Android中双击返回键退出应用实例代码

Android中双击返回键退出程序

1.在MyAppliction中(继承Application)

  //运用list来保存们每一个activity是关键
  private List<Activity> mList = new LinkedList<Activity>();
  //为了实现每次使用该类时不创建新的对象而创建的静态对象
  private static MyApplication instance;
  //构造方法
  public MyApplication() {
  }
  //实例化一次
  public synchronized static MyApplication getInstance() {
    if (null == instance) {
      instance = new MyApplication();
    }
    return instance;
  }
  //添加要退出的Activity
  public void addActivity(Activity activity) {
    mList.add(activity);
  }
  //关闭每一个list内的activity
  public void exit() {
    try {
      for (Activity activity : mList) {
        if (activity != null)
          activity.finish();
      }
    } catch (Exception e) {
      e.printStackTrace();
    } finally {
      System.exit(0);
    }
  }
  //杀进程
  public void onLowMemory() {
    super.onLowMemory();
    System.GC();
  }

2.在你需要的关闭的Activity的onCReact()中加入

MyApplication.getInstance().addActivity(this);

3.你需要双击返回退出的界面加上

  
  private long mExitTime;
  public boolean onKeyDown(int keyCode, KeyEvent event) {
    if (keyCode == KeyEvent.KEYCODE_BACK) {
      if ((System.currentTimeMillis() - mExitTime) > 3000) {
        Toast.makeText(this, "再按一次退出程序", Toast.LENGTH_SHORT).show();
        mExitTime = System.currentTimeMillis();
      } else {
        MyApplication.getInstance().exit();
      }
      return true;
    }
    return super.onKeyDown(keyCode, event);
  }

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