Android简洁代码实现双击退出程序

方法一：重写onBackPressed()方法

 @Override
    public void onBackPressed() {
        if (mBackPressed+TIME_INTERVAL>System.currentTimeMillis()){
            super.onBackPressed();
            return;
        }else {
            Toast.makeText(getApplicationContext(), "再按一次退出程序", Toast.LENGTH_SHORT).show();
        }
        mBackPressed = System.currentTimeMillis();
    }

当然也可以写个其他的定时器来实现，无需判断onKeyDown()和onKeyUp()

So Esay!!!