com.google.common.util.concurrent
Class ListenableFutureTask<V>

java.lang.Object
  java.util.concurrent.FutureTask<V>
      com.google.common.util.concurrent.ListenableFutureTask<V>

All Implemented Interfaces:

ListenableFuture<V>, Runnable, Future<V>, RunnableFuture<V>

@Beta
public class ListenableFutureTask<V>
extends FutureTask<V>
implements ListenableFuture<V>

A FutureTask that also implements the ListenableFuture interface. Subclasses must make sure to call super.done() if they also override the done() method, otherwise the listeners will not be called.

Since:

1

Author:

Sven Mawson

ListenableFutureTask

public ListenableFutureTask(Callable<V> callable)

Creates a ListenableFutureTask that will upon running, execute the given Callable.

Parameters:

callable - the callable task

Throws:

NullPointerException - if callable is null

ListenableFutureTask

public ListenableFutureTask(Runnable runnable,
                            V result)

Creates a ListenableFutureTask 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

result - the result to return on successful completion. If you don't need a particular result, consider using constructions of the form: ListenableFuture<?> f = new ListenableFutureTask<Object>(runnable, null)

Throws:

NullPointerException - if runnable is null

addListener

public void addListener(Runnable listener,
                        Executor exec)

Description copied from interface: ListenableFuture

Registers a listener to be run on the given executor. The listener will run when the Future's computation is complete or, if the computation is already complete, immediately.

There is no guaranteed ordering of execution of listeners, but any listener added through this method is guaranteed to be called once the computation is complete.

Listeners cannot throw checked exceptions and should not throw RuntimeException unless their executors are prepared to handle it. Listeners that will execute in MoreExecutors.sameThreadExecutor() should take special care, since they may run during the call to addListener or during the call that sets the future's value.

Specified by:

addListener in interface ListenableFuture<V>

Parameters:

listener - the listener to run when the computation is complete

exec - the executor to run the listener in

done

protected void done()

Description copied from class: java.util.concurrent.FutureTask

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.

Overrides:

done in class FutureTask<V>