package com.jysemel.java.future;


import lombok.SneakyThrows;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.*;

public class FutureTaskDemo {
    @SneakyThrows
    public static void main(String[] args) {
        List<FutureTask<Integer>> taskList = new ArrayList<>();
        ExecutorService execute = Executors.newScheduledThreadPool(2);
        for (int i = 0; i < 5; i++) {
            // 传入Callable对象创建FutureTask对象
            FutureTask<Integer> task = new FutureTask<>(new ComputeTask(i, "" + i));
            taskList.add(task);
            // 提交给线程池执行任务，也可以通过exec.invokeAll(taskList)一次性提交所有任务;
            execute.submit(task);
            System.out.println("所有计算任务提交完毕, 主线程接着干其他事情！");
        }
        int result = 0;
        // 从future中取出值来
        for (FutureTask<Integer> future : taskList) {
            int temp = future.get();
            System.out.println("子任务结果=" + temp);
            result = result + temp;
        }
        // 打印求出来的值
        System.out.println("结果合计=" + result);
    }


    static class ComputeTask implements Callable<Integer> {
        private Integer result = 0;
        private String taskName = "";
        ComputeTask(Integer result, String taskName) {
            this.result = result;
            this.taskName = taskName;
            System.out.println("生成子线程计算任务: " + taskName);
        }
        @Override
        public Integer call() throws Exception {
            for (int i = 0; i < 10; i++) {
                result += i;
            }
            Thread.sleep(TimeUnit.SECONDS.toMillis(5));
            System.out.println("子线程计算任务: " + taskName + " 执行完成!");
            return result;
        }

    }
}