Android：恢复singleTask活动

Question

I have an activity with an UDP socket on a port. If I press the Home button the activity goes in background, OnPause() and OnStop() methods are called. Now I want to resume my activity when I receive some UDP packet. Reading the other posts I understand I have to:

1. declare the activity as android:launchMode="singleTask" (or singleInstance )
2. Then, when I want to resume the activity:

Intent intent = new Intent(this.getApplicationContext(), myActivity.class);

intent.addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP | Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_NEW_TASK);

startActivity(intent);

This solution does not work form me. The call to startActivity(intent) does not show my activity on foreground and onResume() is not called.

The following flags do the job but I don't want to clear the task and restart a new one.

intent.addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP | Intent.FLAG_ACTIVITY_CLEAR_TASK | Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);

Answer 1

In order to bring your own task to the foreground, you need to call startActivity() on a non-Activity Context, for example:

getApplicationContext().startActivity(intent);

Also, you don't need to use any special launch mode ( singleTask or singleInstance ) for this to work.

This is an Android bug that was fixed in Android 4.4. Since this question is from 2014, I will assume that OP was seeing this problem.

See How to resume Android Activity programmatically from background and the comment thread.