多线程篇七：通过Callable和Future获取线程池中单个务完成后的结果

ExecutorService threadPools=Executors.newSingleThreadExecutor();
        Future<String> future=threadPools.submit(new Callable<String>() {
            @Override
            public String call() throws Exception {
                Thread.sleep(2000);//模拟任务处理2S
                return "hello";
            }
            
        });
        System.out.println("等待结果。。。。。");
        try {
            System.out.println("获取到结果："+future.get());//2S之后任务完成后获取到结果
        } catch (Exception e) {
            e.printStackTrace();
        }

ExecutorService threadPools2=Executors.newFixedThreadPool(10);
        CompletionService<Integer> completetionService=new ExecutorCompletionService<Integer>(threadPools2);
        //提交10个任务
        for(int i=1;i<=10;i++){
            final int seq=i;
            completetionService.submit(new Callable<Integer>(){
                @Override
                public Integer call() throws Exception {
                    Thread.sleep(new Random().nextInt(5000));
                    return seq;
                }
                
            });
        }
        
        for(int i=1;i<=10;i++){
              Future<Integer> futures;
            try {
                futures = completetionService.take();
                System.out.println("拿到任务结果："+futures.get());//在任务完成后拿到结果，哪个任务先完成，则先拿到结果
            } catch (Exception e) {
                e.printStackTrace();
            }
        }