FutureTask

FutureTask

RunnableFuture继承了Runnable接口和Future接口，而FutureTask实现了RunnableFuture接口，所以FutureTask既可以作为Runnable被线程执行，又可以作为Future得到Callable的返回值。

FutureTask代码举例

1 测试类-FutureTaskTest02

package com.sqq.future;

import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.FutureTask;

/**
 * @description: Callable+FutureTask获取执行结果
 * 可以看出RunnableFuture继承了Runnable接口和Future接口，而FutureTask实现了RunnableFuture接口。
 * 所以它既可以作为Runnable被线程执行，又可以作为Future得到Callable的返回值。
 * @author: shiqiangqiang
 * @createDate: 2020/6/21
 * @version: 1.0
 */
public class FutureTaskTest02 {
    public static void main(String[] args) {
        test02();
    }

    /**
     * 第一种方式
     */
    private static void test01(){
        ExecutorService executor = Executors.newCachedThreadPool();
        Task task = new Task();
        FutureTask<Integer> futureTask = new FutureTask<>(task);
        executor.submit(futureTask);
        executor.shutdown();
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e1) {
            e1.printStackTrace();
        }

        System.out.println("主线程在执行任务");

        try {
            System.out.println("task运行结果" + futureTask.get());
        } catch (InterruptedException | ExecutionException e) {
            e.printStackTrace();
        }
        System.out.println("所有任务执行完毕");
    }

    /**
     * 第二种方式，注意这种方式和第一种方式效果是类似的，只不过一个使用的是ExecutorService，一个使用的是Thread
     */
    private static void test02(){
        Task task = new Task();
        FutureTask<Integer> futureTask = new FutureTask<>(task);
        Thread thread1 = new Thread(futureTask);
        thread1.start();

        try {
            System.out.println("test02 task运行结果" + futureTask.get());
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (ExecutionException e) {
            e.printStackTrace();
        }

        System.out.println("test02 所有任务执行完毕");
    }

}

2 任务类-Task

package com.sqq.future;

import java.util.concurrent.Callable;

/**
 * @description:
 * @author: shiqiangqiang
 * @createDate: 2020/6/21
 * @version: 1.0
 */
public class Task implements Callable<Integer> {

    @Override
    public Integer call() throws Exception {
        System.out.println("子线程在进行计算");
        Thread.sleep(3000);
        int sum = 0;
        for (int i = 0; i < 100; i++){
            sum += i;
        }
        return sum;
    }
}