Swing GUI error

Hi there, I'm trying to create java application using swing GUI. I've added JButton on the form, checked the "Custom Create" option in inspector, but the compiler throws an error.

Main.java

public class Main {

    public static void main(String[] args) {

        Form MyForm = new Form();

    }

}

Form.java

import javax.swing.*;

public class Form extends JFrame{

    private JButton button1;

    private void createUIComponent()

    {

        button1 = new JButton();

    }

}