Handling the Back Button

Question

I am working on the following code:

private class HandleBackButton implements OnKeyListener
    {

        @Override
        public boolean onKey(View arg0, int arg1, KeyEvent arg2) {
            // TODO Auto-generated method stub

            if(arg1==KeyEvent.KEYCODE_BACK)
            {
                showResults(0);
            }
            return true;
        }

    }

I am somewhat new to android and my purpose is to operate the above code when the back button is clicked. User can click the back button any time. But, how can I set this listener to the Activity? I can't find something like this.setOnKeyListener().

I am using Android 2.3.3.

Answer 1

Just override the onKeyDown() method of Activity. You don't have to set a listener then.

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if(keyCode == KeyEvent.KEYCODE_BACK)
        {
            showResults(0);
            return true;
        }
        return super.onKeyDown(keyCode, event);
    }

Optionally you can also override onBackPressed() if your api level is >= 5.