public static void main(String[] args) {

        CompletableFuture<Void> f1 = CompletableFuture.runAsync(() -> {

            try {

                Thread.sleep(2000);

            } catch (InterruptedException e) {

                e.printStackTrace();

            }

            System.out.println("第一个异步任务");

        });

        CompletableFuture<Void> f2 = CompletableFuture.runAsync(() -> {

            try {

                Thread.sleep(2000);

            } catch (InterruptedException e) {

                e.printStackTrace();

            }

            System.out.println("第二个异步任务");

        });

        CompletableFuture.allOf(f1,f2).join();

        System.out.println("CompletableFuture Test runAsync");

    }