public class SynchroExample {

   public final AtomicInteger integer = new AtomicInteger(0);

   private ExecutorService service = Executors.newFixedThreadPool(100);

   public void syn() {
      for (int i = 0; i < 1000; i++) {
          service.submit(() -> {
              integer.incrementAndGet();
          });
       }
       service.shutdown();
       System.out.println(integer.get());
   }

   public static void main(String [] args) {
      SynchroExample ex = new SynchroExample();
       ex.syn();
    }
}