多线程之callable接收返回值

实现一个线程有三种方案，分别为继承Thread、实现Runnbale和实现Callable,Callable相对Runnable而言，可以实现对结果的接受，现就callable接受返回值并处理进行简单实践，
实现过程如下：

1. 设计一个线程操作类CallableTest，实现Callable接口。
2. 初始化一个线程池service。
3. 实例化CallableTest。
4. 初始化一个list。
5. 使用线程池调度callabletest任务，并将返回值存储到list中。
6. list遍历。

CallableTest

package com.callable;

import java.util.Date;
import java.util.concurrent.Callable;

/**
 * @author 席鹏
 * @date 2021-07-17 14:19
 * @description:
 */
public class CallableTest implements Callable {
    @Override
    public Object call() throws Exception {
        Thread.sleep(10);
        System.out.println("当前线程:"+Thread.currentThread().getName());
        return new Date();
    }
}

测试类

package com.callable;

import org.junit.Test;

import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

/**
 * @author 席鹏
 * @date 2021-07-17 14:20
 * @description:
 */
public class TestRun {
    @Test
    public void testRun() throws ExecutionException, InterruptedException {
        CallableTest callableTest = new CallableTest();
        ExecutorService service = Executors.newFixedThreadPool(3);
        ArrayList<Future<Date>> list = new ArrayList<>();
        for (int i = 0; i < 20; i++) {
            list.add(service.submit(callableTest));
        }

        for (Future<Date> dateFuture : list) {
            System.out.println(dateFuture.get());
        }

    }
}

运行结果

当前线程:pool-1-thread-3
当前线程:pool-1-thread-1
当前线程:pool-1-thread-2
Sat Jul 17 14:44:38 CST 2021
Sat Jul 17 14:44:38 CST 2021
Sat Jul 17 14:44:38 CST 2021
当前线程:pool-1-thread-1
当前线程:pool-1-thread-3
当前线程:pool-1-thread-2
Sat Jul 17 14:44:38 CST 2021
Sat Jul 17 14:44:38 CST 2021
Sat Jul 17 14:44:38 CST 2021
当前线程:pool-1-thread-2
当前线程:pool-1-thread-3
当前线程:pool-1-thread-1
Sat Jul 17 14:44:38 CST 2021
Sat Jul 17 14:44:38 CST 2021
Sat Jul 17 14:44:38 CST 2021
当前线程:pool-1-thread-3
当前线程:pool-1-thread-2
当前线程:pool-1-thread-1
Sat Jul 17 14:44:38 CST 2021
Sat Jul 17 14:44:38 CST 2021
Sat Jul 17 14:44:38 CST 2021
当前线程:pool-1-thread-2
当前线程:pool-1-thread-3
当前线程:pool-1-thread-1
Sat Jul 17 14:44:38 CST 2021
Sat Jul 17 14:44:38 CST 2021
Sat Jul 17 14:44:38 CST 2021
当前线程:pool-1-thread-2
当前线程:pool-1-thread-1
当前线程:pool-1-thread-3
Sat Jul 17 14:44:38 CST 2021
Sat Jul 17 14:44:38 CST 2021
Sat Jul 17 14:44:38 CST 2021
当前线程:pool-1-thread-2
当前线程:pool-1-thread-1
Sat Jul 17 14:44:38 CST 2021
Sat Jul 17 14:44:38 CST 2021
Process finished with exit code 0