Callable

public void test() throws ExecutionException, InterruptedException {
    ExecutorService executorService =Executors.newFixedThreadPool(2);
    long s = System.currentTimeMillis();
    Callable<String> c = new Callable<String>() {
        @Override
        public String call() throws Exception {
            return a ();
        }
    };
    Callable<String> c2 = new Callable<String>() {
        @Override
        public String call() throws Exception {
            return a2 ();
        }
    };
    FutureTask<String> ft = new FutureTask<>(c);
    FutureTask<String> ft2 = new FutureTask<>(c2);
    executorService.submit(ft);
    executorService.submit(ft2);
    System.err.println(ft.get());
    System.err.println(ft2.get());
    long e = System.currentTimeMillis();
    System.err.println(e-s);
}