一个线程问题 求解

class Ck
{
    private char[] rl = new char[8];
    private int wp = 0;
   
    public synchronized void shengchan(char aa)
    {
        while (wp == rl.length)
        {
            try
            {
                this.wait();
            }
            catch (Exception e){}
        }
        this.notify(); //叫醒另一个线程。是在当前线程处于就绪状态的前提下
        
        rl[wp] = aa;    ++wp;
        
        System.out.println("生产线程正在生产第"+wp+"个产品，该产品是:"+aa);
    }
   
    public synchronized void xiaofei()
    {
        char aa;
        
        while (wp == 0)
        {
            try
            {
                this.wait();
            }
            catch (Exception e){}
        }
        this.notify();
        aa = rl[wp-1];
        
        System.out.println("消费线程正在消费第"+wp+"个产品，该产品是:"+aa);
        
        --wp;        
    }   
}

class Sc implements Runnable
{
    private Ck xc = null;
   
    public Sc(Ck xc)
    {
        this.xc = xc;
    }
   
    public void run()
    {
        char aa;
        
        for (int i=0; i<26; i++)
        {
            aa = (char)('A'+i);
            xc.shengchan(aa);
        }
    }
}

class Xf implements Runnable
{
    private Ck xc = null;
   
    public Xf(Ck xc)
    {
        this.xc = xc;
    }
   
    public void run()
    {
        for (int i=0; i<26; i++)
        {
            xc.xiaofei();
        }
    }
}

public class L6_12
{
    public static void main(String[] args)
    {
        Ck ck = new Ck();
        Sc sc = new Sc(ck);
        Xf xf = new Xf(ck);
        Thread xc1 = new Thread(sc);
        xc1.start();
               
        Thread xc2 = new Thread(xf);
        xc2.start();
    }
}