Back button on Android Phones

A couple questions about the back button (as seen on the emulator)...

1. Do all Android phones have the back button as a hard, tactile button?

2. If so, is it still recommended to put a back button in your software?

3. Is it possible to change the animation between activities when this back button is pressed? I would like it to be consistent with the animatio开发者_运维百科ns in my app.

1. All Android phones have a dedicated BACK button. It is not always a "hard, tactile" button.

2. It is never recommended to put a BACK button in your software.

3. Reportedly, yes, but I do not have the answer handy, sorry.

For 3: Yes.

@Override 
public void onBackPressed() {
    super.onBackPressed();
    overridePendingTransition(R.anim.zoom_enter, R.anim.zoom_exit);
}