线程的第三种创建方式-Callable的使用

线程的第三种创建方式

Callable的使用

public class MyThread implements Callable {
    @Override
    public Integer call() throws Exception {
        System.out.println(Thread.currentThread().getName()+ ":11111111");
        return 1024;
    }
}

public class CallableDemo {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        FutureTask futureTask = new FutureTask<>(new MyThread());

        Thread thread = new Thread(futureTask,"AAA");
        thread.start();

        System.out.println(futureTask.get());
    }
}
AAA:11111111
1024

futureTask.get()建议放在代码的最后面，否则main线程会等待子线程执行完才会执行。

public class CallableDemo {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        FutureTask<Integer> futureTask = new FutureTask<>(new MyThread());

        Thread thread = new Thread(futureTask,"AAA");
        thread.start();

        System.out.println(Thread.currentThread().getName()+"*********");
        int a = 1000;
        while (!futureTask.isDone()){
            System.out.println("未完成");
        }
        System.out.println("------------------------完成");
        int number = futureTask.get();

        System.out.println(a+number);
    }
}

可以加个 while (!futureTask.isDone()){}应用

public class CallableDemo {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        FutureTask<Integer> futureTask = new FutureTask<>(new MyThread());

        new Thread(futureTask,"AAA").start();
        new Thread(futureTask,"BBB").start();

        System.out.println(Thread.currentThread().getName()+"*********");
        int a = 1000;
        int number = futureTask.get();
        System.out.println(a+number);
    }
}
结果：
main*********
AAA:11111111
2024

总结：
两个线程调用同一个任务，只会打印一次，AAA线程或者BBB线程进入。 
除非申请两个不通的任务，就是调用两次
FutureTask<Integer> futureTask2 = new FutureTask<>(new MyThread());
new Thread(futureTask2,"BBB").start();

本文地址：https://blog.csdn.net/qq_41583016/article/details/111991130