| java.lang.Object
 java.util.concurrent.FutureTask
| FutureTask | | public class FutureTask implements RunnableFuture<V>(Code) | | 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.
since:
1.5
author:
Doug Lea<
Parameters:
V - > The result type returned by this FutureTask's get method |
| Constructor Summary | |
| public | FutureTask(Callable<V> callable)
Creates a FutureTask that will, upon running, execute the
given Callable. | | public | 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.
Parameters:
runnable - the runnable task
Parameters:
result - the result to return on successful completion. |
| Method Summary | |
| public boolean | cancel(boolean mayInterruptIfRunning)
| | protected void | done()
Protected method invoked when this task transitions to state
isDone (whether normally or via cancellation). | | public V | get()
| | public V | get(long timeout, TimeUnit unit)
| | public boolean | isCancelled()
| | public boolean | isDone()
| | public void | run()
Sets this Future to the result of its computation
unless it has been cancelled. | | protected boolean | 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. | | protected void | set(V v)
Sets the result of this Future to the given value unless
this future has already been set or has been cancelled. | | protected void | 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. |
| FutureTask | | public FutureTask(Callable<V> callable)(Code) | | Creates a FutureTask that will, upon running, execute the
given Callable.
Parameters:
callable - the callable task
throws:
NullPointerException - if callable is null |
| FutureTask | | public FutureTask(Runnable runnable, V result)(Code) | | Creates a FutureTask that will, upon running, execute the
given Runnable, and arrange that get will return the
given result on successful completion.
Parameters:
runnable - the runnable task
Parameters:
result - the result to return on successful completion. Ifyou don't need a particular result, consider usingconstructions of the form:Future<?> f = new FutureTask<Object>(runnable, null)
throws:
NullPointerException - if runnable is null |
| cancel | | public boolean cancel(boolean mayInterruptIfRunning)(Code) | | |
| done | | protected void done()(Code) | | 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.
|
| isCancelled | | public boolean isCancelled()(Code) | | |
| isDone | | public boolean isDone()(Code) | | |
| run | | public void run()(Code) | | Sets this Future to the result of its computation
unless it has been cancelled.
|
| runAndReset | | protected boolean runAndReset()(Code) | | 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.
true if successfully run and reset |
| set | | protected void set(V v)(Code) | | 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.
Parameters:
v - the value |
| setException | | protected void setException(Throwable t)(Code) | | 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.
Parameters:
t - the cause of failure |
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