How do I get the status from the Task<Void> returned by ConnectionsClient methods?

Question

I am using the ConnectionsClient API, including startAdvertising(), which returns a Task<Void>. The javadoc for startAdvertising() includes this statement:

Possible result status codes include:

• STATUS_OK if advertising started successfully.
• STATUS_ALREADY_ADVERTISING if the app is already advertising.
• STATUS_OUT_OF_ORDER_API_CALL if the app is currently connected to remote endpoints; call stopAllEndpoints() first.

How do I get these status values after calling startAdvertising()?

I know that the Task API enables me to create an OnSuccessListener and OnFailureListener, but I want to be able to distinguish among different failure cases (specifically, STATUS_ALREADY_ADVERTISING is a benign failure). Because the type is Task<Void>, calling getResult() when it is passed to the onSuccess() method doesn't provide useful information.

Answer 1

Here's a helper method for converting a Task into a status code. This example method is blocking but it would look similar for when asynchronous. The try/catch maps directly to OnSuccessListener/OnFailureListener.

import static com.google.android.gms.common.api.CommonStatusCodes.ERROR;
import static com.google.android.gms.common.api.CommonStatusCodes.SUCCESS;

import android.support.annotation.CheckResult;
import com.google.android.gms.common.api.ApiException;
import com.google.android.gms.tasks.Task;
import com.google.android.gms.tasks.Tasks;
import java.util.concurrent.ExecutionException;

@CheckResult
public static int waitForTask(String methodName, Task<?> task) {
  try {
    Tasks.await(task);
    return SUCCESS;
  } catch (InterruptedException | ExecutionException e) {    
    if (e instanceof InterruptedException) {
      Thread.currentThread().interrupt();
    }

    Exception taskException = task.getException();
    if (taskException instanceof ApiException) {
      return ((ApiException) taskException).getStatusCode();
    }

    return ERROR;
  }
}