How to display contents of JList or drop down list?

import java.awt.BorderLayout;
import java.awt.Image;
import java.awt.GridLayout;
import java.awt.Panel;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
 
import javax.swing.DefaultListModel;
import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JList;
import javax.swing.JRadioButton;
import javax.swing.JScrollPane;
import javax.swing.ListModel;
import javax.swing.UIManager;
import javax.swing.SwingConstants;

import java.io.*;
import java.sql.*;
import java.net.*;
import java.util.ArrayList;
 
public class sendInterface  /*implements ActionListener*/{
JFrame frame = new JFrame();
ArrayList list = new ArrayList();
Object[] arrayObject=list.toArray();
 
private Panel topPanel;
private Panel sendMessagePanel;
private Panel sendFilePanel;
private JLabel senderID;
private JLabel receiverID;
private JLabel senderDisplay;
private DefaultListModel model = new DefaultListModel();
//private DefaultListModel receiverListModel = new DefaultListModel();
private JList receiverID_lst = new JList(arrayObject);
private JRadioButton sendType;

public String userName;
public String user;
public String receiver;
int i=0;
Connection con;
 
    public sendInterface(String user) {
    userName = user;
    }
    
    public void setUserName(String user)
    {
    this.userName = user;
    System.out.println( "\tuser=" + userName);
    
    }
    
    public String getUserName()
    {
    return this.userName;
    }
    
    public void setListName()
    {
   try{
       Class.forName("com.mysql.jdbc.Driver");
String url = "jdbc:mysql://localhost:3306/thesis";
con = DriverManager.getConnection(url, "root", "");
Statement stmt = con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_READ_ONLY);
ResultSet rs = stmt.executeQuery("select * from user where User_ID!= '" + getUserName() + "'");

System.out.println("Display all results:");
while(rs.next()){
        String User_id = rs.getString("User_ID");
        System.out.println("\tuser_id= " + User_id );
            model.addElement(rs.getString("User_ID"));
        list.add( rs );

}//end while loop

} 
    
    catch(Exception ex)
       {
            ex.printStackTrace();
       }
   finally
       {
           if (con != null)
           {
               try
               {
                   con.close ();
                   System.out.println ("Database connection terminated");
               }
               catch (Exception e) { /* ignore close errors */ }
           }
       }
 
    }
    
    public void myInterface(){
    try
 {
  JFrame.setDefaultLookAndFeelDecorated( true );
    } 
catch (Exception e) 
 {
      System.err.println( "Look and feel not set." );
    }
    System.out.println("\tSender= " + getUserName() );
    frame.setTitle( "Send Interface" );
     frame.setLayout( new GridLayout( 2 , 1 ) );
//    topPanel.setLayout( new GridLayout( 2 , 1 ) );
    senderID = new JLabel( "Sender:", SwingConstants.LEFT );
    senderDisplay = new JLabel( getUserName(), SwingConstants.LEFT );
    receiverID = new JLabel( "Receiver:", SwingConstants.LEFT);
    receiverID_lst.setListData(arrayObject);
receiverID_lst.setFocusable(false);
//    receiverID_lst = new JList( ListName );
receiver=(String) receiverID_lst.getSelectedValue();
 
frame.add(senderID);
    frame.add(senderDisplay);
    frame.add(receiverID);
    frame.add(receiverID_lst);
//    frame.add(new JScrollPane(receiverID_lst), BorderLayout.CENTER);
 
    
    frame.setLocation(200, 200);
    frame.setSize(250, 90);
    frame.setVisible(true);
    }
 
}

i try it,however fail to display the contents.thank and appreciate your help and advise

I think with the contents of that posting, it would sit better on our Swing forum.

Moving.

looks like you may need a refresher course on how things work.

ArrayList list = new ArrayList();
Object[] arrayObject=list.toArray();
private JList receiverID_lst = new JList(arrayObject);

here, arrayObject is empty, ergo, receiverID_lst is also empty.

private DefaultListModel model = new DefaultListModel();
and, later
model.addElement(rs.getString("User_ID"));
all well and good, but means nothing('ether code'), model never being set.

ResultSet rs = stmt.executeQuery....
while(rs.next()){
...
list.add( rs );
...
}
strange bit of code, that lot

receiverID_lst.setListData(arrayObject);
well, arrayObject is still empty (there is no auto-recalculation)

disclaimer: comments from perusal of code only

thank your reply,someone advise me study "Collection Framework".study now.

Start here.