java并发编程

一、java线程

1.三种创建线程的方式

Integer sum = futureTask.get(); 会等待其对应的线程执行完 ，即阻塞 再获得结果。

所以我在测试时，出现一个小插曲

@Slf4j
public class ThreeWays {
    //1.自定义MyThread进行继承Thread
    static void test001(){
        Thread thread = new MyThread();
        thread.setName("t1");
        thread.start();
    }
    //2.实现Runnable接口
    static void test002(){
        Thread thread=new Thread(()-> {
            for (int i = 0; i <1000 ; i++) {
                log.info("{}",i);
            }
        });
        thread.setName("t2");
        thread.start();
    }
    //3.实现
    static Integer test003() throws ExecutionException, InterruptedException {

        FutureTask<Integer> futureTask=new FutureTask<>(new Callable<Integer>() {
            @Override
            public Integer call() throws Exception {
                int num=0;
                for (int i = 0; i < 1000000; i++) {
                    num+=i;
                    log.info("{}",i);
                }
                return num;
            }
        });
        Thread thread=new Thread(futureTask);
        thread.start();
        Integer sum = futureTask.get();
        log.info("sum为:{}",sum);
        return sum;
    }
    public static void main(String[] args) throws InterruptedException, ExecutionException {
//        test001();
//        test002();
          test003();
        log.info("123");
    }
}

2. Thread跟Runable的关系

当使用Runable作为参数时 ，即 new Thread( runnable )

把runnable 赋给 target

再运行时，去判断，究竟是否调用 targert.run()

2.linux查看线程信息