Android连续点击返回键退出应用

@Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (event.getKeyCode() == KeyEvent.KEYCODE_BACK) {
            if ((System.currentTimeMillis() - exitTime) > 2000) {
                Toast.makeText(MainActivity.this, "再按一次退出程序", Toast.LENGTH_SHORT).show();
                exitTime = System.currentTimeMillis();
            } else {
                finish();
            }
        }
        return true;
    }

只需在activity中重写onKeyDown（）方法即可

转载自https://blog.csdn.net/onlyonecoder/article/details/8631344