如何更改NetBeans中Java Swing应用程序的默认样式？

预览模式中几乎没有样式，但找不到可以设置首选设计的位置。有什么选择吗？ 示例：

• 以编程方式：

  UIManager.setLookAndFeel（“com.sun.java.swing.plaf.gtk.GTKLookAndFeel”）
  
  

• 命令行：

  java-Dswing.defaultlaf=com.sun.java.swing.plaf.gtk.GTKLookAndFeel MyApp

你可以在网站上找到更多关于这方面的信息

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完整的演示（来自文档）：

public class LookAndFeelDemo implements ActionListener {
    private static String labelPrefix = "Number of button clicks: ";
    private int numClicks = 0;
    final JLabel label = new JLabel(labelPrefix + "0    ");

    // Specify the look and feel to use by defining the LOOKANDFEEL constant
    // Valid values are: null (use the default), "Metal", "System", "Motif",
    // and "GTK"
    final static String LOOKANDFEEL = "Metal";
    
    // If you choose the Metal L&F, you can also choose a theme.
    // Specify the theme to use by defining the THEME constant
    // Valid values are: "DefaultMetal", "Ocean",  and "Test"
    final static String THEME = "Test";
    

    public Component createComponents() {
        JButton button = new JButton("I'm a Swing button!");
        button.setMnemonic(KeyEvent.VK_I);
        button.addActionListener(this);
        label.setLabelFor(button);

        JPanel pane = new JPanel(new GridLayout(0, 1));
        pane.add(button);
        pane.add(label);
        pane.setBorder(BorderFactory.createEmptyBorder(
                                        30, //top
                                        30, //left
                                        10, //bottom
                                        30) //right
                                        );

        return pane;
    }

    public void actionPerformed(ActionEvent e) {
        numClicks++;
        label.setText(labelPrefix + numClicks);
    }

    private static void initLookAndFeel() {
        String lookAndFeel = null;
       
        if (LOOKANDFEEL != null) {
            if (LOOKANDFEEL.equals("Metal")) {
                lookAndFeel = UIManager.getCrossPlatformLookAndFeelClassName();
              //  an alternative way to set the Metal L&F is to replace the 
              // previous line with:
              // lookAndFeel = "javax.swing.plaf.metal.MetalLookAndFeel";
                
            }
            
            else if (LOOKANDFEEL.equals("System")) {
                lookAndFeel = UIManager.getSystemLookAndFeelClassName();
            } 
            
            else if (LOOKANDFEEL.equals("Motif")) {
                lookAndFeel = "com.sun.java.swing.plaf.motif.MotifLookAndFeel";
            } 
            
            else if (LOOKANDFEEL.equals("GTK")) { 
                lookAndFeel = "com.sun.java.swing.plaf.gtk.GTKLookAndFeel";
            } 
            
            else {
                System.err.println("Unexpected value of LOOKANDFEEL specified: "
                                   + LOOKANDFEEL);
                lookAndFeel = UIManager.getCrossPlatformLookAndFeelClassName();
            }

            try {
                
                
                UIManager.setLookAndFeel(lookAndFeel);
                
                // If L&F = "Metal", set the theme
                
                if (LOOKANDFEEL.equals("Metal")) {
                  if (THEME.equals("DefaultMetal"))
                     MetalLookAndFeel.setCurrentTheme(new DefaultMetalTheme());
                  else if (THEME.equals("Ocean"))
                     MetalLookAndFeel.setCurrentTheme(new OceanTheme());
                  else
                     MetalLookAndFeel.setCurrentTheme(new TestTheme());
                     
                  UIManager.setLookAndFeel(new MetalLookAndFeel()); 
                }   
                    
                    
                  
                
            } 
            
            catch (ClassNotFoundException e) {
                System.err.println("Couldn't find class for specified look and feel:"
                                   + lookAndFeel);
                System.err.println("Did you include the library in the class path?");
                System.err.println("Using the default look and feel.");
            } 
            
            catch (UnsupportedLookAndFeelException e) {
                System.err.println("Can't use the specified look and feel ("
                                   + lookAndFeel
                                   + ") on this platform.");
                System.err.println("Using the default look and feel.");
            } 
            
            catch (Exception e) {
                System.err.println("Couldn't get specified look and feel ("
                                   + lookAndFeel
                                   + "), for some reason.");
                System.err.println("Using the default look and feel.");
                e.printStackTrace();
            }
        }
    }

    private static void createAndShowGUI() {
        //Set the look and feel.
        initLookAndFeel();

        //Make sure we have nice window decorations.
        JFrame.setDefaultLookAndFeelDecorated(true);

        //Create and set up the window.
        JFrame frame = new JFrame("SwingApplication");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        LookAndFeelDemo app = new LookAndFeelDemo();
        Component contents = app.createComponents();
        frame.getContentPane().add(contents, BorderLayout.CENTER);

        //Display the window.
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        //Schedule a job for the event dispatch thread:
        //creating and showing this application's GUI.
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }
}