brief introduction

One of the common requirements in development is to exit the application. Now, there are two situations. One is to click the return key to pop up a prompt box, to exit the application, such as UC browser and Cheetah browser. The other is to double-click within a certain time interval to exit the application. Generally, it is mainly written in baseactivity (parent class)

What we do today is to exit the application in the second way.
Of course, there are many ways to do this. Here are two ways:

code analysis

1. Directly use System.currentTimeMillis() to judge

private long exitTime = 0;

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) { 
   /*Judge whether the user clicks the "return key"*/
    if (keyCode == KeyEvent.KEYCODE_BACK)

    {
        if ((System.currentTimeMillis() - exitTime) > 2000) {
            Toast.makeText(this, "Press again to exit the program", Toast.LENGTH_SHORT).show();
            exitTime = System.currentTimeMillis();
        } else {
            finishAll();
            System.exit(0);
            Process.killProcess(Process.myPid());
        }
        return true;
    }
    return super.onKeyDown(keyCode, event);
}

2. Use Timer to judge time interval

@Override
 public boolean onKeyDown(int keyCode, KeyEvent event) {
   if(keyCode==KeyEvent.KEYCODE_BACK){
     exitAPP();
   }
     return false;
 }

private boolean isExitApp;
private void exitAPP() {
    Timer timer = null;
    if (!isExitApp) {
        isExitApp = true;
        Toast.makeText(this, "Press again to exit the program", Toast.LENGTH_SHORT).show();
        timer = new Timer();
        timer.schedule(new TimerTask() {
            @Override
            public void run() {
                isExitApp = false;//Cancel exit
            }
        }, 2000);// If the return key is not pressed within 2 seconds, start the timer to cancel the task just executed
    } else {
        finishAll();
        System.exit(0);
        Process.killProcess(Process.myPid());
    }
}

//finish all when the added parent class exits
public static void finishAll() {
    List<BaseActivity> copy;
    synchronized (mActivities) {
        copy = new ArrayList<BaseActivity>(mActivities);
    }
    for (BaseActivity activity : copy) {
        activity.finish();
    }
}

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