Package com.google.appengine.api.datastore

Class FutureHelper

java.lang.Object

com.google.appengine.api.datastore.FutureHelper

public final class FutureHelper
extends Object

Utilities for working with Futures in the synchronous datastore api.

Constructor Summary

Constructors

Constructor	Description
FutureHelper()

Method Summary

Modifier and Type	Method	Description
static <T> T	quietGet(Future<T> future)	Return the result of the provided Future, converting all checked exceptions to unchecked exceptions so the caller doesn't have to handle them.
static <T, E extends Exception> T	quietGet(Future<T> future, Class<E> exceptionClass)	Return the result of the provided Future, converting all checked exceptions except those of the provided type to unchecked exceptions so the caller doesn't have to handle them.

Methods inherited from class java.lang.Object

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

Constructor Details

FutureHelper

public FutureHelper()

Method Details

quietGet

public static <T> T quietGet(Future<T> future)

Return the result of the provided Future, converting all checked exceptions to unchecked exceptions so the caller doesn't have to handle them. If an ExecutionException is thrown the cause is wrapped in a RuntimeException. If an InterruptedException is thrown it is wrapped in a DatastoreFailureException.

Type Parameters:

T - The type of the provided Future.

Parameters:

future - The Future whose result we want to return.

Returns:

The result of the provided Future.

quietGet

public static <T,
E extends Exception> T quietGet(Future<T> future,
 Class<E> exceptionClass)
                                           throws E

Return the result of the provided Future, converting all checked exceptions except those of the provided type to unchecked exceptions so the caller doesn't have to handle them. If an ExecutionException is thrown and the type of the cause does not equal exceptionClass the cause is wrapped in a RuntimeException. If the type of the cause does equal exceptionClass the cause itself is thrown. If an InterruptedException is thrown it is wrapped in a DatastoreFailureException.

Type Parameters:

T - The type of the provided Future.

Parameters:

future - The Future whose result we want to return.

exceptionClass - Exceptions of this type will be rethrown.

Returns:

The result of the provided Future.

Throws:

E - Thrown If an ExecutionException with a cause of the appropriate type is caught.