JOptionPane：设置外观后，安装“自定义”图标无效

JOptionPane.showMessageDialog(frame,
    \"Eggs are not supposed to be green.\",
    \"Inane custom dialog\",
    JOptionPane.INFORMATION_MESSAGE,
    myCustomIcon);

import java.net.URL;
import javax.swing.ImageIcon;
import javax.swing.JOptionPane;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class OptionPaneIcon {
    public static void main (String[] args) {
        ImageIcon myCustomIcon = loadImageIcon(\"image.png\");
        UIManager.put(\"OptionPane.informationIcon\", myCustomIcon);
        try {
            UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        } catch (ClassNotFoundException ex) {
        } catch (InstantiationException ex) {
        } catch (IllegalAccessException ex) {
        } catch (UnsupportedLookAndFeelException ex) {
        }
        JOptionPane.showMessageDialog(null, \"Hello!\");
    }

    /** Returns an ImageIcon, or null if the path was invalid. */
    private static ImageIcon loadImageIcon(String path) {
        URL imgURL = OptionPaneIcon.class.getResource(path);
        if (imgURL != null) {
            return new ImageIcon(imgURL);
        } else {
            System.err.println(\"Couldn\'t find file: \" + path);
                return null;
        }
    }
}