class DelayThread exends Thread { private static int count=0; private int no; private int delay; public DelayThread(){ count++; no=count; } public void run(){ try{ for (int i=0;i<10;i++){ delay=(int)(Math.random()*5000); sleep(delay); System.out.println(“线程”+no+“ 的延迟时间是 ”+delay); } }catch(InterruptedException e){} } } public class MyThread{ public static void main(String args[]){ DelayThread thread1=new DelayThread(); DelayThread thread2=new DelayThread(); thread1.start(); thread2.start(); try{ Thread.sleep(1000);} catch(InterruptedException e){ System.out.println(“线程出错！”); } } } 将上列程序利用Runnable接口改写，并上机检验。

下面是利用Runnable接口改写后的程序：

class DelayRunnable implements Runnable {
    private static int count = 0;
    private int no;
    private int delay;

    public DelayRunnable(){
        count++;
        no = count;
    }

    public void run(){
        try{
            for (int i = 0; i < 10; i++){
                delay = (int)(Math.random()*5000);
                Thread.sleep(delay);
                System.out.println("线程" + no + "的延迟时间是" + delay);
            }
        } catch(InterruptedException e){}
    }
}

public class MyThread {
    public static void main(String[] args){
        DelayRunnable r1 = new DelayRunnable();
        DelayRunnable r2 = new DelayRunnable();
        Thread thread1 = new Thread(r1);
        Thread thread2 = new Thread(r2);
        thread1.start();
        thread2.start();
        try{
            Thread.sleep(1000);
        } catch(InterruptedException e){
            System.out.println("线程出错！");
        }
    }
}

程序会创建两个DelayRunnable对象并各自创建线程，并且每个线程都会执行10次循环，每次循环中会随机生成一个延迟时间并让线程休眠这个时间。在main函数中，程序会让主线程休眠1秒钟，以便让其他两个线程有足够的时间执行完毕。