public class java.util.concurrent
FutureTask<V>


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Java SE 6
  
Implements: RunnableFuture
Details
A cancellable asynchronous computation. This class provides a base implementation of Future, 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; the get method will block if the computation has not yet completed. Once the computation has completed, the computation cannot be restarted or cancelled.

A FutureTask can be used to wrap a Callable or java.lang.Runnable object. Because FutureTask implements Runnable, a FutureTask can be submitted to an Executor for execution.

In addition to serving as a standalone class, this class provides protected functionality that may be useful when creating customized task classes.
since1.5
VThe result type returned by this FutureTask's get method


Constructors
public FutureTask(Callable callable) Details
Creates a FutureTask that will upon running, execute the given Callable.
callablethe callable task
ThrowsNullPointerException: if callable is null
public FutureTask(Runnable runnable, Object result) Details
Creates a FutureTask that will upon running, execute the given Runnable, and arrange that get will return the given result on successful completion.
runnablethe runnable task
resultthe 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)
ThrowsNullPointerException: if runnable is null

Methods
public boolean cancel(boolean mayInterruptIfRunning)
protected void done()
Protected method invoked when this task transitions to state isDone (whether normally or via cancellation). The default implementation does nothing. Subclasses may override this method to invoke completion callbacks or perform bookkeeping. Note that you can query status inside the implementation of this method to determine whether this task has been cancelled.
public Object get() throws InterruptedException, ExecutionException Details
ThrowsCancellationException: if the computation was cancelled
public Object get(long timeout, TimeUnit unit) throws InterruptedException, ExecutionException, TimeoutException Details
ThrowsCancellationException: if the computation was cancelled
public void run()
Sets this Future to the result of its computation unless it has been cancelled.
protected boolean runAndReset() Details
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. This is designed for use with tasks that intrinsically execute more than once.
returntrue if successfully run and reset
protected void set(Object v) Details
Sets the result of this Future to the given value unless this future has already been set or has been cancelled. This method is invoked internally by the run method upon successful completion of the computation.
vthe value

Properties
public boolean isCancelled()
public boolean isDone()
protected void setException(Throwable t) Details
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. This method is invoked internally by the run method upon failure of the computation.
tthe cause of failure
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Java SE 6
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