android - Java Thread Concurrent Read and Write -

i have arraylist store data received , transmit asynchronously on bluetooth.

i have write thread , read thread access arraylist. trying simulate bluetooth echo (the bluetooth echo send).

private class readthread extends thread { @override public void run() {     super.run();         while(!isinterrupted()) {              try {                 byte[] buffer = new byte[64];                 if (minputstream == null) return;                 size = minputstream.read(buffer);                 if (size == 64) {                     if (bufferlist.isempty()){                         log.i("aok fail","nothing aok");                     }                      if (comparebyte(buffer,bufferlist.get(0) == true) // compare data in 2 byte array                           bufferlist.remove(0);                 }             } catch (ioexception e) {             e.printstacktrace();             return;         }     } } }  private class writethread extends thread {     @override     public void run() {     super.run();     while(!isinterrupted()) {          try {             count++;             if (bufferlist.isempty() == false && count < 3){                     write(bufferlist.get(0));                        count = 0;             }else{                 // drop data after 3 fail attempt                 bufferlist.remove(0);                 count=0;             }                             thread.sleep(500);         } catch (ioexception e) {             e.printstacktrace();             return;         }     } } } 

on button pressed send data . works fine if transmit slowly. fails when start click rapidly (queue data transmission). once received aok fail message . remaining data aok fail newly add data. why

if threading issue shouldn't resolve after data transmitted ?

this bufferlist variable thread safe object? array blocking list or something? if not may having problems trying add/remove itens simultaneously.

this cause exception in producer thread, nothing else transmitted you'd "nothing aok" log.