Android: Control which activity is shown when clicking notification

Question

In an Android app, I have two activities; lets call them A and B. A is the main activity, and it contains a button that calls startActivity() to display B. In short:

A -> B

A has a thread that ticks every minute. On this tick, a notification is updated in the status bar

This is what I am after:

1) When the user clicks the notification when neither A nor B is visible, show A 2) When the user clicks the notification when A is visible, nothing should happen 3) When the user clicks the notification when B is visible, nothing should happen (or, if it is easier, pop B to show A)

1) and 2) are easy to accomplish. 3) will start a new version of A and add it to the queue:

A -> B -> A, which is not what I intended. The user has to press back three times to go to the home screen

Is there a way to ensure that clicking the notification will either show the stack A -> B or A alone?

Answer 1

You should set the flag of activity A to singleTask and catch the new startActivity() intent to the onNewIntent(Intent i) of activity A (which you should override). Hope this helps!

Answer 2

Set FLAG_ACTIVITY_CLEAR_TOP flag in startActivity() method. After that, if you want to recreate activity A, set FLAG_ACTIVITY_SINGLE_TOP flag. Or if you want to reuse activity A, set FLAG_ACTIVITY_SINGLE_TOP flag.