multithreading - Multithreaded code in Java with ExecutorService fails to return, why? -

i have similar multithreaded code elsewhere in codebase works fine, can't see quite what's going wrong here.

this simple multi-threaded process generate result xml search query. output of running method is:

returning threads

the line system.out.println("finished multithreading loop");" never reached.

modifying number of threads doesn't help.

private void fillallresults() {         int threads = 2;         final futuretask[] tasks = new futuretask[threads];         final executorservice executor = executors.newcachedthreadpool();         (int = 0; < allresults.size(); i++) {             tasks[i] = new futuretask<integer>(new callable<integer>() {                 public integer call() throws exception {                     int index;                     while ((index = getresultsindex()) < allresults.size()) {                         system.out.println("processing result " + index);                          result result = allresults.get(index);                         fillresultxml(result);                     }                     system.out.println("returning threads");                     return 1;                 }             });             executor.execute(tasks[i]);         }         (int = 0; < threads; i++) {             try {                 tasks[i].get();             } catch (interruptedexception e) {                 e.printstacktrace();             } catch (executionexception e) {                 e.printstacktrace();             }         }         executor.shutdown();          system.out.println("finished multithreading loop");     } 

edit, quick replies! here's answers:

it shows 'processing result' many times have results. if allresults.size() 25, shows processing result 1, processing result 2 ... processing result 24.

here's code that's missing:

private list<result> allresults = new arraylist<result>(); private int resultsindex = 0;  private synchronized int getresultsindex() { return resultsindex++; } 

and in case anyone's wondering, can guarantee none of code within loop increases size of allresults.

i suppose related fact, array tasks has length of threads (i.e. 2 in case) assign more values within lines

for (int = 0; < allresults.size(); i++) {     tasks[i] = ...     .... } 

if list allresults has more 2 entries thread stopped arrayindexoutofboundsexception. maybe catch 1 not handle outside code presented.