Swing GUI Builder Intellij IDEA

Question

I can't seem to run a form on IntelliJ GUI builder

Exception in thread "main" java.awt.IllegalComponentStateException: contentPane cannot be set to null.

I assume the code to initialize the views are auto generated. Right now I only have a JPanel and somehow it is not auto-initialized even thought it's clearly visible on the designer.

It's a Gradle project and I've chosen to run with the generated main function.

What do I have to do to get it working?

public class MyForm {

    private JPanel jPanel;

    public static void main(String[] args) {
        JFrame frame = new JFrame("MyForm");
        frame.setContentPane(new MyForm().jPanel);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack();
        frame.setVisible(true);
    }
}

Answer 1

By default, the IntelliJ IDEA UI designer works by generating bytecode, which is unfortunately not supported with Gradle builds. You can change it to generate source code in Settings | Editor | GUI Designer.

Answer 2

see Intellij (Swing) GUI not compiling because of Gradle

solved by changing intellij settings (also see the screenshot)

i've checked:

• automaticaly import ...
• build and run using - set - intellij
• run tests using - set - intellij
• Gradle JVM - set - Use project JDK