Java通过在主循环中判断Boolean来停止线程

Java代码：

package Threads;

/**
 * Created by Frank
 */
public class StopBoolean extends Thread {

    // 确保变化对其它线程可见（主要是主线程要可见）
    protected volatile boolean done = false;

    public void run() {
        while (!done) {
            System.out.println("StopBoolean running");
            try {
                sleep();
            } catch (InterruptedException e) {
                return;
            }
        }
        System.out.println("StopBoolean finished");
    }

    public void shutDown() {
        done = true;
    }

    public static void main(String[] args) throws InterruptedException {
        StopBoolean t1 = new StopBoolean();
        t1.start();
        Thread.sleep( * );
        t1.shutDown();
    }
}