My Android application uses a thread to listen for a sockets connection from a

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Asked: June 7, 20262026-06-07T08:25:55+00:00 2026-06-07T08:25:55+00:00

My Android application uses a thread to listen for a sockets connection from a

0

My Android application uses a thread to listen for a sockets connection from a PC connected via USB. At some point after the PC opens the connection (in response to some user driven event) I want to send some data over it.

public void onCreate(Bundle savedInstanceState) {

    // SNIP: stuff and nonsense

    connection = new Thread(new ServerThread());
    connection.start();
}

public boolean onTouchEvent(MotionEvent event) {

    // SNIP: decide what to do; create string 'coordString'

    Message coordMsg = coordHandler.obtainMessage();
    Bundle coordMsgData = new Bundle();
    coordMsgData.putString("coords", coordString);
    coordMsg.setData(coordMsgData);
    if(coordHandler!=null)
    {
        coordHandler.sendMessage(coordMsg);
    }

    return false;
}

public class ServerThread extends Thread
{   
    public void run() {

        this.setName("serverThread");

        Looper.prepare();

        coordHandler = new Handler()
        {
            @Override
            public void handleMessage(Message msg) {
                Log.v(INNER_TAG,"here");
            }
        };

        // SNIP: Connection logic here

        Looper.loop();
    }
}.

For ages I was scratching my head wondering why I never saw the value of INNER_TAG appear in my logs after touch events. I could use log-debugging to trace the execution into the coordHandler!=null block, but the handler never seemed to fire.

Then it struck me: the thread is probably exiting after completing the connection. D’uh! Not quite sure what I thought was happening before, but I’ll blame it on a belief that Loop was doing something magical.

So my question is: How can I keep my thread running? The official Android dev reference on threads briefly mentions that

A Thread can also be made a daemon, which makes it run in the background.

This naturally made my *nix senses tingle. (Incidentally, have you seen the new Spiderman film yet? It’s pretty good.) Is daemonisation the answer? Or have I completely lost the plot?