新手求教 自学java。。。 书本上说的不详细 基本自己摸索的

程序就一直停在这里了，好像是两个支线线程都在等待



这是代码：

import java.util.*;

class TimeOutput extends Thread
{
    public static volatile boolean stop = false;
    
    public TimeOutput()
    {
        System.out.println("Branch thread begin...");
    }
    
    public void run ()
    {
        System.out.println("Branch thread runnable...");
        while (!stop)
        {
            synchronized (this)
            {
                try
                {
                    System.out.println("Branch thread notify others...");
                    notifyAll();
                    System.out.println("Branch thread waiting...");
                    wait();
                }
                catch (InterruptedException e)
                {
                    e.printStackTrace();
                }
            }
            Calendar temp = Calendar.getInstance();
            System.out.println(temp.get(Calendar.YEAR) + " : " + temp.get(Calendar.MONTH)
                    + " : " + temp.get(Calendar.DAY_OF_MONTH) + "     " + temp.get(Calendar.HOUR_OF_DAY)
                    + " : " + temp.get(Calendar.MINUTE) + " : " + temp.get(Calendar.SECOND));
        }
        System.out.println("Branch thread ended");
    }
}

class PriNumJudge extends Thread
{
    public PriNumJudge()
    {
        System.out.println("Main thread begin...");
    }
    
    public void judgement(int temp)
    {    
        System.out.println("Judge " + temp + " is a prime number or not.");        
        
        boolean flag = true;
        if (temp < 2)
        {
            System.out.println("Judgement input number error.");
        }
        else if ((2 == temp) || (3 == temp))
        {
            System.out.println(temp + " is a prime number.");            
        }
        else
        {
            for (int i = 2; i <= Math.sqrt(temp); i++)
            {
                if (temp % i == 0)
                {
                    flag = false;
                    break;
                }
            }
            if (flag)
            {
                System.out.println(temp + " is a prime number.");
            }
            else
            {
                System.out.println(temp + " isn't a prime number.");
            }
        }
        System.out.println("Judge " + temp + " completed.");
    }
    
    public void run()
    {
        System.out.println("Main thread runable...");
        synchronized (this)
        {
            for (int i = 1; i < 100; i++)        
            {                        
                try
                {
                    System.out.println("Main thread notify others...");
                    notifyAll();
                    System.out.println("Main thread waiting...");
                    wait();
                }
                catch (InterruptedException e)
                {
                    e.printStackTrace();
                }
                this.judgement(i);
            }
            System.out.println("Change loop condition...");
            TimeOutput.stop = true;
        }
        System.out.println("Main thread ended.");
    }
}
public class Test4
{
    public static void main(String[] args)
    {
        System.out.println("Main method begin...");
        PriNumJudge mainThread = new PriNumJudge();
        mainThread.start();
        TimeOutput branchThread = new TimeOutput();
        branchThread.start();
        System.out.println("Main method ended");        
    }
}

这个程序就是 想建立俩线程 然后一个是算是不是质数  另一个显示当前时间
想让他们交替运行 但是 好像我对notify（） wait（）方法应用错误 是理解不够透彻。。
不知道有木有谁稍微讲一下 javadoc 书本也没有得到想要的解答