Java SE (Java Platform, Standard Edition)

hello
I am trying to make a Chat server, for this i am using JList for the friend list and all users. but when i try to add more than 1 friend , my window hangs. Dont know why. also the double click is not getting enabled in dlist.
my code looks like

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.sql.*;
import java.net.*;
import javax.swing.event.*;
import java.io.*;
import java.util.*;

public class msgwin extends JFrame implements MouseListener,ListSelectionListener
{
  JFrame jf;
  DefaultListModel defau1=new DefaultListModel();
  DefaultListModel defau2=new DefaultListModel();
  JList slist=new JList(defau1);
  JList dlist=new JList(defau2);
  JLabel slabel,dlabel;
  public JButton sub;
  String name;
  BufferedReader reader;
  PrintWriter writer;
  Socket sock;
  public JTextArea msg;
  public JTextArea ja;
  msgwin()
  {
   jf=new JFrame("Grape Chat v1.2 beta");
   //jf.setBounds(40,30,500,400);
   jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
   JFrame.setDefaultLookAndFeelDecorated(true);
   GridBagLayout layout=new GridBagLayout();
   jf.setLayout(layout);
   jf.setResizable(true);
   jf.setSize(450,500);
   slabel=new JLabel("ALL USERS");
   dlabel=new JLabel("MY GANG");
   sub=new JButton("Submit");
    msg=new JTextArea(3,8);
   msg.setEditable(true);
   msg.setLineWrap(true);
   JScrollPane textar=new JScrollPane(msg,ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS,ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS);
   
   try
   {
        Class.forName("oracle.jdbc.driver.OracleDriver");
	Connection con=DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:orcl","SCOTT","iamakhila");
	Statement st=con.createStatement();
	ResultSet rs=st.executeQuery("select firstname from data");
	
	//defau1=new DefaultListModel();
	
	while(rs.next())
	{
	 name=rs.getString("firstname");
	 
	 defau1.addElement(name);
	}
   
 
   
     

   slist.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
   dlist.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
  slist.setSelectedIndex(0);
   slist.addListSelectionListener(this);
   slist.addMouseListener(this);
   slist.setVisibleRowCount(10);
   slist.setFixedCellWidth(22);
   
   st.close();
   con.close();
   
  }catch(Exception e){}
   
  JScrollPane listScrollPane = new JScrollPane(slist);  
   
  
  dlist.setVisibleRowCount(10);
  JScrollPane dscroll=new JScrollPane(dlist);
  
  ja=new JTextArea(4,8);
  JScrollPane textar1=new JScrollPane(ja,ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS,ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS);
   ja.setLineWrap(true);
  ja.setEditable(false);
  jf.add(slabel,new GBC(0,0).setAnchor(GBC.WEST).setInsets(10));
  jf.add(dlabel,new GBC(4,0,1,1).setAnchor(GBC.EAST).setInsets(10));
  jf.add(textar1,new GBC(1,0,2,2).setFill(GBC.BOTH).setWeight(100,100).setInsets(10));
  jf.add(textar,new GBC(1,4,1,1).setFill(GBC.BOTH).setWeight(100,100).setInsets(10));
  jf.add(listScrollPane,new GBC(0,1,1,1).setFill(GBC.BOTH).setWeight(100,100).setInsets(10));
  jf.add(dscroll,new GBC(4,1,1,1).setFill(GBC.BOTH).setWeight(100,100).setInsets(10));
  jf.add(sub,new GBC(1,5,1,1).setInsets(10));
  final JButton del=new JButton("Delete Friend");
  jf.add(del,new GBC(4,2,1,1).setInsets(10));
  
  ActionListener listener=new ActionListener(){
  public void actionPerformed(ActionEvent event)
  {
   //if(event.getSource()==sub)
    
     /*chatclient c1=new chatclient();
	 c1.abc();
	 c1.go();*/
   
   
   if(event.getSource()==del)
   {
      int select=JOptionPane.showConfirmDialog(jf,"Do yo want to remove the selected person from your friends??..","Confirm dialog",JOptionPane.YES_NO_OPTION,
JOptionPane.PLAIN_MESSAGE);
     if(select==JOptionPane.OK_OPTION){
     String str=(String)dlist.getSelectedValue();
	 defau2.removeElement(str);}
	} 
  }
 };
//sub.addActionListener(listener); 
del.addActionListener(listener); 
  jf.setVisible(true);
 }

 public void valueChanged(ListSelectionEvent e)
 {
 }
  public void mouseClicked(MouseEvent e)
  {
   
   if((JList)e.getSource()==slist)
   {//=(JList)e.getSource();
   Object index=slist.getSelectedValue();
   
   if(e.getClickCount()==2)
   {
     int selection=JOptionPane.showConfirmDialog(jf,"Do yo want to add the selected person as your friend??..","Confirm dialog",JOptionPane.YES_NO_OPTION,
JOptionPane.PLAIN_MESSAGE);
     if (selection==JOptionPane.YES_OPTION)
	 {
	  boolean flag=false;
	  String str="";
	  
	  while(str!=null)
	  {
	   int i=0;
	   dlist.setSelectedIndex(i);
	   str=(String)dlist.getSelectedValue();
	   if(index==str)
	   {flag=true;
	   JOptionPane.showConfirmDialog(jf,"Selected person is already your friend!!","Exit",JOptionPane.DEFAULT_OPTION,
JOptionPane.PLAIN_MESSAGE);
         break;
		}}
     if(!flag)
     defau2.addElement((String)index);
	}
  }
  }
  
  if((JList)e.getSource()==dlist)
  {
  
  if(e.getClickCount()==2)
  {
  Object val=dlist.getSelectedValue();
   try
   {
    Class.forName("oracle.jdbc.driver.OracleDriver");
	Connection con=DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:orcl","SCOTT","iamakhila");
	Statement st=con.createStatement();
	ResultSet rs=st.executeQuery("select firstname from data");
	
	//defau1=new DefaultListModel();
	
	while(rs.next())
	{
	 name=rs.getString("firstname");
	 if(name==val)
	 {
	   ma m=new ma();
     }
   
   }
  }catch(Exception xxx)
  {}
  }
  }
  }
 public void mouseEntered(MouseEvent e){}
  public void mouseExited(MouseEvent e){}
  public void mousePressed(MouseEvent e){}
  public void mouseReleased(MouseEvent e){}
  


    
      
  public static void main(String args[])
  {
     msgwin ms=new msgwin();
  }
 }
 
 
 class GBC extends GridBagConstraints
{
 public GBC(int gridx,int gridy)
 {
  this.gridx=gridx;
  this.gridy=gridy;
 }

 public GBC(int gridx,int gridy,int gridwidth,int gridheight)
 {
  this.gridx=gridx;
  this.gridy=gridy;
  this.gridwidth=gridwidth;
  this.gridheight=gridheight;
 }

 public GBC setAnchor(int anchor)
 {
  this.anchor=anchor;
  return this;
 }

 public GBC setFill(int fill)
 {
  this.fill=fill;
  return this;
 } 
 
 public GBC setWeight(double weightx,double weighty)
 {
  this.weightx=weightx;
  this.weighty=weighty;
  return this;
 } 
 
 public GBC setInsets(int top, int left, int bottom, int right) 
 {
  this.insets = new Insets(top, left, bottom, right);
  return this;
 } 

 public GBC setInsets(int distance)
 {
  this.insets=new Insets(distance,distance,distance,distance);
  return this;
 }

 public GBC setIpad(int ipadx,int ipady)
 {
   this.ipadx=ipadx;
   this.ipady=ipady;
   return this;
 } 
}  
    	
	
     
please help me. i am really stuck.i know the problem is in while loop but i am not getting what it to replace with.i have tried all the variations.

thanking in advance