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Java 2 Platform
Standard Ed. 5.0

Class FutureTask<V>

java.lang.Objectjava.util.concurrent.FutureTask<V>


Type Parameters:: V - The result type returned by this FutureTask'sget method

All Implemented Interfaces:: Runnable,Future<V>

public classFutureTask<V> extendsObject implementsFuture<V>,Runnable
extendsObject
implementsFuture<V>,Runnable

A cancellable asynchronous computation. This class provides a base implementation ofFuture, with methods to start and cancel a computation, query to see if the computation is complete, and retrieve the result of the computation. The result can only be retrieved when the computation has completed; theget method will block if the computation has not yet completed. Once the computation has completed, the computation cannot be restarted or cancelled.

AFutureTask can be used to wrap aCallable orRunnable object. BecauseFutureTask implementsRunnable, aFutureTask can be submitted to anExecutor for execution.

In addition to serving as a standalone class, this class providesprotected functionality that may be useful when creating customized task classes.

Since:: 1.5


`FutureTask(Callable<V> callable)` Creates a`FutureTask` that will upon running, execute the given`Callable`.
`FutureTask(Runnable runnable,V result)` Creates a`FutureTask` that will upon running, execute the given`Runnable`, and arrange that`get` will return the given result on successful completion.


	`cancel(boolean mayInterruptIfRunning)` Attempts to cancel execution of this task.
	`done()` Protected method invoked when this task transitions to state`isDone` (whether normally or via cancellation).
	`get()` Waits if necessary for the computation to complete, and then retrieves its result.
	`get(long timeout,TimeUnit unit)` Waits if necessary for at most the given time for the computation to complete, and then retrieves its result, if available.
	`isCancelled()` Returns`true` if this task was cancelled before it completed normally.
	`isDone()` Returns`true` if this task completed.
	`run()` Sets this Future to the result of computation unless it has been cancelled.
	`runAndReset()` Executes the computation without setting its result, and then resets this Future to initial state, failing to do so if the computation encounters an exception or is cancelled.
	`set(V v)` Sets the result of this Future to the given value unless this future has already been set or has been cancelled.
	`setException(Throwable t)` Causes this future to report an`ExecutionException` with the given throwable as its cause, unless this Future has already been set or has been cancelled.

Methods inherited from class java.lang.Object
`clone,equals,finalize,getClass,hashCode,notify,notifyAll,toString,wait,wait,wait`

FutureTask

publicFutureTask(Callable<V> callable)

Creates aFutureTask that will upon running, execute the givenCallable.

Parameters:: callable - the callable task
Throws:: NullPointerException - if callable is null

FutureTask

publicFutureTask(Runnable runnable,V result)

Creates aFutureTask that will upon running, execute the givenRunnable, and arrange thatget will return the given result on successful completion.

Parameters:: runnable - the runnable task; result - the result to return on successful completion. If you don't need a particular result, consider using constructions of the form:Future<?> f = new FutureTask<Object>(runnable, null)
Throws:: NullPointerException - if runnable is null