Consuming Keydown Events

The last few weeks have been very hectic for me. I am working on my first Android and iPhone projects simultaneously and anyone will tell you that is not fun :-).

Anyway, while working on an Android app, I came across a small problem that really annoyed me. I was displaying a modal dialog and I did not want the user to navigate away from the modal dialog unless they clicked an 'OK' button.

But then I saw a problem. All the user had to do was press either the back button, the home button or the call buttons and the dialog disappeared. Now that is not what I intended or wanted and in the interest of self preservation, I started wondering how to solve the problem and thankfully found a very easy solution.

All I had to do was consume the keydown events for those buttons by overriding the onKeyDown method in my dialog class.

@Ovveride
public boolean onKeyDown(int keyCode, KeyEvent event) {
switch (keyCode) {
case KeyEvent.KEYCODE_BACK:
  return true;
case KeyEvent.KEYCODE_CALL:
  return true;
case KeyEvent.KEYCODE_DPAD_CENTER :
  return true;
case KeyEvent.KEYCODE_ENDCALL
   return true;
case KeyEvent.KEYCODE_HOME: // this does not work.
    return true;
default:
   break;
}
// pass all unhandled events to the parent class
return super.onKeyDown(keyCode, event);
}

That is it. I could now prevent users from clicking on these buttons and navigating away from the dialog.

This can be used to disable users from pressing any other buttons you don't want them to. The only exception is the 'Home' button. I am not sure if there is any other way, but this approach certainly does not work. You can find a more detailed reference on all available key event constants here.