Question

I’m completely new to Linux and have been trying to get my (Windows built) Java Swing projects to work correctly on XUbuntu on a separate machine from executable jar files I built.

I’ve reduced the problem to a minimum amount of code

import java.awt.Dimension;
import javax.swing.*;

public class JFrameTest extends JFrame {

    public JFrameTest(String title) {
        super(title);
        JLabel lab = new JLabel("Label");
        this.getContentPane().add(lab);
        this.setMinimumSize(new Dimension(200, 200));
        this.pack();
        this.setVisible(true);
    }

    public static void main(String args[]) {
        try {
            UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        JFrameTest frame = new JFrameTest("Title");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }

}

On Windows I see:

In Xubuntu I just see a grey box and the label, not the Title or close icons etc. I also have to kill (-9) the jvm after I’ve ctrl zedded from the command line. I launched it with java -jar filename.jar

My Linux machine is running Xubuntu 11. I’ve installed the sun Java 6_24 JRE. I Googled for this and found something similar relating to Compziz(?) but this was allegedly fixed a while back. I’m a bit stuck now. I have got one Swing app that works OK in that it responds to buttons OK but still doesn’t show the Title etc. Any help would be much appreciated.

Answer 1

I don’t use Xubuntu, but the general rule is that any code that updates a GUI should be executed on the Event Dispatch Thread. See the section from the Swing tutorial on Concurrency.

The examples from the Swing tutorial all use a format like this:

import java.awt.*;
import javax.swing.*;
import javax.swing.text.*;

public class SSCCE extends JPanel
{
    public SSCCE()
    {
        add( new JLabel("Label") );
    }

    private static void createAndShowUI()
    {
        JFrame frame = new JFrame("SSCCE");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add( new SSCCE() );
        frame.pack();
        frame.setLocationRelativeTo( null );
        frame.setVisible( true );
    }

    public static void main(String[] args)
    {
        EventQueue.invokeLater(new Runnable()
        {
            public void run()
            {
                createAndShowUI();
            }
        });
    }
}