Adding content from a database

Question

Hi there, I'm looking for a way to add content to a JComboBox from a database. I have the code to connect the database to my application working fine but am struggling to find the appropriate way to make my JComboBox display data from my database. I'll leave all the code I have at present...
import java.sql.*;
import java.io.IOException;
import java.io.*;
import java.util.Properties;
public class ConnectDB {
     public static void init(String fileName)
     throws  IOException, ClassNotFoundException
          Properties props = new Properties();
          FileInputStream in = new FileInputStream(fileName);
          props.load(in);
          String driver = props.getProperty("jdbc.driver");
          url = props.getProperty("jdbc.url");
          username = props.getProperty("jdbc.username");
          password = props.getProperty("jdbc.password");
          Class.forName(driver);  
     public static Connection getConnection() throws SQLException
          return DriverManager.getConnection(url,username,password);
     private static String url;
     private static String username;
     private static String password;
}     (I obviously have a text file in my folder with my connection details)
Then I'm trying to build a GUI in netbeans that will retrieve and update my database so I have something like this...
    private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {                                        
        jComboBox1.addItem("Please Click Button");
        try{
        ConnectDB myDB = new ConnectDB();
        myDB.init("DBoracle.txt");
        Connection conn = null;
        conn = myDB.getConnection();
        String query = "select * from Employee";
        Statement stmt = null;
        stmt = conn.createStatement();
        ResultSet rs = stmt.executeQuery(query);
        rs.next();
        String s = rs.getString(2);
        //Return the second entry from my database and add it to my JComboBox
        // in theory i'll be adding a loop later to add all the entries to my JComboBox
        jComboBox.setItem(s);
        catch(Exception e){}
    }                                     

Answer 1

Thanks cotton for at least trying to point out my errors, I am only too aware of my lack of experience in doing this sort of thing hence why I'm posting here I'm a student trying to learn about these things and at the moment am admittingly struggling with it. I have read and followed the JDBC tutorial, infact that's where I started with this but it is at best limited and could maybe do with some more sample code on expanding the idea. It does however point to the fact that it is kinda limited in how it returns data:
The ResultSet.getXXX methods are the only way to retrieve data from a ResultSet object, which means that you have to make a method call for each column of a row. It is unlikely that this is the cause of a performance problem, however, because it is difficult to see how a column could be fetched without at least the cost of a function call in any scenario. We welcome input from developers on this issue.
Perhaps some of the developers on here could help solve this issue...
I know my code is a bit messy but it's the trial and error approach I use, cumbersome I know but it's all I know with my limited knowledge. Probably not the best for posting on here but this is my near complete code. The extra textfield will be used to return data from a trigger which tested ok too. So my problem is I want to make textfield1 a combobox that returns all my primary keys from my table and then I could click on one and all my textfields would reflect my choice. e I'm guessing I'd be using an actionListener approach? I don't need the actual code for it I'm quite happy to plough on and try and figure it out for myself cos it's how I'll learn just want a suggestion on how I would approach it..
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;
public class NewJFrame extends javax.swing.JFrame {
    /** Creates new form NewJFrame */
    public NewJFrame() {
        initComponents();
    /** 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.
   //Removed this code cos post too big!
    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                        
        try{
        ConnectDB myDB = new ConnectDB();
        myDB.init("DBoracle.txt");
        Connection conn = null;      
        conn = myDB.getConnection();
        String query = "select * from SYSTEM.monitoringLab";
     Statement stmt = null;
        stmt = conn.createStatement();
        ResultSet rs = stmt.executeQuery(query);
        //rs.next();
        // this was being used earlier to test that I was getting my results set
        String s = rs.getString(1);
        String t = rs.getString(2);
        String u = rs.getString(3);
        String v = rs.getString(4);
        String w = rs.getString(5);
        String x = rs.getString(6);
        jTextField1.setText(s);
        jTextField2.setText(t);
        jTextField3.setText(u);
        jTextField4.setText(v);
        jTextField5.setText(w);
        jTextField6.setText(x);
        conn.close();
        stmt.close();
        catch(Exception e){
        System.err.println("Got an exception! ");
        System.err.println(e.getMessage());
    private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {
        jTextField1.setText(null);
        jTextField2.setText(null);
        jTextField3.setText(null);
        jTextField4.setText(null);
        jTextField5.setText(null);
        jTextField6.setText(null);
    private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) {
        try{
        ConnectDB myDB = new ConnectDB();
        myDB.init("DBoracle.txt");
        Connection conn = null;
        conn = myDB.getConnection();
        Statement stmt = null;
        stmt = conn.createStatement();
        stmt.executeUpdate("INSERT INTO SYSTEM.monitoringLab values ("
                + jTextField1.getText() + "," + jTextField2.getText() + ","
                + jTextField3.getText() + "," + jTextField4.getText() + ","
                + jTextField5.getText() + "," + jTextField6.getText() + ")");
        conn.close();
        stmt.close();
        catch(Exception e){
        System.err.println("Got an exception! ");
        System.err.println(e.getMessage());
    * @param args the command line arguments
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new NewJFrame().setVisible(true);
    // Variables declaration - do not modify
    private javax.swing.JButton jButton1;
    private javax.swing.JButton jButton2;
    private javax.swing.JButton jButton3;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JLabel jLabel3;
    private javax.swing.JLabel jLabel4;
    private javax.swing.JLabel jLabel5;
    private javax.swing.JLabel jLabel6;
    private javax.swing.JLabel jLabel7;
    private javax.swing.JLabel jLabel8;
    private javax.swing.JTextField jTextField1;
    private javax.swing.JTextField jTextField2;
    private javax.swing.JTextField jTextField3;
    private javax.swing.JTextField jTextField4;
    private javax.swing.JTextField jTextField5;
    private javax.swing.JTextField jTextField6;
    private javax.swing.JTextField jTextField7;
    // End of variables declaration
}Edited by: jojololo on Dec 11, 2009 4:44 AM