Understanding android UDP server app code -

i'm novice both android , java. i'm trying develop simple udp server first android app (the second 1 if consider hello world!). i've collected code web , result:

package com.example.androidsocketserver;   import java.net.datagrampacket; import java.net.datagramsocket; import android.app.activity; import android.widget.textview;   public class mainactivity extends activity {  public void updatetextview(string tothis) {      textview textview = (textview) findviewbyid(android.r.id.text2);     textview.settext(tothis);      }  private mydatagramreceiver mydatagramreceiver = null;  protected void onresume() {     mydatagramreceiver = new mydatagramreceiver();     mydatagramreceiver.start(); }  protected void onpause() {     mydatagramreceiver.kill(); }  private class mydatagramreceiver extends thread {     private boolean bkeeprunning = true;       public void run() {         string message;         byte[] lmessage = new byte[200];         datagrampacket packet = new datagrampacket(lmessage, lmessage.length);          try {             datagramsocket socket = new datagramsocket(2500);               while(bkeeprunning) {                 socket.receive(packet);                 message = new string(lmessage, 0, packet.getlength());                                   if (message != null) {                     updatetextview(message);                     message = null;                 }                    }             if (socket != null) {                 socket.close();             }         } catch (throwable e) {             e.printstacktrace();         }       }      public void kill() {          bkeeprunning = false;     }   } } 

unfortunately application stopped launch it, don't understand why.
there kind me understand missed. tryed emulator , real device obtaining same result.

thank in advance.

whithout error difficult know fault try changing receiver class async task

public class receiverbroadcastasynctask extends asynctask<void, integer ,string > { boolean running = true; context context; //public int counter = 1; public receiverbroadcastasynctask(context context) {     this.context = context.getapplicationcontext(); }  @override protected string doinbackground(void... params) { /////here code } protected void onpostexecute(string result) {     //do whatever...nothing required pass result on finish } protected void onprogressupdate(integer... progress) { ///you can pass data on here on task progress inform status  } } 

from activity can call async task

new receiverbroadcastasynctask(this).execute(); ///this refers context