ComponentResized not called in certain situations

Question

please try the following code:
public class ResizeTest
    public static void main(String[] args)
        JFrame frame = new JFrame();
        frame.setSize(new Dimension(200, 200));
        JPanel panel = new JPanel();
        panel.setBackground(Color.GREEN);
        frame.setLayout(new BorderLayout());
        frame.add(panel);
        ComponentAdapter adaptor = new ComponentAdapter()
            public void componentResized(ComponentEvent e)
                System.out.println("resized");
        frame.addComponentListener(adaptor);
        frame.setVisible(true);
}When you launch the frame, right-click the title bar of the frame, then select Size. Don't actually resize anything, just left click anywhere in the frame to get out of the resize mode. Now, click the frame's maximize button. You can see that it doesn't get into the componentResized method, and also the green panel, which normally resizes with the frame, doesn't get resized.
This is probably a bug, but anyone know of a workaround?

Answer 1

Looks like a bug, yes. Here's a workaround.
I assume from your code you're using JDK 1.5+ in which case you can drop the first two getContentPane() calls if you must, but not the third (the component listener must listen to the content pane in order to receive all resize events with this workaround).
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Window;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;
import java.awt.event.WindowEvent;
import java.awt.event.WindowStateListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class ResizeTest
    public static void main(String[] args)
        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(new Dimension(200, 200));
        JPanel panel = new JPanel();
        panel.setBackground(Color.GREEN);
        frame.getContentPane().setLayout(new BorderLayout());
        frame.getContentPane().add(panel);
        ComponentAdapter adaptor = new ComponentAdapter()
            public void componentResized(ComponentEvent e)
                System.out.println("resized");
        WindowStateListener windowStateListener = new WindowStateListener()
             public void windowStateChanged(WindowEvent e)
                  Window w = e.getWindow();
                  w.invalidate();
                  w.validate();
        frame.getContentPane().addComponentListener(adaptor);
        frame.addWindowStateListener(windowStateListener);
        frame.setVisible(true);
}