Template: Multithreading solution using Executors

TEMPLATE: Thread Executors

Solution 1: No wait.

This is simple template to run multithreaded solution, where you don't need to wait for responses.

       public void start() {

              ExecutorService executor = Executors

                           .newFixedThreadPool(CONCURRENT_THREADS);

              for (int i = 0; i < NUMBER_OF_TASKS; i++) {

                     executor.submit(new SingleWorker(i));

              }

             

              executor.shutdown();

       }

Solution 2: Summary

When you need to for example summarise output of all threads, and do something with them I usually use List of Future 

       public void start() {

              ExecutorService executor = Executors

                           .newFixedThreadPool(CONCURRENT_THREADS);

             

              //list will kept information about threads status

              List<Future<Long>> list = new ArrayList<Future<Long>>();

             

              for (int i = 0; i < NUMBER_OF_TASKS; i++) {

                     Callable<Long> worker = new SingleWorker(i);

                     Future<Long> submit = executor.submit(worker);

                     list.add(submit);

              }

             

              // now retrieve the result

              for (Future<Long> future : list) {

                     try {

                           //get() is waiting for each thread to finish

                           future.get();

                     } catch (InterruptedException e) {

                           e.printStackTrace();

                     } catch (ExecutionException e) {

                           e.printStackTrace();

                     }

              }

              executor.shutdown();

              // at this point all threads are finish

              // add summary calculations

       }

Note: This is 2010 solution with java 1.6.