Make the “up” button behave like the “back” button

问题:

The Android app design I'm working with calls for the "Up" button to behave the same way the "Back" button behaves, but I'm not sure how to make that happen.

I know that android:parentActivityName must be specified for the "Up" button to be visible on an activity, but specifying a fixed parent activity doesn't really make sense for the activity. Imagine this scenario with activities A, B, and C:

1. Launch into activity A, it contains two buttons: each taking you to activities B and C, respectively.
2. Tap the button for activity B.
3. Transition to activity B. it contains two buttons: each taking you to activities A and C, respectively.
4. Tap the button for activity C.
5. Transition to activity C.
6. Tap the "up" button, you should be taken to activity B.
7. On activity B now: tap the button for activity A.
8. Transition to activity A.
9. Tap the "up" button, you should be taken to activity B.
10. On activity B Tap the "up" button, you should be taken to activity A.
11. On activity A now: tap the button for activity C.
12. Transition to activity C.
13. Tap the "up" button, you should be taken to activity A.

If I were to specify android:parentActivityName for each activity, it might make sense to have B and C's parent activity be A, but this means that each time we hit the "up" button from activities B or C, we land at activity A (and that's not always what is supposed to happen).

Does anybody have experience with this type of thing?

回答1:

from all three of your activities add the following

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
        case android.R.id.home:
            onBackPressed();
            return true;
    }

    return(super.onOptionsItemSelected(item));
}

when you press the up button on your app it will invoke onOptionsItemSelected with the id of android.R.id.home just catch that case and manually call onBackPressed()