How to replace the system.out with Toasts inside a thread

Question

How to add a toast method inside a thread. I want to debug by replacing the system.out with a toast method to display results to the display.

I know that using the application Context from within the thread, like so: Toast.makeText(getApplicationContext(), "help", Toast.LENGTH_LONG).show(); will not work.

I don't know how to use the Runnable with the Toast call and calling runOnUiThread(runnable) from the Thread

Could someone help me out.

public class NetworkServer extends Thread
{

   DatagramSocket mSocket = null;   
   boolean isFinish = false;

   private SimplestPossibleActivity activity;

   public NetworkServer(SimplestPossibleActivity activity)
   {
    this.activity = activity;
   }

   public void run() 
   {

      try 
      {

        Log.d("UDP", "Listening");
        mSocket = new DatagramSocket( 2010); //4444
        mSocket.setBroadcast(true);

        while (!isFinish) 
        {

           Log.d("UDP", "C: socket create success");
           byte[] recvbuffer = new byte[12];
           DatagramPacket packet = new DatagramPacket(recvbuffer,recvbuffer.length);
           Log.d("UDP", "receiving...");
           mSocket.receive(packet);
           Log.d("UDP", "received packet");

           ByteBuffer bb = ByteBuffer.allocate(recvbuffer.length).order(ByteOrder.LITTLE_ENDIAN);
           bb.put(recvbuffer);
           bb.rewind();
           //System.out.println(bb.getFloat());
           //System.out.println(bb.getFloat());
           //System.out.println(bb.getFloat());


           Bundle data = new Bundle();
           data.putFloat("latitude",  bb.getFloat());
           data.putFloat("longitude", bb.getFloat());
           data.putFloat("altitude",  bb.getFloat());

           Message msgHandle = new Message();
           msgHandle.setData(data);
           mhandler.sendMessage(msgHandle);

       } //end while
     } catch (Exception e) {
        Log.e("UDP", "C: Error", e);
     }

   }

   private Handler mhandler = new Handler() 
   {

        @Override
        public void handleMessage(Message msg) 
        {

           Bundle data = msg.getData();
           Log.d("NetworkServer","adding position" + "lat = " + data.getFloat("latitude") +
                                 "lon = " + data.getFloat("longitude") + 
                                 "alt = " + data.getFloat("altitude"));
           activity.addPosition(data.getFloat("latitude"), 
                               data.getFloat("longitude"), 
                               data.getFloat("altitude"));

    }

   };
}

you can use `runOnuiThread`. But `runOnuiThread` is a method of activity class. you cannot update ui on the background thread. ui should be updated on the ui thread — Raghunandan, Aug 16 '13 at 18:39
you cannot show toast on worker thread. You can only use `Handler`, `runOnUiThread()` or `AsyncTask`. — Simon Dorociak, Aug 16 '13 at 19:52

Oleksii K. · Answer 1 · 2015-04-14T10:57:11.507

Use library Xdroid:

dependencies {
    compile 'com.shamanland:xdroid-toaster:0.2.4'
}

There are quite good approaches:

Context variable is not required.
runOnUiThread() is not required.

Just invoke the single method!

// using the resource string
Toaster.toast(R.string.my_msg);
// or hard-coded string
Toaster.toast("Hello Xdroid!");

There are more examples here: https://github.com/shamanland/xdroid-toaster-example

score 1 · Answer 2 · answered Aug 16 '13 at 18:41

1

You can do it like this
Handler handler = new Handler(); //Before your Thread

 //Within your thread
 handler.post(new Runnable(){
                public void run() {
                   Toast.makeText(getApplicationContext(), "help", Toast.LENGTH_LONG).show();
            }
         });

answered Aug 16 '13 at 18:41

Marc-André Therrien

519
5
21

This works only if the handler is started on the main thread. – allprog Aug 16 '13 at 20:03
thanks that worked for me! – Craig P Aug 30 '18 at 09:47

score 0 · Answer 3 · answered Aug 16 '13 at 19:47

0

    runOnUiThread(new Runnable() {
        @Override
        public void run() {
            try {
                //pick one:

                //if activity
                Toast.makeText(YOURACTIVITYNAME.this, "help", Toast.LENGTH_LONG).show();

                //if fragment
                Toast.makeText(getActivity(), "help", Toast.LENGTH_LONG).show();
            } catch (final Exception e) {

            }
        }
    });

answered Aug 16 '13 at 19:47

MrTristan

739
5
17

2

bad idea to catch `Exception` and do nothing – Oleksii K. Jul 17 '14 at 10:23

How to replace the system.out with Toasts inside a thread

3 Answers3

Linked