Asynchronous interface

AsyncHandling.java

public interface AsyncHandler {
    <T> Future<T> submit(Callable<T> callable);
}
public class AsyncHandlerImpl implements AsyncHandler {
    private static final int NUM_THREADS = 5;
    /* USING EXECUTORS (java 1.6) */
    private ExecutorService pool = Executors.newFixedThreadPool(NUM_THREADS);
    /* USING EXECUTORS (java 1.7) */
    private final ForkJoinPool pool = new ForkJoinPool(NUM_THREADS);
    @Override
    public <T> Future<T> submit(Callable<T> callable) {
        return pool.submit(callable);
    }
}
//usage
private class DoSomethingWrapper implements Callable {
        public DoSomethingWrapper() {
        }
        @Override
        public Object call() throws Exception {
            return someService.doSomething();
        }
    }
asyncHandler.submit(new DoSomethingWrapper());

Updated with ForkJoin example as well :-).