Press Again to Exit

PressAgainToExit.java

 private long lastPressedTime;
    private static final int PERIOD = 2000;

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (event.getKeyCode() == KeyEvent.KEYCODE_BACK) {
            switch (event.getAction()) {
                case KeyEvent.ACTION_DOWN:
                    if (event.getDownTime() - lastPressedTime < PERIOD) {
                        finish();
                    } else {
                        Toast.makeText(getApplicationContext(), "Press again to exit.",
                                Toast.LENGTH_SHORT).show();
                        lastPressedTime = event.getEventTime();
                    }
                    return true;
            }
        }
        return false;
    }