Bring task to front on android.intent.action.USER_PRESENT

Question

BACKGROUND
I have a task (i.e. app) with multiple activities.

QUESTION
How do I bring a task to the front w/o re-ordering

Answer 1

Here's a slightly hackish implementation that works for me:

• Create a simple BringToFront activity that simply finish() itself on its onCreate():

  public class BringToFront extends Activity {
  
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          finish();
      }
  
  }
  

• In your BroadcastReceiver, start the BringToFront activity above instead of your activity_A if the action is USER_PRESENT:

  @Override
  public void onReceive(Context context, Intent intent) {
      Class<? extends Activity> activityClass = activity_A.class;
  
      if (intent.getAction().equals(Intent.ACTION_USER_PRESENT)) {
          activityClass = BringToFront.class;
      }
  
      Intent i = new Intent(context, activityClass);
      i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
      context.startActivity(i);
  }
  

This works because the BringToFront activity has the same taskAffinity as your activity_A and starting it will make the system bring the existing task to the foreground. The BringToFront activity then immediately exit, bringing the last activity on your task (activity_B in your scenario) to the front.

It's worth noting that on API level 11 (Honeycomb), a moveTaskToFront() method is added to the system's ActivityManager service that might probably be the better way to achieve what you want.

Answer 2

Ok, I was able to get this to work by adding a static global variable in my main activity (activity_A). In onCreate I set isRunning = true, and onDestory = false. Then in my IntentReceiver class I check the isRunning to determine which activity to start:

            :
    if (intent.getAction().equals(Intent.ACTION_USER_PRESENT)) {
        if (GlobalVariables.isRunning) {
            activityClass = BringToFront.class;
        } else {
            activityClass = activity_A.class;
        }
    } else if (intent.getAction().equals(Intent.ACTION_BOOT_COMPLETED)) {
        activityClass = activity_A.class;
    }
            :