Question

I understand the “How to Use Actions” tutorial, but can’t figure out how to make it work between multiple JFrame forms.
I tried making updateComboBox method public static so it could just be accessed from other forms,
but the NetBeans IDE refused to allow it since the auto-generated non-static variable jComboBox cannot be referenced from a static context.
The primary form contains a JComboBox that needs to be modified based on user input (menus, buttons, text fields, etc.).
Some of the widgets are on the primary form, others are on secondary forms.
For example, the primary form makes a secondary form visible; the secondary form makes some changes to the configuration; then the user hides the secondary form by pressing the SAVE button.
How can the secondary form best let the primary form know that the configuration has been updated and changes now need to be applied to the JComboBox?
Is an Action a good fit for this or would some other method be more appropriate?

public class Controller extends javax.swing.JFrame {
    ...
    private javax.swing.JComboBox jComboBox;
    private void updateComboBox() {
        String[] names = Configuration.getNames();
        for (String n : names) {
            jComboBox.addItem(n);
        }
        ...

Answer 1

How about a controller class which will hold references to your frames and manage the signaling you need? You can also take a look at the Observer pattern, where your primary form will listen the changes made by the secondary form.