使用 rpc 的 Java 程序有错误

Question

使用 rpc 的 Java 程序出现错误。第一个是服务器，第二个是客户端。 这个java（客户端和服务器）程序有什么错误？ 错误窗口在 RPCServer.java 第 34 行和第 86 行显示错误。 检查错误窗口是否相同。（错误最后在代码窗口中） 检查了 Ecllipse oxygen2。请帮助解决这个问题。

//SERVER:-This is the server program (RPCServer.java)//
package demo2;

import java.util.*;
import java.net.*;
class RPCServer
{
    DatagramSocket ds;
    DatagramPacket dp;
    String str,methodName,result;
    int val1,val2;
    RPCServer()
    {
        try
        {
            ds= new DatagramSocket(1200);
            byte b[]=new byte[4096];
            while(true)
            {
                dp= new DatagramPacket(b,b.length);
                ds.receive(dp);
                str= new String(dp.getData(),0,dp.getLength());
                if(str.equalsIgnoreCase("q"))
                {
                    System.exit(1);
                }
                else
                {
                    StringTokenizer st=new StringTokenizer(str,"");
                    int i=0;
                    while(st.hasMoreTokens())
                    {
                        String token=st.nextToken();
                        methodName=token;
                        val1= Integer.parseInt(st.nextToken());
                        val2= Integer.parseInt(st.nextToken());
                    }
                }
                System.out.println(str);
                InetAddress ia=InetAddress.getLocalHost();
                if(methodName.equalsIgnoreCase("add"))
                {
                     result="" + add(val1,val2);
                }
                else if(methodName.equalsIgnoreCase("sub")) 
                { 
                    result= "" + sub(val1,val2);
                } 
                else if(methodName.equalsIgnoreCase("mul")) 
                { 
                    result= "" + mul(val1,val2);
                }
                else if(methodName.equalsIgnoreCase("div"))
                {
                    result= "" + div(val1,val2); 
                }
                byte bl[]=result.getBytes(); 
                DatagramSocket ds1 = new DatagramSocket(); 
                DatagramPacket dp1 = new 
                DatagramPacket(bl,bl.length,InetAddress.getLocalHost(),1300)
                ;
                System.out.println("result : "+result+"\n"); 
                ds1.send(dp1);
            }
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
    }
    public int add(int val1, int val2)
    {
        return val1+val2;
    }
    public int sub(int val3,int val4)
    {
        return val3-val4;
    }
    public int mul(int val3,int val4)
    {
        return val3*val4;
    }
    public int div(int val3,int val4)
    {
        return val3/val4;
    }
    public static void main(String[] args) 
    { 
        new RPCServer();
    }
}

//CLIENT:This is the client program(RPCClient.java)//

package demo2;

import java.io. *; 
import java.net. *; 
class RPCClient 
{ 
    RPCClient() 
    {
        try
        {
            InetAddress ia = InetAddress.getLocalHost(); 
            DatagramSocket ds = new DatagramSocket(); 
            DatagramSocket ds1 = new DatagramSocket(1300);
            System.out.println("\nRPC Client\n");
            System.out.println("Enter method name and parameter like add 3 
            4\n");
            while(true)
            {
                BufferedReader br= new BufferedReader(new 
                InputStreamReader(System.in));
                String str=br.readLine();
                byte b[]=str.getBytes();
                DatagramPacket dp=new DatagramPacket(b,b.length,ia,1200);
                ds.send(dp);
                dp=new DatagramPacket(b,b.length);
                ds1.receive(dp);
                String s=new String(dp.getData(),0,dp.getLength());
                System.out.println("\nResult= "+ s + "\n");
            }
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
    }
    public static void main(String[] args)
    {
        new RPCClient();
    }
}


Error: 
java.util.NoSuchElementException
at java.util.StringTokenizer.nextToken(Unknown Source)
at demo2.RPCServer.<init>(RPCServer.java:34)
at demo2.RPCServer.main(RPCServer.java:86)

Answer 1

                while(st.hasMoreTokens())
                {
                    String token=st.nextToken(" ");
                    methodName=token;
                    val1= Integer.parseInt(st.nextToken(" "));
                    val2= Integer.parseInt(st.nextToken(" "));
                }