@Beta @GwtCompatible public interface CheckedFuture<V,X extends Exception> extends ListenableFuture<V>
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()
.
Modifier and Type | Method and Description |
---|---|
V |
checkedGet()
Exception checking version of
Future.get() that will translate
InterruptedException , CancellationException and
ExecutionException into application-specific exceptions. |
V |
checkedGet(long timeout,
TimeUnit unit)
Exception checking version of
Future.get(long, TimeUnit) that will
translate InterruptedException , CancellationException and
ExecutionException into application-specific exceptions. |
addListener
V checkedGet() throws X extends Exception
Future.get()
that will translate
InterruptedException
, CancellationException
and
ExecutionException
into application-specific exceptions.V checkedGet(long timeout, TimeUnit unit) throws TimeoutException, X extends Exception
Future.get(long, TimeUnit)
that will
translate InterruptedException
, CancellationException
and
ExecutionException
into application-specific exceptions. On
timeout this method throws a normal TimeoutException
.TimeoutException
- if retrieving the result timed out.X
- on interruption, cancellation or execution exceptions.X extends Exception
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