java - Android: thread exiting with uncaught exception -

i have got problem , can't find solution it. when receive data on bluetooth connection, program crashes. receiving data in separate thread each received byte saved in queue. have 1 timertask, calls method read data queue every 1 ms, , refresh textbox in ui. program works while, crashes. please help. here main code snippets.

public class mainactivity extends activity {            textview mylabel1;     volatile boolean stopworker = false;       public queue<byte> receiverqueue = new linkedlist<byte>();     protected byte[] receiverarray;     private boolean newdataread = false;      //timer     timertask mtimertask;     timer timer = new timer();       final handler timerhandler = new handler(); }  @override public void oncreate(bundle savedinstancestate) {  super.oncreate(savedinstancestate); setcontentview(r.layout.activity_main);  mylabel1 = (textview)findviewbyid(r.id.textview1); //start timer ticking after 1 sec, , give timer tick every 1ms  ontimertick(); timer.schedule(mtimertask, 1000, 1);  }   //method reading data receiverqueue protected void readdatafromreceiverbuffer() {     //if receiverqueue not empty, read data     if(receiverqueue.isempty() == false) {         //declaration of byte array receiverfield size of receiverqueue         receiverarray = new byte[receiverqueue.size()];         //read bytes queue until empty             (int = 0; receiverqueue.isempty() == false; i++) {                 //retrieves , removes head of queue, or returns null              receiverarray[i] = receiverqueue.poll();             }         //variable newdata set true, when read new data queue         newdataread = true;     } }          thread datareceivethread = new thread(new runnable() {     //received byte     int receiveddata;     public void run() {         while(!thread.currentthread().isinterrupted() && !stopworker) {              try {                  //read 1 byte inputstream                 receiveddata = mminstream.read();                 //inserts received byte queue if possible                  if(receiveddata != -1)                     receiverqueue.offer((byte)receiveddata);             }             catch (ioexception ex) {                 stopworker = true;             }                        //log.i(string.valueof(receiveddata), "valueofreceiveddata");         }                }        });   public void ontimertick() { mtimertask = new timertask() {     string temp;     //this method called          public void run() {             //call method read data queue             readdatafromreceiverbuffer();             timerhandler.post(new runnable() {                 public void run() {                     //when new data has arrived, update ui                  if(newdataread == true) {                     //convert byte array string                     temp = new string(receiverarray, 0, receiverarray.length);                      mylabel1.settext(temp);                      newdataread = false;                 }                                                    }                 });        }};     }     

logcat:

w/dalvikvm(12358): threadid=11: thread exiting uncaught exception (group=0x40ab1210) e/androidruntime(12358): fatal exception: timer-0 e/androidruntime(12358): java.lang.arrayindexoutofboundsexception: length=21; index=21 e/androidruntime(12358):    @ com.example.colibri2bb.mainactivity.readdatafromreceiverbuffer(mainactivity.java:195) e/androidruntime(12358):    @ com.example.colibri2bb.mainactivity.readdatafromreceiverbuffer(mainactivity.java:195) e/androidruntime(12358):    @ com.example.colibri2bb.mainactivity$3.run(mainactivity.java:230) e/androidruntime(12358):    @ java.util.timer$timerimpl.run(timer.java:284) 

logcat:

w/dalvikvm(17344): threadid=12: thread exiting uncaught exception (group=0x40ab1210) e/androidruntime(17344): fatal exception: timer-1 e/androidruntime(17344): java.util.nosuchelementexception e/androidruntime(17344): atjava.util.linkedlist.removefirstimpl(linkedlist.java:689) e/androidruntime(17344): @ java.util.linkedlist.removefirst(linkedlist.java:676) e/androidruntime(17344): @ java.util.linkedlist.poll(linkedlist.java:895) e/androidruntime(17344):atcom.example.colibri2bb.mainactivity.readdatafromreceiverbuffer(mainactivity.java:196) e/androidruntime(17344): atcom.example.colibri2bb.mainactivity$3.run(mainactivity.java:231) e/androidruntime(17344): @ java.util.timer$timerimpl.run(timer.java:284) 

could other thread modifying receiverqueue , adding data while you're reading it? try using loop instead. should make sure don't go out of bounds.

int queuesize = receiverqueue.size(); receiverarray = new byte[queuesize ]; (int = 0; i<queuesize; i++) {    ... }