UDP通信程序，高手给看看错在哪里？

Question

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.net.*;public class tongxun extends JFrame implements ActionListener {
    public  static void main(String args[]){
       tongxun frame=new tongxun();
    }
    JButton command,command2,command3;
    JRadioButton rb[]=new JRadioButton[2];
    JTextArea ta1;
    JTextField tf1,tf2,tf3;
    DatagramSocket socket1;
    String strbuf="";
    mt_server t1;
    mt_client t2;
    public tongxun(){
        super("UDP通信");
        Container c=getContentPane();
        c.setLayout(null); 
        
        JLabel lb=new JLabel("UDP协议通信程序");
        lb.setFont(new Font("宋体",Font.BOLD,16));
        lb.setForeground(Color.black);     
        lb.setSize(200,20);
        lb.setLocation(10,2); 
        c.add(lb);         String str1[]={"服务器","客户端"};
        ButtonGroup bg1=new ButtonGroup();
        for(int i=0;i<2;i++)
         {
           rb[i]=new JRadioButton(str1[i]);
           rb[i].setFont(new Font("宋体",Font.BOLD,16));
           rb[i].setForeground(Color.black);     
           rb[i].setSize(80,20);
           rb[i].setLocation(10+i*80,27); 
           c.add(rb[i]);
           bg1.add(rb[i]);
         }  
        rb[0].setSelected(true);
       
        JLabel lb1=new JLabel("连接主机名称");
        lb1.setFont(new Font("宋体",Font.BOLD,16));
        lb1.setForeground(Color.black);     
        lb1.setSize(120,25);
        lb1.setLocation(10,55); 
        c.add(lb1);         tf1=new JTextField("mike");
        tf1.setForeground(Color.black);     
        tf1.setSize(250,25);
        tf1.setLocation(120,55); 
        c.add(tf1); 
       
        command=new JButton("连接");
        command.setFont(new Font("宋体",Font.BOLD,16));
        command.setSize(110,20);
        command.setLocation(380,55);
        command.addActionListener(this);
        c.add(command);        JLabel lb2=new JLabel("接收到的信息");
        lb2.setFont(new Font("宋体",Font.BOLD,16));
        lb2.setForeground(Color.black);     
        lb2.setSize(120,20);
        lb2.setLocation(10,85); 
        c.add(lb2); 
     
        ta1=new JTextArea("好郁闷");
        ta1.setForeground(Color.black);     
        ta1.setSize(250,200);
        ta1.setLocation(120,85); 
        c.add(ta1);         JLabel lb3=new JLabel("发送信息");
        lb3.setFont(new Font("宋体",Font.BOLD,16));
        lb3.setForeground(Color.red);     
        lb3.setSize(110,25);
        lb3.setLocation(10,300); 
        c.add(lb3);           tf2=new JTextField("郁闷");
        tf2.setForeground(Color.red);     
        tf2.setSize(250,25);
        tf2.setLocation(120,300); 
        c.add(tf2);         command2=new JButton("发送信息");
        command2.setFont(new Font("宋体",Font.BOLD,16));
        command2.setSize(110,25);
        command2.setLocation(380,300);
        command2.addActionListener(this);
        c.add(command2);        JLabel lb4=new JLabel("连接状态");
        lb4.setFont(new Font("宋体",Font.BOLD,16));
        lb4.setForeground(Color.black);     
        lb4.setSize(100,25);
        lb4.setLocation(300,27); 
        c.add(lb4);           tf3=new JTextField("离线");
        tf3.setForeground(Color.black);     
        tf3.setSize(100,25);
        tf3.setLocation(380,25); 
        c.add(tf3);         command3=new JButton("结束连接");
        command3.setFont(new Font("宋体",Font.BOLD,16));
        command3.setSize(110,20);
        command3.setLocation(380,85);
        command3.addActionListener(this);
        c.add(command3);
        
        t1=new mt_server();
        t2=new mt_client();
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(500,400);
        setVisible(true);
        } 
        

Answer 1

//事件处理
               public void actionPerformed(ActionEvent e){
                   if(e.getSource()==command){//连接
                       try{
                           if(rb[0].isSelected()==true){
                               tf2.setText("");
                               t1.start();
                               }
                           else{
                                tf2.setText("");
                                t2.start();
                               }
                         }catch(Exception e2){tf3.setText("发生错误");}  
                    }
                  
                  if(e.getSource()==command2){ //发送
                       strbuf=tf2.getText();
                       tf2.setText("");                    
                  }                   if(e.getSource()==command3){//结束连接
                       try{
                           if(rb[0].isSelected()==true){
                                socket1.close();
                                t1.interrupt();
                               }
                           else{
                                t2.interrupt();                                  
                               }
                              tf3.setText("离线");
                              command2.setEnabled(false);
                              command3.setEnabled(false);
                         }catch(Exception e2){tf3.setText("发生错误");}    
                  }
                }
         //服务器线程
               class mt_server extends Thread{
                   public mt_server(){}
                   public void run(){
                       String str1; 
                        
                       try{
                         command.setEnabled(false);
                         socket1=new DatagramSocket(902);
                         tf1.setText(InetAddress.getLocalHost().getHostName());
                         tf3.setText("连接中");
                         command2.setEnabled(true);
                         command3.setEnabled(true);
                         while(true){
                         
                                  //接收
                            
                           byte[] inbuffer=new byte[256];
 
                           DatagramPacket packet1=new DatagramPacket(inbuffer,inbuffer.length);
                           socket1.receive(packet1);
                           str1=new String(packet1.getData());
                           str1=str1.trim();
                         
                           if(str1.length()>0){
                              ta1.append(str1+"\n"); }        
                            
                                 //发送
                           
                            byte[] outbuffer=new byte[str1.length()];
                            str1=strbuf;
                            strbuf="";
                            outbuffer=str1.getBytes();
                            InetAddress address=packet1.getAddress();
                            int port=packet1.getPort();  
                            packet1=new DatagramPacket(outbuffer,outbuffer.length,address,port);
                            socket1.send(packet1);
                         }
                       }catch(IOException e){return;}  
                    }
              }
         //客户端线程
               class mt_client extends Thread{
                   public mt_client(){};
                   public void run(){
                     String str1;
                       DatagramPacket packet1;
                     try{
                         command.setEnabled(false);
                         DatagramSocket socket1=new DatagramSocket();
                         tf3.setText("连接中");
                         command2.setEnabled(true);
                         command3.setEnabled(true);
                         while(true){
                          
                                  //发送
                            str1=strbuf;
                            strbuf="";
                            byte[] outbuffer=new byte[str1.length()];
                            
                         
                            outbuffer=str1.getBytes();
                            InetAddress address=InetAddress.getByName(tf1.getText()); 
                            packet1=new DatagramPacket(outbuffer,outbuffer.length,address,902);
                            socket1.send(packet1);
                                  //接收
                           
                           byte[] inbuffer=new byte[256];
                           packet1=new DatagramPacket(inbuffer,inbuffer.length);
                           socket1.receive(packet1);
                           str1=new String(packet1.getData());
                           str1=str1.trim();
                           if(str1.length()>0){
                              ta1.append(str1+"\n"); }        
                            }
                          
                       }catch(IOException e){}  
                    }
              }
}

Answer 2

小弟刚学JAVA不多久，模仿别人编了个UDP通信程序，可是出了点小问题，不能接收消息并显示出来，有好心人给看看吗？在此谢谢了