PendingResult

public abstract class PendingResult extends Object

Known Direct Subclasses Batch, OptionalPendingResult<R extends Result> Batch Handles a batch of PendingResult items.  OptionalPendingResult<R extends Result> OptionalPendingResults are PendingResults with additional support for non-blocking accessors.

Represents a pending result from calling an API method in Google Play services. The final result object from a PendingResult is of type R, which can be retrieved in one of two ways.

• via blocking calls to await(), or await(long, TimeUnit), or
• via a callback by passing in an object implementing interface ResultCallback to setResultCallback(ResultCallback ).

After the result has been retrieved using await() or delivered to the result callback, it is an error to attempt to retrieve the result again. It is the responsibility of the caller or callback receiver to release any resources associated with the returned result. Some result types may implement Releasable, in which case release() should be used to free the associated resources.

Public Constructor Summary

PendingResult()

Public Method Summary

abstract R	await() Blocks until the task is completed.
abstract R	await(long time, TimeUnit units) Blocks until the task is completed or has timed out waiting for the result.
abstract void	cancel() Requests that the PendingResult be canceled.
abstract boolean	isCanceled() Indicates whether the pending result has been canceled either due to calling disconnect() or calling cancel() directly on the pending result or an enclosing Batch.
abstract void	setResultCallback(ResultCallback<? super R> callback) Set the callback here if you want the result to be delivered via a callback when the result is ready.
abstract void	setResultCallback(ResultCallback<? super R> callback, long time, TimeUnit units) Set the callback here if you want the result to be delivered via a callback when the result is ready or has timed out waiting for the result.
<S extends Result> TransformedResult<S>	then(ResultTransform<? super R, ? extends S> transform) Transforms the result by making another API call.

Inherited Method Summary

From class java.lang.Object

Object	clone()
boolean	equals(Object arg0)
void	finalize()
final Class<?>	getClass()
int	hashCode()
final void	notify()
final void	notifyAll()
String	toString()
final void	wait(long arg0, int arg1)
final void	wait(long arg0)
final void	wait()

Public Constructors

public PendingResult ()

Public Methods

public abstract R await ()

Blocks until the task is completed. This is not allowed on the UI thread. The returned result object can have an additional failure mode of INTERRUPTED.

public abstract R await (long time, TimeUnit units)

Blocks until the task is completed or has timed out waiting for the result. This is not allowed on the UI thread. The returned result object can have an additional failure mode of either INTERRUPTED or TIMEOUT.

public abstract void cancel ()

Requests that the PendingResult be canceled. If the result is available, but not consumed it will be released. If the result is set after cancelation was requested it is immediately released.

onResult(Result) will never be called, await() will return a failed result with CANCELED.

public abstract boolean isCanceled ()

Indicates whether the pending result has been canceled either due to calling disconnect() or calling cancel() directly on the pending result or an enclosing Batch.

public abstract void setResultCallback (ResultCallback<? super R> callback)

Set the callback here if you want the result to be delivered via a callback when the result is ready.

public abstract void setResultCallback (ResultCallback<? super R> callback, long time, TimeUnit units)

Set the callback here if you want the result to be delivered via a callback when the result is ready or has timed out waiting for the result. The returned result object can have an additional failure mode of TIMEOUT.

public TransformedResult<S> then (ResultTransform<? super R, ? extends S> transform)

Transforms the result by making another API call.

If the result is successful, then onSuccess(R) will be called to make the additional API call that yields the transformed result. If the result is a failure, then onFailure(Status) will be called to (optionally) allow modification of failure status.

If the result implements Releasable, then release() will be called once the transform has been applied.

Multiple API calls can be chained together by making subsequent calls to then(ResultTransform ) and the final result can be received by an instance of ResultCallbacks specified via andFinally(ResultCallbacks ). For example:

 final DriveFolder rootFolder = Drive.DriveApi.getRootFolder(mApiClient);
 Drive.DriveApi.newDriveContents(mApiClient)
          .then(new ResultTransform<DriveContentsResult, DriveFileResult>() {
              @Override
              public PendingResult<DriveFileResult> onSuccess(DriveContentsResult result) {
                  DriveContents driveContents = result.getDriveContents();

                  // Write content to DriveContents
                  OutputStream outputStream = driveContents.getOutputStream();
                  PrintWriter writer = new PrintWriter(outputStream);
                  writer.write("Hello World!");
                  writer.close();

                  MetadataChangeSet changeSet = new MetadataChangeSet.Builder()
                          .setTitle("hello.txt")
                          .setMimeType("text/plain")
                          .build();

                  // Create a file on root folder
                  return rootFolder.createFile(mApiClient, changeSet, driveContents);
              }
          })
          .then(new ResultTransform<DriveFileResult, MetadataBufferResult>() {
              @Override
              public PendingResult<MetadataBufferResult> onSuccess(DriveFileResult result) {
                  // Fetch the updated root folder contents
                  return rootFolder.listChildren(mApiClient)
              }
          })
          .andFinally(new ResultCallbacks<MetadataBufferResult>() {
              @Override
              public void onSuccess(MetadataBufferResult result) {
                  // All API calls were successful.
              }

              @Override
              public void onFailure(Status status) {
                  // An API call failed.
              }
          });
 

All ResultTransforms will be run on a worker thread. These transforms therefore must not interact with UI elements, but they may perform brief background work (not requiring more than a few seconds). If ResultCallbacks are specified, these will be called on the thread specified by setHandler(Handler) or on the main thread by default.

If disconnect() is called before a series of transforms completes the transforms will continue to run in the background until the last one completes. In this case, ResultCallbacks will not be called. Note that this may cause memory leaks if background transformations are long-running. For long background tasks, consider using an IntentService.

Note: it is an error to use multiple GoogleApiClients for various API calls within subsequent ResultTransforms. Behavior is undefined if calls don't use the same GoogleApiClient.