CompletableFuture3

public class CompletableFuture3 {


    public static void main(String[] args) throws ExecutionException, InterruptedException {
//        testJoin();
         testCompletableException();
    }

    /**
     * completeExceptionally可以使得get方法不会阻塞，如果future没有完成，那调用get方法会抛出异常
     * @throws ExecutionException
     * @throws InterruptedException
     */
    public static  void  testCompletableException() throws ExecutionException, InterruptedException {
        CompletableFuture<String> future = CompletableFuture.supplyAsync(() -> {
            sleep(5);
            System.out.println("=======");
            return "hello";
        });
        sleep(1);
        future.completeExceptionally(new Exception());
        System.out.println(future.get());
    }

    /**
     * 获取结果时，与get的区别是get会抛出检查异常，join不会抛出检查异常
     */
    public static  void  testJoin(){
        CompletableFuture<String> future = CompletableFuture.supplyAsync(() -> {
            sleep(5);
            System.out.println("=======");
            return "hello";
        });
        String result = future.join();
        System.out.println(result);
    }

    private static  void  sleep(int sec){
        try {
            TimeUnit.SECONDS.sleep(sec);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}