如何在Android应用中正常关闭所有活动并关闭所有正在运行的线程？

Question

At the moment, in each one of my activities I have this method:

private void registerReceiverClose(){
    Activity activity = this;
    IntentFilter intentFilter = new IntentFilter();
    intentFilter.addAction("CLOSE_ALL");
    broadcastReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            activity.finish();
        }
    };
    registerReceiver(broadcastReceiver, intentFilter);
}

and this one as well:

@Override
protected void onDestroy() {
    unregisterReceiver(broadcastReceiver);
    super.onDestroy();
}

They're triggered by the following logout button:

    Button logout = findViewById(R.id.logout_button);
    logout.setOnClickListener(click -> {
        Intent intent = new Intent("CLOSE_ALL");
        this.sendBroadcast(intent);
    });

One thing that I'm sure is not closing in the right way, is that I have this code:

private static final ScheduledExecutorService pollingScheduledExecutor = Executors.newSingleThreadScheduledExecutor();

private static final Object lock = new Object();
private static ScheduledFuture<?> currentRunningTask;

public void longPoll() {
    synchronized (lock) {
        if (currentRunningTask != null) {
            currentRunningTask.cancel(true);
        }
        try {
            currentRunningTask = pollingScheduledExecutor.scheduleAtFixedRate(this, 0, 3, TimeUnit.SECONDS);
        } catch (Exception ignored) {
        }
    }
}

public void request() {
    Thread requestThread = new Thread(this);
    requestThread.start();
}

which continues to issue requests even after I think I should be logged out, which causes errors on the server.

How can I make sure all the threads stop gracefully and the application closes down in the right way?

Answer 1

You could wrapthe polling code inside of a Service . This service can then be stopped using

Intent intent = new Intent(MainActivity.this, MyService.class); 
stopService(intent);  

Inside of the service, you can override onDestroy() to clean resources up.