dispatchKeyEvent,getKeyCode,getAction,getRepeatCountgetKeyDispatcherState

@Override
public boolean dispatchKeyEvent(KeyEvent event) {
    if (event.getKeyCode() == KeyEvent.KEYCODE_BACK) {
        if (event.getAction() == KeyEvent.ACTION_DOWN
                && event.getRepeatCount() == 0) {

            // Tell the framework to start tracking this event.
            getKeyDispatcherState().startTracking(event, this);
            return true;

        } else if (event.getAction() == KeyEvent.ACTION_UP) {
            getKeyDispatcherState().handleUpEvent(event);
            if (event.isTracking() && !event.isCanceled()) {

                // DO BACK ACTION HERE
                return true;

            }
        }
        return super.dispatchKeyEvent(event);
    } else {
        return super.dispatchKeyEvent(event);
    }
}