Android 双击退出程序

//记录用户首次点击返回键的时间
private long firstTime = 0;

/**
 * 第一种解决办法 通过监听keyUp
 * @param keyCode
 * @param event
 * @return
 */
@Override
public boolean onKeyUp(int keyCode, KeyEvent event) {
    if (keyCode == KeyEvent.KEYCODE_BACK && event.getAction() == KeyEvent.ACTION_UP) {
        long secondTime = System.currentTimeMillis();
        if (secondTime - firstTime > 2000) {
            Toast.makeText(HomePageActivity.this, "再按一次退出程序", Toast.LENGTH_SHORT).show();
            firstTime = secondTime;
            return true;
        } else {
            System.exit(0);
        }
    }

    return super.onKeyUp(keyCode, event);
}