how to retrieve data into combo from database in java applet?

hi,. i have written applet codes for linking two frames and database connectivity but the problem is, the database is not retrieving data into the combo..please somebody help me for the right set of codes.i have attached the codes.

//First page
import java.awt.*;
import java.sql.SQLException;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
class gwf extends Frame implements ActionListener
{   public Label l1,l2,l3;
    public TextField tf1,tf2,tf3;
    public JComboBox c1,c2;
    public Button b1,b2;
    public Panel p1,p2;
    String s1;
    gwf(){
        setLayout(new GridLayout(5,1));
        setTitle("FIRST PAGE");
        l1 = new Label("Choose Department");
        c1 = new JComboBox();
        c1.addItem("--select--");
        c1.addItem("Science");
        c1.addItem("Fashion");
        c1.addItem("IT Corporate");
        c1.addItem("Finance");
        c1.addItem("Sociology");
        p1 = new Panel();
        p2 = new Panel();
        b1 = new Button("SUBMIT");
        p1.add(l1);
        p1.add(c1);
        p2.add(b1);
        add(p1, "Center");
        add(p2, "South");
        b1.addActionListener(this);
        setSize(500, 500);
        setVisible(true);}
     public void actionPerformed(ActionEvent e) {
    gwf1 g = new gwf1(s1);
    dispose();}
public static void main(String[] args) throws SQLException {
    gwf g = new gwf();
    }}

//Second page import javax.swing.*; import java.awt.*; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.Statement; class gwf1 extends Frame implements ActionListener { private static final String String =null; Label l1; TextField t1; JComboBox c1,c2; Panel p1,p2; Button b1; String s1, s2; Statement st; ResultSet rs=null; Connection con;

public void init() { try{ Class.forName("org.postgresql.Driver"); con = DriverManager.getConnection("jdbc:postgresql://localhost:5432/departments","postgres", "postgres"); Statement st= con.createStatement(); ResultSet rs=st.executeQuery("SELECT rolename from role WHERE deptid=1234"); while(rs.next()){ c1.addItem(rs.getInt("role_name")); }} catch(Exception e) { e.printStackTrace(); } } public gwf1(String s1) { this.s1 = s1; setLayout(new GridLayout(5, 1)); setTitle("Second Page"); l1 = new Label("Enter Role"); c1 = new JComboBox(); c1.addItem("--select--"); b1 = new Button("SUBMIT"); p1 = new Panel(); p2 = new Panel(); p1.add(l1); p1.add(c1); p2.add(b1); add(p1, "Center"); add(p2, "South"); b1.addActionListener(this); setSize(400, 500); setVisible(true); } public void actionPerformed(ActionEvent e1) { JOptionPane.showMessageDialog(this, "The generated Id is:"); dispose(); }}

View Answers

March 10, 2011 at 11:18 AM

import java.sql.*;
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
class  JComboBoxExample{
    public static void main(String[] args) 
    {
        JFrame f=new JFrame();
        f.setLayout(null);
        JLabel lab=new JLabel("Course Items:");
        final JComboBox combo=new JComboBox();
        combo.addItem("--Select--");
        try{
        Class.forName("com.mysql.jdbc.Driver");
           Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/test", "root", "root");
           Statement st=con.createStatement();
           ResultSet rs=st.executeQuery("select * from student");
           while(rs.next()){
           combo.addItem(rs.getInt("id"));
           }
        }
        catch(Exception e){}
        JButton b=new JButton("Get");
        lab.setBounds(20,20,100,20);
        combo.setBounds(120,20,150,20);
        b.setBounds(120,50,80,20);
        b.addActionListener(new ActionListener(){
        public void actionPerformed(ActionEvent e){
        String value = combo.getSelectedItem().toString();
        JOptionPane.showMessageDialog(null,"You have selected '"+value+"' from ComboBox");
         }
        });
        f.add(lab);
        f.add(combo);
        f.add(b);
        f.setVisible(true);
        f.setSize(300,120);
    }
}