Package com.google.common.util.concurrent

Interface CheckedFuture<V,X extends java.lang.Exception>

All Superinterfaces:

java.util.concurrent.Future<V>, ListenableFuture<V>

All Known Implementing Classes:

AbstractCheckedFuture, ForwardingCheckedFuture, ForwardingCheckedFuture.SimpleForwardingCheckedFuture

@Beta
@GwtCompatible
public interface CheckedFuture<V,X extends java.lang.Exception>
extends ListenableFuture<V>

A CheckedFuture is a ListenableFuture that includes versions of the get methods that can throw a checked exception. This makes it easier to create a future that executes logic which can throw an exception.

Warning: We recommend against using CheckedFuture in new projects. CheckedFuture is difficult to build libraries atop. CheckedFuture ports of methods like Futures.transformAsync(com.google.common.util.concurrent.ListenableFuture<I>, com.google.common.util.concurrent.AsyncFunction<? super I, ? extends O>) have historically had bugs, and some of these bugs are necessary, unavoidable consequences of the CheckedFuture API. Additionally, CheckedFuture encourages users to take exceptions from one thread and rethrow them in another, producing confusing stack traces.

A common implementation is Futures.immediateCheckedFuture(V).

Implementations of this interface must adapt the exceptions thrown by Future#get(): CancellationException, ExecutionException and InterruptedException into the type specified by the X type parameter.

This interface also extends the ListenableFuture interface to allow listeners to be added. This allows the future to be used as a normal Future or as an asynchronous callback mechanism as needed. This allows multiple callbacks to be registered for a particular task, and the future will guarantee execution of all listeners when the task completes.

For a simpler alternative to CheckedFuture, consider accessing Future values with Futures.getChecked().

Since:

1.0

Method Summary

Modifier and Type	Method	Description
V	checkedGet()	Exception checking version of Future.get() that will translate InterruptedException, CancellationException and ExecutionException into application-specific exceptions.
V	checkedGet(long timeout, java.util.concurrent.TimeUnit unit)	Exception checking version of Future.get(long, TimeUnit) that will translate InterruptedException, CancellationException and ExecutionException into application-specific exceptions.

Methods inherited from interface java.util.concurrent.Future

cancel, get, get, isCancelled, isDone

Methods inherited from interface com.google.common.util.concurrent.ListenableFuture

addListener

Method Detail

checkedGet

V checkedGet()
      throws X extends java.lang.Exception

Exception checking version of Future.get() that will translate InterruptedException, CancellationException and ExecutionException into application-specific exceptions.

Returns:

the result of executing the future.

Throws:

X - on interruption, cancellation or execution exceptions.

X extends java.lang.Exception

checkedGet

V checkedGet(long timeout,
             java.util.concurrent.TimeUnit unit)
      throws java.util.concurrent.TimeoutException,
             X extends java.lang.Exception

Exception checking version of Future.get(long, TimeUnit) that will translate InterruptedException, CancellationException and ExecutionException into application-specific exceptions. On timeout this method throws a normal TimeoutException.

Returns:

the result of executing the future.

Throws:

java.util.concurrent.TimeoutException - if retrieving the result timed out.

X - on interruption, cancellation or execution exceptions.

X extends java.lang.Exception