TimerTask中的NetworkOnMainThreadException

Question

我需要不断地从Android应用程序广播UDP数据包，所以我创建了一个派生自TimerTask的类。当我尝试从TimerTask中更新UI元素时，应用程序崩溃，告诉我它在一个单独的线程上运行。

但是，当我尝试发送UDP数据包时，应用程序因NetworkOnMainThreadException而崩溃。

// simplified
public class UdpDiscoveryTask extends TimerTask {

    private final DatagramSocket _socket;

    public UdpDiscoverytAsk() {
        _socket = new DatagramSocket(PORT);
    }

    @Override
    public void run() {
        DatagramPacket packet = new DatagramPacket("Hello".getBytes().....);
        _socket.send(packet);
    }

}

Answer 1

您是否尝试过使用从TimerTask中重复调用的AsyncTask？

取自this question

public void callAsynchronousTask() {
    final Handler handler = new Handler();
    Timer timer = new Timer();
    TimerTask doAsynchronousTask = new TimerTask() {       
        @Override
        public void run() {
            handler.post(new Runnable() {
                public void run() {       
                    try {
                        PerformBackgroundTask performBackgroundTask = new PerformBackgroundTask();
                        // PerformBackgroundTask this class is the class that extends AsynchTask 
                        performBackgroundTask.execute();
                    } catch (Exception e) {
                        // TODO Auto-generated catch block
                    }
                }
            });
        }
    };
    timer.schedule(doAsynchronousTask, 0, 50000); //execute in every 50000 ms
}

来自@Rasel

Answer 2

@override 
public void run() {

 new SendTask().exectue(null,null,null);
}



 class SendTask extends AsyncTask<Void,Void,Void> {


    public void doInBackground(Void.. params) {

         DatagramPacket packet = new DatagramPacket("Hello".getBytes().....);
    _socket.send(packet);

    }


}