Android 实现两次点击返回键 提示退出

方法一

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// 用来计算返回键的点击间隔时间 private long exitTime = 0; @Override public boolean onKeyDown(int keyCode, KeyEvent event) { if (keyCode == KeyEvent.KEYCODE_BACK && event.getAction() == KeyEvent.ACTION_DOWN) { if ((System.currentTimeMillis() - exitTime) > 2000) { //弹出提示，可以有多种方式 Toast.makeText(getApplicationContext(), "再按一次退出程序", Toast.LENGTH_SHORT).show(); exitTime = System.currentTimeMillis(); } else { finish(); } return true; } return super.onKeyDown(keyCode, event); }

 来自CODE的代码片

Android-实现两次点击返回键-提示退出.txt

  方法二

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// 定义一个变量，来标识是否退出 private static boolean isExit = false; Handler mHandler = new Handler() { @Override public void handleMessage(Message msg) { super.handleMessage(msg); isExit = false; } }; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); } @Override public boolean onKeyDown(int keyCode, KeyEvent event) { if (keyCode == KeyEvent.KEYCODE_BACK) { exit(); return false; } return super.onKeyDown(keyCode, event); } private void exit() { if (!isExit) { isExit = true; Toast.makeText(getApplicationContext(), "再按一次退出程序", Toast.LENGTH_SHORT).show(); // 利用handler延迟发送更改状态信息 mHandler.sendEmptyMessageDelayed(0, 2000); } else { finish(); System.exit(0); } }

 来自CODE的代码片