volatile可见性问题

Question

//这个线程可以退出的原因是什么
public class Test {
    public static boolean flag = true;
    public static volatile boolean stop = false;
    public static void main(String[] args) throws InterruptedException {

        Runnable runnable = () -> {
            while (flag != stop){

            }
            System.out.println("结束");
        };
        new Thread(runnable).start();
        Thread.sleep(2000);
        flag = false;
    }
}

Answer 1

这不就定义一个 Runnable 接口嘛， 哪里来的线程啊，Thread 呢