Maximizing a form (JFrame) by default when it opens

[Tim Batts]

I am generating a swing JFrame via NetBeans and the goal is to get it to maximize automatically when the JFrame opens. JFrame is implemented as a class extension of javax.swing.JFrame.

I thought setExtendedState(JFrame.MAXIMIZE_BOTH); would work, but it isn't. Can anyone help?

import javax.swing.*;

public class TestFrame extends javax.swing.JFrame {

    
    public TestFrame() {
        initComponents();
    }

   
    private void initComponents() {

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        setExtendedState(JFrame.MAXIMIZED_BOTH);

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 400, Short.MAX_VALUE)
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 300, Short.MAX_VALUE)
        );

        pack();
    }

[Rob Spoor]

What happens if you move that statement to after the pack() statement?

[Tim Batts]

I can't. The IDE won't let me edit the generated code. Which I think is stupid.

I did find a work around: the generated code for the main is this:

public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
               new TestFrame().setVisible(true);
            }
        });
    }

I replaced it with the following to actually set a reference variable for the form:

public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                TestFrame x = new TestFrame();
                x.setVisible(true);
                x.setExtendedState(JFrame.MAXIMIZED_BOTH);
            }
        });
    }

But I don't understand why running that statement in the constructor would not have maximized the frame. I would think it would work no differently than the previous statement setDefaultCloseOperation and should execute.

Altering the main as I did works, but if someone can confirm for me if that will have other consequences for the application I would appreciate it. Or if there is another way to do it.