How to catch device back button event in android?

Question

I have open pdf file through my application.when click on device back button it is automatically come back to my application .It is working fine.Here i want catch back button event in device.I override the back button.but it is not working.please help me.

Answer 1

This is an example of what you are asking:

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    if (keyCode == KeyEvent.KEYCODE_BACK ) {
        //do your stuff
    }
    return super.onKeyDown(keyCode, event);
}

Answer 2

just call the foolowing function this will close current activity and move you to the previous screen

finish();