写了一个通讯类 客户端类有个异常问题 请教

客户端先启动   再启动服务器的时候有个异常   不知道怎么解决 
还有就是客户端第一次发信息也有抛出个异常   信息发不出去 
再就是我定义了关毕窗口的时候就关闭通讯类   可是就是关不掉   而是抛出异常   谁帮我看看 帮我改一下啊~!//服务器端
import java.io.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.net.*;
import java.util.*;
public class Server extends JFrame{
    JTextArea txt;
    ServerSocket seSocket=null;
    
    
    public void serve(){
        txt=new JTextArea();
        this.setTitle("学习通讯类");
        this.setLayout(new BorderLayout());
        this.add(txt,BorderLayout.CENTER);
        this.setSize(500,300);
        this.setVisible(true);
        
        try{
            seSocket=new ServerSocket(8000);
            txt.append("服务器启动时间是:"+new Date()+'\n');
          } catch (BindException e) {
                System.out.println("端口使用中....");
                System.out.println("请关掉相关程序并重新运行服务器！");
                System.exit(0);
            } catch (IOException e) {}
            
        try{
            while(true){
            Socket st=seSocket.accept();
            CtThread ct=new CtThread();
            ct.deliveSt(st);
            new Thread(ct).start();
          }
        }catch(IOException e){}
    }
        
    
    
    class CtThread implements Runnable{
        Socket st=null;
        DataInputStream in=null;
        public void deliveSt(Socket st)
        {
            this.st=st;
            try{
                in=new DataInputStream(st.getInputStream());
            }catch(IOException e){}
        }
        
        public void run()
        {
        try{
            BufferedReader br=new BufferedReader(new InputStreamReader(in));
            while(true){
                String Dialog=br.readLine();
                txt.append("从客户端收到信息"+Dialog+'\n');        
              }
            }catch(IOException e){}
        }
    
    }
                public static void main(String args[])
    {
        Server myserver=new Server();
        myserver.serve();
    }
}//客户端类import java.io.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.net.*;
import java.util.*;public class Client extends JFrame implements ActionListener
{
    JTextArea txta;
    JTextField txtf;
    JPanel pl;
    JButton bt;
    DataOutputStream out=null;
    Socket sc=null;
    PrintStream ps;
    Container f=this.getContentPane();
    
    public void client()
    {
        f.setLayout(new BorderLayout());
        txta=new JTextArea();
        f.add(txta,BorderLayout.CENTER);
        txtf=new JTextField(20);
        bt=new JButton("发送");
        pl=new JPanel();
        pl.setLayout(new FlowLayout());
        pl.add(txtf);
        pl.add(bt);
        bt.addActionListener(this);
        txtf.addActionListener(this);
        f.add(pl,BorderLayout.SOUTH);
        setTitle("信息发送端");
        setSize(500,300);
        setVisible(true);
        this.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                disconnect();
                System.exit(0);
            }
        });
        
        try
        {
            Socket sc=new Socket("192.168.0.25",8000);
            out=new DataOutputStream(sc.getOutputStream());
            ps=new PrintStream(out);
        }
        catch(IOException ex)
        {
            txta.append(ex.toString()+'\n');
        }
    
    }
    
    public void actionPerformed(ActionEvent e)
    {
        if(e.getSource()==bt|e.getSource()==txtf)
        {
            String Dialog=txtf.getText();
            try
            {
                ps.println(Dialog);
                txta.append("已经发送对话:"+Dialog+'\n');
                txtf.setText("");
            }
            catch(Exception ex)
            {
                txta.append(ex.toString()+'\n');
            }
        }
    }
    public void disconnect() {
    try {
            out.close();
            sc.close();
          } catch (IOException e) {}
    }
                
    public static void main(String args[])
    {
        Client myclient=new Client();
        myclient.client();
    }
}