Java in a Nutshell, 5th Edition [Electronic resources] نسخه متنی

This
class holds a thread-local value that is inherited by child threads.
See ThreadLocal for a discussion of thread-local
values. Note that the inheritance referred to in the name of this
class is not from superclass to subclass; it is inheritance from
parent thread to child thread. Like its superclass, this class has
been made generic in Java 5.0. The type variable
T represents the type of the referenced
object.

This class is best understood by example. Suppose that an application
has defined an InheritableThreadLocal object and
that a certain thread (the parent thread) has a thread-local value
stored in that object. Whenever that thread creates a new thread (a
child thread), the InheritableThreadLocal object
is automatically updated so that the new child thread has the same
value associated with it as the parent thread. Note that the value
associated with the child thread is independent from the value
associated with the parent thread. If the child thread subsequently
alters its value by calling the set( ) method of
the InheritableThreadLocal, the value associated
with the parent thread does not change.

By default, a child thread inherits a parent's
values unmodified. By overriding the childValue( )
method, however, you can create a subclass of
InheritableThreadLocal in which the child thread
inherits some arbitrary function of the parent
thread's value.

Figure 10-32. java.lang.InheritableThreadLocal<T>

public class

InheritableThreadLocal<T> extends ThreadLocal<T> {
// Public Constructors
public

InheritableThreadLocal ( );
// Protected Instance Methods
protected T

childValue (T

parentValue );
}