Question

I am using Netbeans 7.3 Beta 2 GUI builder. Coding a Swing GUI and I am trying to show another GUI once a button has been pressed.

private void loginButtonSceneActionPerformed(java.awt.event.ActionEvent evt) {
    new LoginGUI();
}

Once login button is pressed I want to show the LoginGUI but it does nothing and Netbeans states “New instance ignored”. I’ve added a system.out.println on the button to make sure it works fine and it does.

Here is more or less the full source. Where am I going wrong? I want to replace this GUI with the login GUI.

package com.john.spp.view;
import java.sql.ResultSet;
import java.sql.Statement;

/**
 *
 * @author John
 */
public class LogRegGUI extends javax.swing.JFrame {

/**
 * Creates new form LoginGUI
 */
public LogRegGUI() {
    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.
 */
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
   //GUI BUILDER CODE HERE
}// </editor-fold>

private void loginButtonSceneActionPerformed(java.awt.event.ActionEvent evt) {
    new LoginGUI();
}

private void registerSceneButtonActionPerformed(java.awt.event.ActionEvent evt) {
    // TODO add your handling code here:
}

/**
 * @param args the command line arguments
 */
public static void main(String args[]) {
    /* Set the Nimbus look and feel */
    //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
    /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
     * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
     */
    try {
        for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
            if ("Nimbus".equals(info.getName())) {
                javax.swing.UIManager.setLookAndFeel(info.getClassName());
                break;
            }
        }
    } catch (ClassNotFoundException ex) {
        java.util.logging.Logger.getLogger(LogRegGUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (InstantiationException ex) {
        java.util.logging.Logger.getLogger(LogRegGUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (IllegalAccessException ex) {
        java.util.logging.Logger.getLogger(LogRegGUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (javax.swing.UnsupportedLookAndFeelException ex) {
        java.util.logging.Logger.getLogger(LogRegGUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    }
    //</editor-fold>

    /* Create and display the form */
    java.awt.EventQueue.invokeLater(new Runnable() {
        public void run() {
            new LogRegGUI().setVisible(true);
        }
    });
}
// Variables declaration - do not modify
private javax.swing.JButton dataVaultButton;
private javax.swing.JButton helpButton;
private javax.swing.JEditorPane jEditorPane1;
private javax.swing.JLabel jLabel3;
private javax.swing.JPanel jPanel1;
private javax.swing.JPanel jPanel2;
private javax.swing.JScrollPane jScrollPane1;
private javax.swing.JButton loginButton;
private javax.swing.JButton logoutButton;
private javax.swing.JButton registerButton;
private javax.swing.JButton settingsButton;
// End of variables declaration
}

Thanks.

EDIT:

Fixed it by using this code, but it looks quite bad as it flashes quite quickly and re-draws the new GUI, any ideas on how to stop this?

private void loginButtonSceneActionPerformed(java.awt.event.ActionEvent evt) { 
    LoginGUI itemloader=new LoginGUI();
    itemloader.setVisible(true);
    this.setVisible(false);
} 

Answer 1

There’re several causes why using multiple frames isn’t the best solution for applications. Well, it often leaves a confused user and as you see brings several complications.
As I already suggested at the comments you could let you guide by my other answer yesterday by constructing all your JFrames before you show them. If you then set them visible, there won’t be so much delay as it is now and also you save some memory and CPU time.
Another way may be to just use one single frame and change it’s contents. This answer has really grown to my favorite in referencing 😉
This way there’s also the possibility to construct first and then instantly show what you’ve already build. No delay, no flickering.