Opening a new Frame from an actionPerformed

[Dean_Grobler]

Hi there,

Consider the following code, this is a little 'snipet' from one of my classes:

private void jMenu1ActionPerformed(java.awt.event.ActionEvent evt) {                                       
    NewContact n = new NewContact();
}

The method is expected to open a new Frame, where the class of the new Frame is
called "NewContact". I've recently migrated to Netbeans 6.9.1 So sorry for all the
lengthy comments. I've also used the GUI builder Netbeans offers so that might
make the code rather lengthy also.. Anyways, here's the code for the Frame that
I am trying to invoke/show/pop-up/whatever:

/**
 *
 * @author Dean
 */
public class NewContact extends javax.swing.JFrame {

    /** Creates new form NewContact */
    public NewContact() {
        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() {

        jLabel1 = new javax.swing.JLabel();
        jTextField1 = new javax.swing.JTextField();
        jLabel2 = new javax.swing.JLabel();
        jTextField2 = new javax.swing.JTextField();
        jLabel3 = new javax.swing.JLabel();
        jTextField3 = new javax.swing.JTextField();
        jLabel4 = new javax.swing.JLabel();
        jTextField4 = new javax.swing.JTextField();
        jLabel5 = new javax.swing.JLabel();
        jTextField5 = new javax.swing.JTextField();
        jLabel6 = new javax.swing.JLabel();
        jTextField6 = new javax.swing.JTextField();
        jButton1 = new javax.swing.JButton();
        jButton2 = new javax.swing.JButton();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        setTitle("New Contact");

        jLabel1.setText("Name");

        jLabel2.setText("Surname");

        jLabel3.setText("Mobile");

        jLabel4.setText("Home");

        jLabel5.setText("Work");

        jLabel6.setText("Email");

        jButton1.setText("Save");

        jButton2.setText("Cancel");

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(layout.createSequentialGroup()
                        .addComponent(jLabel1)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 36, Short.MAX_VALUE)
                        .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, 137, javax.swing.GroupLayout.PREFERRED_SIZE))
                    .addGroup(layout.createSequentialGroup()
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addComponent(jLabel2)
                            .addComponent(jLabel3)
                            .addComponent(jLabel4)
                            .addComponent(jLabel5)
                            .addComponent(jLabel6))
                        .addGap(18, 18, 18)
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addComponent(jTextField6, javax.swing.GroupLayout.DEFAULT_SIZE, 140, Short.MAX_VALUE)
                            .addComponent(jTextField5, javax.swing.GroupLayout.DEFAULT_SIZE, 140, Short.MAX_VALUE)
                            .addComponent(jTextField4, javax.swing.GroupLayout.DEFAULT_SIZE, 140, Short.MAX_VALUE)
                            .addComponent(jTextField3, javax.swing.GroupLayout.DEFAULT_SIZE, 140, Short.MAX_VALUE)
                            .addComponent(jTextField2, javax.swing.GroupLayout.DEFAULT_SIZE, 140, Short.MAX_VALUE)))
                    .addGroup(layout.createSequentialGroup()
                        .addComponent(jButton1, javax.swing.GroupLayout.PREFERRED_SIZE, 88, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addGap(18, 18, 18)
                        .addComponent(jButton2, javax.swing.GroupLayout.PREFERRED_SIZE, 91, javax.swing.GroupLayout.PREFERRED_SIZE)))
                .addContainerGap())
        );

        layout.linkSize(javax.swing.SwingConstants.HORIZONTAL, new java.awt.Component[] {jButton1, jButton2});

        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel1)
                    .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel2)
                    .addComponent(jTextField2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel3)
                    .addComponent(jTextField3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel4)
                    .addComponent(jTextField4, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel5)
                    .addComponent(jTextField5, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel6)
                    .addComponent(jTextField6, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGap(18, 18, 18)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jButton1)
                    .addComponent(jButton2))
                .addContainerGap(22, 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 NewContact().setVisible(true);
            }
        });
    }

    // Variables declaration - do not modify                     
    private javax.swing.JButton jButton1;
    private javax.swing.JButton jButton2;
    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.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;
    // End of variables declaration                   

}

When I click the button with the actionListener that invokes the actionPerformed (shown above), nothing happens..

Thanks for taking a look at this, probably sucked having to read all that..
Any help would be appreciated!

[JamesCherrill]

Following normal conventions, the constructor for the new window does everything except make it visible.
Where you have
NewContact n = new NewContact();
you need to follow that with a
n.setVisible(true);

[Dean_Grobler]

Since I'm not at a PC with the JDK available is this all I have to do to make my code run? Also, since I'm new to Netbeans. Both of these classes have a main method in it, is that normal? I thought that only one class in your package can have the main method that would set the ball running for the entire program?

[JamesCherrill]

I can't say that you have no other problems in your code ;-) but the setVisible thing is pretty standard.

You are right, one class in your package can have the main method that would set the ball running for the entire program. But that doesn't mean that you can't have multiple mains in multiple classes, as long as you pick one of them to be the one that's invoked when you execute the program (by picking the class that you execute).

The main in NewContact is an example of another good standard practice. It is a minimal piece of code to test and/or demonstrate what that particular class does. In this case, because it's a window, it creates one and makes it visible. This is a really good idea because you can check out that class's code before trying to integrate it into the rest of the system. Also, if you change it later, you can check out your changes without running the whole app.

[Dean_Grobler]

Ahh! I see, well that's pretty awesome then. I will make start doing that then, having a main() in more than just one class clearly has it's advantages. Otherwise thanks alot for the help :-)

[JamesCherrill]

It's not just for GUI either - it's brilliant for classes like Employee or whatever - the main can create one or two, call the setters, print the results of the getters etc. I do this for almost every such class I write.