在项目中实施 Google Cast 时如何解决 Task is not yet complete 异常？

Question

I've been working on this for weeks no joke but I'm really stumped at this one part. So I'm in the process of implementing Google Cast into a poorly constructed codebase that I inherited.

Specifically, I'm using this source as reference since the codebase was written entirely in Java for some arbitrary reason: https://github.com/googlecast/CastVideos-android

And to be more specific, all I'm trying to do right now is get the

mCastContext = CastContext.getSharedInstance(this,localExecutor).getResult();

line in VideoBrowserActivity to work in my project. However, I am getting this error when implementing it but not when I run the other project: Unable to start activity ComponentInfo{}: java.lang.IllegalStateException: Task is not yet complete

Here are the important parts of my work and the reference file, respectively:

public class VideoExoPlayerActivity extends BaseActivity implements OnClickHandlerInterface {

    private ActivityVideoExoPlayerBinding binding;
    private VideoPlayerViewModel viewModel;

    private String videoUuid;
    private ExoPlayer exoPlayer;
    private DefaultTrackSelector trackSelector;
    private String drmLicenseUrl;
    private String mimeType;
    private Boolean isDashDRM;

    private AudioManager manager;
    private boolean isScreenLock = false;
    private boolean isShortVideo = false;
    private boolean isRollOverVideoAvailable = false;
    private boolean isRollOverShow = false;
    private boolean isRollOverDismiss = false;

    private int currentPosition = 0;
    private int continuePosition = -1;
    private List<VideoUuidURLModel> list_url = new ArrayList<>();
    private List<VideoPlayerDataResponse.Data> list_video = new ArrayList<>();
    private PictureInPictureParams.Builder mPictureInPictureParamsBuilder;

    private CastContext mCastContext;
    private CastSession mCastSession;
    private MediaRouteButton mMediaRouteButton;
    private SessionManager mSessionManager;
    private SessionManagerListener<CastSession> mSessionManagerListener =
            new SessionManagerListenerImpl();
    private Executor localExecutor = Executors.newSingleThreadExecutor();


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        binding = DataBindingUtil.setContentView(this, R.layout.activity_video_exo_player);
        viewModel = new ViewModelProvider(this, new CommonFactory<>(this)).get(VideoPlayerViewModel.class);

        mCastContext = CastContext.getSharedInstance(this, localExecutor).getResult();

        initView();
        hideStatusBar();
        startService(new Intent(this, HistoryAPIBackgroundService.class));
    }

public class VideoBrowserActivity extends AppCompatActivity {

    private static final String TAG = "VideoBrowserActivity";
    private CastContext mCastContext;
    private final SessionManagerListener<CastSession> mSessionManagerListener =
            new MySessionManagerListener();
    private CastSession mCastSession;
    private MenuItem mediaRouteMenuItem;
    private MenuItem mQueueMenuItem;
    private Toolbar mToolbar;
    private IntroductoryOverlay mIntroductoryOverlay;
    private CastStateListener mCastStateListener;
    private Executor localExecutor = Executors.newSingleThreadExecutor();

    private class MySessionManagerListener implements SessionManagerListener<CastSession> {

        @Override
        public void onSessionEnded(CastSession session, int error) {
            if (session == mCastSession) {
                mCastSession = null;
            }
            invalidateOptionsMenu();
        }

        @Override
        public void onSessionResumed(CastSession session, boolean wasSuspended) {
            mCastSession = session;
            invalidateOptionsMenu();
        }

        @Override
        public void onSessionStarted(CastSession session, String sessionId) {
            mCastSession = session;
            invalidateOptionsMenu();
        }

        @Override
        public void onSessionStarting(CastSession session) {
        }

        @Override
        public void onSessionStartFailed(CastSession session, int error) {
        }

        @Override
        public void onSessionEnding(CastSession session) {
        }

        @Override
        public void onSessionResuming(CastSession session, String sessionId) {
        }

        @Override
        public void onSessionResumeFailed(CastSession session, int error) {
        }

        @Override
        public void onSessionSuspended(CastSession session, int reason) {
        }
    }

    /*
     * (non-Javadoc)
     * @see android.support.v4.app.FragmentActivity#onCreate(android.os.Bundle)
     */
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.video_browser);
        setupActionBar();

        mCastStateListener = new CastStateListener() {
            @Override
            public void onCastStateChanged(int newState) {
                if (newState != CastState.NO_DEVICES_AVAILABLE) {
                    showIntroductoryOverlay();
                }
            }
        };
        mCastContext = CastContext.getSharedInstance(this,localExecutor).getResult();
    }

There are some things in mine that look to be missing, but I've tried implementing everything you can see already and nothing has changed my result. Please ask if you need to see other parts of the code because I have no idea if this problem could be coming from somewhere else. From what I can tell, there are next to no tutorials about implementing this in Java so I'm doing it very blind and it has been very difficult so I really appreciate any help I can get.

Answer 1

The "Task is not yet complete" exception is usually thrown when a task has not yet completed and its result is being accessed. This can occur when working with asynchronous tasks, such as those that involve network or I/O operations.

To resolve this exception when implementing Google Cast into a project, you will need to ensure that the task has completed before accessing its result. This can typically be done by using a callback or a listener to get notified when the task has completed.

Here is an example of how you could implement a callback to resolve the "Task is not yet complete" exception:

private void doSomeTask() {
  // Start the task and pass a callback to be called when the task is complete
  someTask.start(new SomeTask.Callback() {
    @Override
    public void onTaskComplete(Result result) {
      // The task is complete, so we can access the result here
      processResult(result);
    }
  });
}

private void processResult(Result result) {
  // Do something with the result
}

Alternatively, you could use a listener to get notified when the task is complete:

private void doSomeTask() {
  // Set a listener to be called when the task is complete
  someTask.setListener(new SomeTask.Listener() {
    @Override
    public void onTaskComplete(Result result) {
      // The task is complete, so we can access the result here
      processResult(result);
    }
  });
  // Start the task
  someTask.start();
}

private void processResult(Result result) {
  // Do something with the result
}

By using a callback or listener, you can ensure that the task has completed before accessing its result, which should help resolve the "Task is not yet complete" exception.

here is an example of how you can use the addOnSuccessListener method to get the shared instance of CastContext:

CastContext.getSharedInstance(this, localExecutor)
        .addOnSuccessListener(new OnSuccessListener<CastContext>() {
            @Override
            public void onSuccess(CastContext castContext) {
                // The task was successful, and you can get the shared instance of CastContext here
                mCastContext = castContext;
                // Now you can use mCastContext
            }
        });

Here, this is the ApplicationContext and localExecutor is the Executor that you want to use to execute the tasks associated with CastContext.

To use the await() method, you can do the following:

mCastContext = CastContext.getSharedInstance(this, 
localExecutor).await().getResult();

Here, await() blocks the current thread until the task is complete. The getResult() method then returns the result of the task, which is the shared instance of CastContext.

I hope this helps!

Answer 2

This doesn't answer your question directly as to why your app behaves differently than the google cast reference app but you can add OnCompleteListener then set the context:

Kotlin:

CastContext.getSharedInstance(this, castExecutor).addOnCompleteListener {
    castContext = it.result
    castContext?.addCastStateListener(this)
}

Java:

Task task = CastContext.getSharedInstance(this,localExecutor);
task.addOnCompleteListener(task1 -> mCastContext = (CastContext) task1.getResult());
        
        // or 

Task task = CastContext.getSharedInstance(this,localExecutor);
task.addOnCompleteListener(new OnCompleteListener() {
            @Override
            public void onComplete(@NonNull Task task) {
                mCastContext = (CastContext)task.getResult();
            }
        });

I am stuck at the same point (much of today) as yourself trying to figure out why the CastContext.getSharedInstance(this, castExecutor).result gives the "Task is not yet complete" exception in my own app but not the reference app even though I have followed the same steps as far as I can tell.