com.google.common.util.concurrent

Class Futures.FutureCombiner<V>

java.lang.Object

com.google.common.util.concurrent.Futures.FutureCombiner<V>

Enclosing class:

Futures

@Beta
 @CanIgnoreReturnValue
 @GwtCompatible
public static final class Futures.FutureCombiner<V>
extends Object

A helper to create a new ListenableFuture whose result is generated from a combination of input futures.

See Futures.whenAllComplete(com.google.common.util.concurrent.ListenableFuture<? extends V>...) and Futures.whenAllSucceed(com.google.common.util.concurrent.ListenableFuture<? extends V>...) for how to instantiate this class.

Example:

 final ListenableFuture<Instant> loginDateFuture =
     loginService.findLastLoginDate(username);
 final ListenableFuture<List<String>> recentCommandsFuture =
     recentCommandsService.findRecentCommands(username);
 Callable<UsageHistory> usageComputation =
     new Callable<UsageHistory>() {
       public UsageHistory call() throws Exception {
         return new UsageHistory(
             username, loginDateFuture.get(), recentCommandsFuture.get());
       }
     };
 ListenableFuture<UsageHistory> usageFuture =
     Futures.whenAllSucceed(loginDateFuture, recentCommandsFuture)
         .call(usageComputation, executor);
 

Since:

20.0

Method Summary

Modifier and Type	Method and Description
<C> ListenableFuture<C>	call(Callable<C> combiner, Executor executor) Creates the ListenableFuture which will return the result of calling Callable.call() in combiner when all futures complete, using the specified executor.
<C> ListenableFuture<C>	callAsync(AsyncCallable<C> combiner, Executor executor) Creates the ListenableFuture which will return the result of calling AsyncCallable.call() in combiner when all futures complete, using the specified executor.
ListenableFuture<?>	run(Runnable combiner, Executor executor) Creates the ListenableFuture which will return the result of running combiner when all Futures complete.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

callAsync

public <C> ListenableFuture<C> callAsync(AsyncCallable<C> combiner,
                                         Executor executor)

Creates the ListenableFuture which will return the result of calling AsyncCallable.call() in combiner when all futures complete, using the specified executor.

If the combiner throws a CancellationException, the returned future will be cancelled.

If the combiner throws an ExecutionException, the cause of the thrown ExecutionException will be extracted and returned as the cause of the new ExecutionException that gets thrown by the returned combined future.

Canceling this future will attempt to cancel all the component futures.

call

@CanIgnoreReturnValue
public <C> ListenableFuture<C> call(Callable<C> combiner,
                                                          Executor executor)

Creates the ListenableFuture which will return the result of calling Callable.call() in combiner when all futures complete, using the specified executor.

If the combiner throws a CancellationException, the returned future will be cancelled.

If the combiner throws an ExecutionException, the cause of the thrown ExecutionException will be extracted and returned as the cause of the new ExecutionException that gets thrown by the returned combined future.

Canceling this future will attempt to cancel all the component futures.

run

public ListenableFuture<?> run(Runnable combiner,
                               Executor executor)

Creates the ListenableFuture which will return the result of running combiner when all Futures complete. combiner will run using executor.

If the combiner throws a CancellationException, the returned future will be cancelled.

Canceling this Future will attempt to cancel all the component futures.

Since:

23.6