jComboBox with database

Hello friends,

I have created three JComboBoxes. first two of them get list from string. However I select these two comboboxes, the third combobox automatically retrieve data of a particular column from my database. But in my code its only get data from first item which automatically seleted by setmodel method. Here I paste the code . Please suggest where I stucked!

/* * To change this template, choose Tools | Templates * and open the template in the editor. */

/* * frame1.java * * Created on Oct 25, 2012, 2:00:29 PM */ package smit.cse; import java.sql.*; /** * * @author MYPC */ public class frame1 extends javax.swing.JFrame {

/** Creates new form frame1 */
public frame1() {
    initComponents();
    String str=(String)jComboBox1.getSelectedItem();

    try{
        Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
        Connection conn = DriverManager.getConnection("jdbc:odbc:feeds");
        Statement st=conn.createStatement();
        ResultSet rs=st.executeQuery("Select * from staffs where dept_name like'"+str+"'");
        while(rs.next()){
            String str1=rs.getString("subject");
            System.out.println(str);
            jComboBox2.addItem(str1);
        }
    }
        catch(Exception e){}


    }

/** This method is called from within the constructor to
 * initialize the form.
 * WARNING: Do NOT modify this code. The content of this method is
 * always regenerated by the Form Editor.
 */
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">                          
private void initComponents() {

    jComboBox1 = new javax.swing.JComboBox();
    jComboBox2 = new javax.swing.JComboBox();

    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

    jComboBox1.setModel(new javax.swing.DefaultComboBoxModel(new String[] { "EEE", "ETC", "CSE" }));

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(layout.createSequentialGroup()
            .addGap(95, 95, 95)
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addComponent(jComboBox2, javax.swing.GroupLayout.PREFERRED_SIZE, 180, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addComponent(jComboBox1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
            .addContainerGap(125, Short.MAX_VALUE))
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(layout.createSequentialGroup()
            .addGap(44, 44, 44)
            .addComponent(jComboBox1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addGap(35, 35, 35)
            .addComponent(jComboBox2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addContainerGap(181, Short.MAX_VALUE))
    );

    pack();
}// </editor-fold>                        

/**
 * @param args the command line arguments
 */
public static void main(String args[]) {
    java.awt.EventQueue.invokeLater(new Runnable() {

        public void run() {
            new frame1().setVisible(true);
        }
    });
}
// Variables declaration - do not modify                     
private javax.swing.JComboBox jComboBox1;
private javax.swing.JComboBox jComboBox2;
// End of variables declaration

}

October 25, 2012 at 6:29 PM

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

/*
 * frame1.java
 *
 * Created on Oct 25, 2012, 2:00:29 PM
 */
package smit.cse;
import java.sql.*;
/**
 *
 * @author MYPC
 */
public class frame1 extends javax.swing.JFrame {

    /** Creates new form frame1 */
    public frame1() {
        initComponents();
        String str=(String)jComboBox1.getSelectedItem();

        try{
            Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
            Connection conn = DriverManager.getConnection("jdbc:odbc:feeds");
            Statement st=conn.createStatement();
            ResultSet rs=st.executeQuery("Select * from staffs where dept_name like'"+str+"'");
            while(rs.next()){
                String str1=rs.getString("subject");
                System.out.println(str);
                jComboBox2.addItem(str1);
            }
        }
            catch(Exception e){}


        }

    /** This method is called from within the constructor to
     * initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is
     * always regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        jComboBox1 = new javax.swing.JComboBox();
        jComboBox2 = new javax.swing.JComboBox();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        jComboBox1.setModel(new javax.swing.DefaultComboBoxModel(new String[] { "EEE", "ETC", "CSE" }));

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(95, 95, 95)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(jComboBox2, javax.swing.GroupLayout.PREFERRED_SIZE, 180, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(jComboBox1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addContainerGap(125, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(44, 44, 44)
                .addComponent(jComboBox1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(35, 35, 35)
                .addComponent(jComboBox2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(181, Short.MAX_VALUE))
        );

        pack();
    }// </editor-fold>                        

    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {

            public void run() {
                new frame1().setVisible(true);
            }
        });
    }
    // Variables declaration - do not modify                     
    private javax.swing.JComboBox jComboBox1;
    private javax.swing.JComboBox jComboBox2;
    // End of variables declaration                   
}