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);
    }
}

@yole It's a gradle project and I've chosen to run with the generated main function. — user2798694, Jul 30 '15 at 11:22

score 20 · Accepted Answer · answered Jul 30 '15 at 11:35

20

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.

answered Jul 30 '15 at 11:35

yole

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3

This worked, but doing a gradle rebuild didn't fix it right away until I had specifically right clicked on the Forms Java file and selected recompile. – Kevin Sadler Jul 24 '17 at 09:55
I had the same problem with Gradle but this answer did not solve it, even after rebuilding the Form separately. I ended up converting the project to Maven and now it compiles and runs just fine. – moonlightcheese May 26 '19 at 08:05

score 3 · Answer 2 · answered Sep 04 '19 at 07:25

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

Swing GUI Builder Intellij IDEA

2 Answers2