SwingUtilities.updateComponentTreeUI() not changing JFrames titlebar

问题

Environment:

Using Netbeans 8.1

Oracle JDK 1.8

Win 10 pro

Context:

A GUI with a JCheckBoxMenuItem to change LookAndFeel(LAF) at runtime.

darkLAF=JTattoo's HiFi LAF

defaultLAF=Sun's Windows LAF(com.sun.java.swing.plaf.windows.WindowsLookAndFeel)

Problem:

1. GUI launches(in EDT) with defaultLAF. User changes to darkLAF..the title bar should have changed..it doesn't.

2. When the user switches back to defaultLAF, the JMenuItems(File and Edit) show greyer backgrounds not the defaultLAF style.

Screenshots:

1. The launched defaultLAF

2. upon switching to darkLAF

3. user switched back to defaultLAF
4. expected look for darkLAF

Code:

1. Inside the itemStateChangeListener for JCheckBoxMenuItem

   try{
      if (checkBox.isSelected())                                                                 
         UIManager.setLookAndFeel(darkLookAndFeel);
      else
       UIManager.setLookAndFeel(defaultLookAndFeel);
   
   
   } catch (UnsupportedLookAndFeelException ex) {
      //handle err
   }
   
   //GUI is a class extending JFrame        
   SwingUtilities.updateComponentTreeUI(this);
   //some JFileChooser
   SwingUtilities.updateComponentTreeUI(fc);
   
   pack();
   

Catch:

1. User shouldn't be asked to do a GUI restart.

回答1:

It was a little bit hard, but I've found a solution.

Steps you need to switch to the JTatto L&F

1. Dispose window
2. Set L&F
3. Set window style of root pane to JRootPane.FRAME
4. Update UI
5. Make Frame undecorated
6. Make Frame visible

Steps you need to switch back to Windows L&F

1. Dispose window
2. Set L&F
3. Update UI
4. Make Frame decorated
5. Make Frame visible

Here is the code

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

public class MinFrame extends JFrame {

    public MinFrame() {
        super("Minimal-Frame-Application");

        // setup menu
        JMenuBar menuBar = new JMenuBar();
        JMenu menu = new JMenu("File");
        menu.setMnemonic('F');
        JMenuItem menuItem = new JMenuItem("Exit");
        menuItem.setMnemonic('x');
        menuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_F4, KeyEvent.ALT_MASK));
        menuItem.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent event) {
                System.exit(0);
            }
        });
        menu.add(menuItem);
        menuBar.add(menu);
        setJMenuBar(menuBar);

        // setup widgets
        JPanel contentPanel = new JPanel(new BorderLayout());
        contentPanel.setBorder(BorderFactory.createEmptyBorder(0, 4, 4, 4));
        JScrollPane westPanel = new JScrollPane(new JTree());
        JEditorPane editor = new JEditorPane("text/plain", "Hello World");
        JScrollPane eastPanel = new JScrollPane(editor);
        JSplitPane splitPane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, true, westPanel,eastPanel);
        splitPane.setDividerLocation(148);
        contentPanel.add(splitPane, BorderLayout.CENTER);


        AbstractButton winLF = new JButton("Windows");
        winLF.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                try {
                    MinFrame.this.dispose();
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                    SwingUtilities.updateComponentTreeUI(MinFrame.this.getRootPane());

                    MinFrame.this.setUndecorated(false);
                    MinFrame.this.setVisible(true);
                } catch (Exception ex) {
                    ex.printStackTrace();
                }
            }
        });
        AbstractButton customLF = new JButton("JTatto");
        customLF.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                try {
                    MinFrame.this.dispose();
                    UIManager.setLookAndFeel("com.jtattoo.plaf.smart.SmartLookAndFeel");
                    MinFrame.this.getRootPane().setWindowDecorationStyle(JRootPane.FRAME);
                    SwingUtilities.updateComponentTreeUI(MinFrame.this.getRootPane());

                    MinFrame.this.setUndecorated(true);
                    MinFrame.this.setVisible(true);
                } catch (Exception ex) {
                    ex.printStackTrace();
                }
            }
        });

        JPanel buttons = new JPanel();
        buttons.add(winLF);
        buttons.add(customLF);
        contentPanel.add(buttons, BorderLayout.SOUTH);
        setContentPane(contentPanel);

        // add listeners
        addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });

        // show application
        setLocation(32, 32);
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        setSize(400, 300);
        setVisible(true);
    } // end CTor MinFrame

    public static void main(String[] args) {
        try {
            // select Look and Feel
//            UIManager.setLookAndFeel("com.jtattoo.plaf.smart.SmartLookAndFeel");
            // start application
            new MinFrame();
        }
        catch (Exception ex) {
            ex.printStackTrace();
        }
    } // end main

}

来源：https://stackoverflow.com/questions/51595444/swingutilities-updatecomponenttreeui-not-changing-jframes-titlebar