If the programmer desires ThreadLocal variables
to be initialized to some value other than null, ThreadLocal must
be subclassed, and this method overridden. Typically, an anonymous
inner class will be used. Typical implementations of initialize
will call an appropriate constructor and return the newly constructed
object.
get
public Object get()
- Returns the calling thread's instance of this ThreadLocal variable.
Initializes the instance if this is the first time the thread
has called this method.
set
public void set(Object value)
- Sets the calling thread's instance of this ThreadLocal variable
to the given value. This is only used to change the value from
the one assigned by the initialize method, and most applications
will have no need for this functionality.
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