Android back button and resume activity

Issue

I have this issue.
I have an actvity A that starts other activity B (by onclick - button).
In B I have one back button to come back to activity A. I press it.
Now that I'm in A, I press again button to go to B.

If I use android back button (I'm in B) I come back to A first and then to B.
But now, if i press android back button again, I don't go to previus activity of A or it exit from app. I come back to B !!!

How can I prevent this behavior ?

Solution

The back button of activity B should not start activity A, but close activity B with finish: http://developer.android.com/reference/android/app/Activity.html#finish%28%29

Note that it is probably bad user interface design to have a "back" button on the interface. This official Android page says "Don't use labeled back buttons" http://developer.android.com/design/patterns/pure-android.html

Answered By - Rémi