常规双击回退键退出程序

需求：点击一次提示，再次点击退出程序。

在主antivity中加入这段代码便可：

private boolean isExit = false;private Handler mHandler = new Handler() {    @Override    public void handleMessage(Message msg) {        super.handleMessage(msg);        isExit = false;    }};@Overridepublic boolean onKeyDown(int keyCode, KeyEvent event) {    if (keyCode == KeyEvent.KEYCODE_BACK) {        if (!isExit) {            isExit = true;            Toast.makeText(mContext, "再次点击退出", Toast.LENGTH_SHORT).show();            mHandler.sendEmptyMessageDelayed(1,3000);        } else {            finish();        }        return false;    }    return super.onKeyDown(keyCode, event);}