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更改特定窗口的外观和感觉

javaswingnullpointerexceptionlook-and-feel
4
我正在为一个大型GUI应用程序编写脚本。主要的应用程序窗口使用系统的LookAndFeel，但我希望我的脚本的GUI使用Nimbus LookAndFeel。在创建GUI后，我想将LookAndFeel设置回原来的状态。我认为下面的SSCCE应该可以工作，但是当我使用我的Component对象时，我遇到了NullPointerException。
import java.awt.Dimension;
import java.awt.GridBagLayout;
import javax.swing.*;
import javax.swing.UIManager.LookAndFeelInfo;

public class GUI extends JFrame {
    private static LookAndFeel originalLookAndFeel = UIManager.getLookAndFeel();
    static {
        System.out.println("At start, look and feel is " + UIManager.getLookAndFeel().getName());
        try {
            setNimbusLookAndFeel();
        } catch (Exception e) {
            System.out.println(e.getMessage());
        }
        System.out.println("Look and feel changed to " + UIManager.getLookAndFeel().getName()
                + " before component creation");
    }
    private GridBagLayout gridBag = new GridBagLayout();
    private JTabbedPane tabs = new JTabbedPane();
    private JPanel selectionPanel = new JPanel(gridBag);
    private JPanel infoPanel = new JPanel(gridBag);
    private JPanel settingsPanel = new JPanel(gridBag);

    public GUI() {
        setWindowProperties();
        setUpComponents();
        addComponents();

        try {
            System.out.println("Setting to original, which is " + originalLookAndFeel.getName());
            UIManager.setLookAndFeel(originalLookAndFeel);
            System.out.println("Current look and feel is " + UIManager.getLookAndFeel().getName());
        } catch (UnsupportedLookAndFeelException e) {
            e.printStackTrace();
        }
    }

    private void setWindowProperties() {
        setLayout(gridBag);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(new Dimension(700, 600));
        setTitle("fAmos Quester");
        setResizable(false);
        setLocationRelativeTo(null);
    }

    private static void setNimbusLookAndFeel() {
        try {
            for (LookAndFeelInfo info : UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    UIManager.setLookAndFeel(info.getClassName());
                }
            }
        } catch (Exception e) {
            try {
                UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
            } catch (Exception e2) {
            }
        }
    }

    public void setUpComponents() {
        tabs.addTab("Quest selection", selectionPanel);
        tabs.addTab("Quest info", infoPanel);
        tabs.addTab("Settings", settingsPanel);

        selectionPanel.setPreferredSize(new Dimension(650, 500));
        infoPanel.setPreferredSize(new Dimension(650, 500));
        settingsPanel.setPreferredSize(new Dimension(650, 500));
    }

    private void addComponents() {
        add(tabs);
    }

    public static void main(String[] args) {
        new GUI().setVisible(true);
    }
}
4个回答
6
作为一般规则，混合使用不同的LAF（外观和感觉）并不是一个好主意。这个问题就是为什么。
Nimbus LAF中有一些东西可能不允许您这样做。按原样运行代码。它将把LAF设置为“系统LAF”，然后重置LAF。在我的情况下，系统是Windows，看起来工作正常。然后将代码更改为使用Nimbus LAF。最初似乎可以工作，但尝试调整框架大小会导致错误。因此，似乎Nimbus框架不能完全独立于当前的LAF工作。
import java.awt.*;
import java.awt.event.*;
import java.awt.GridBagLayout;
import javax.swing.*;
import javax.swing.UIManager.LookAndFeelInfo;

public class GUI2 extends JFrame {
    private static LookAndFeel originalLookAndFeel = UIManager.getLookAndFeel();
/*
    private GridBagLayout gridBag = new GridBagLayout();
    private JTabbedPane tabs = new JTabbedPane();
    private JPanel selectionPanel = new JPanel(gridBag);
    private JPanel infoPanel = new JPanel(gridBag);
    private JPanel settingsPanel = new JPanel(gridBag);
*/
    private GridBagLayout gridBag;
    private JTabbedPane tabs;
    private JPanel selectionPanel;
    private JPanel infoPanel;
    private JPanel settingsPanel;

    public GUI2() {
        System.out.println("At start, look and feel is " + UIManager.getLookAndFeel().getName());
        try {
//            setNimbusLookAndFeel();
          UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        } catch (Exception e) {
            e.printStackTrace();
        }
        System.out.println("Look and feel changed to " + UIManager.getLookAndFeel().getName()
                + " before component creation");

        gridBag = new GridBagLayout();
        setLayout(gridBag);
        tabs = new JTabbedPane();
        selectionPanel = new JPanel(gridBag);
        infoPanel = new JPanel(gridBag);
        settingsPanel = new JPanel(gridBag);

        setUpComponents();
        addComponents();
        setWindowProperties();

        Action reset = new AbstractAction()
        {
            public void actionPerformed(ActionEvent ae)
            {
                try {
                    System.out.println("Setting to original, which is " + originalLookAndFeel.getName());
                    UIManager.setLookAndFeel(originalLookAndFeel);
                    System.out.println("Current look and feel is " + UIManager.getLookAndFeel().getName());
                } catch (UnsupportedLookAndFeelException e) {
                    //e.printStackTrace();
                    System.out.println(e.getMessage());
                }

            }
        };

        Timer timer = new Timer(500, reset);
        timer.setRepeats(false);
        timer.start();
    }

    private void setWindowProperties() {
//        setLayout(gridBag);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setTitle("fAmos Quester");
//        setResizable(false);
        pack();
        setLocationRelativeTo(null);
    }

    private void setNimbusLookAndFeel() {
        try {
            for (LookAndFeelInfo info : UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    UIManager.setLookAndFeel(info.getClassName());
                }
            }
        } catch (Exception e) {
            try {
                UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
            } catch (Exception e2) {
            }
        }
    }

    public void setUpComponents() {
        tabs.addTab("Quest selection", selectionPanel);
        tabs.addTab("Quest info", infoPanel);
        tabs.addTab("Settings", settingsPanel);

        selectionPanel.setPreferredSize(new Dimension(650, 500));
        infoPanel.setPreferredSize(new Dimension(650, 500));
        settingsPanel.setPreferredSize(new Dimension(650, 500));
    }

    private void addComponents() {
        add(tabs);
    }

    public static void main(String[] args) {
        new GUI2().setVisible(true);
    }
}

也许一个解决方案是使用Nimbus LAF创建组件，就像上面所做的那样。但是，在窗口未被停用之前，请不要重置LAF。然后，您可以尝试在每次激活窗口时重置LAF。您将使用WindowListener来处理已激活/停用事件。
我正在考虑切换到JDialog。那么我需要添加一个窗口监听器并在关闭时更改LAF吗？ - Joel Christophel
如果您正在使用模态JDialog，那么这可能是值得尝试的。再次强调，这只是我的猜测。 - camickr
3
问题源于试图在静态块中进行PLAF更改。将其移动到构造函数中即可解决问题。
import java.awt.Dimension;
import java.awt.GridBagLayout;
import javax.swing.*;
import javax.swing.UIManager.LookAndFeelInfo;

public class GUI extends JFrame {
    private static LookAndFeel originalLookAndFeel = UIManager.getLookAndFeel();
    private GridBagLayout gridBag = new GridBagLayout();
    private JTabbedPane tabs = new JTabbedPane();
    private JPanel selectionPanel = new JPanel(gridBag);
    private JPanel infoPanel = new JPanel(gridBag);
    private JPanel settingsPanel = new JPanel(gridBag);

    public GUI() {
        System.out.println("At start, look and feel is " + UIManager.getLookAndFeel().getName());
        try {
            setNimbusLookAndFeel();
        } catch (Exception e) {
            e.printStackTrace();
        }
        System.out.println("Look and feel changed to " + UIManager.getLookAndFeel().getName()
                + " before component creation");

        setWindowProperties();
        setUpComponents();
        addComponents();

        try {
            System.out.println("Setting to original, which is " + originalLookAndFeel.getName());
            UIManager.setLookAndFeel(originalLookAndFeel);
            System.out.println("Current look and feel is " + UIManager.getLookAndFeel().getName());
        } catch (UnsupportedLookAndFeelException e) {
            //e.printStackTrace();
            System.out.println(e.getMessage());
        }
    }

    private void setWindowProperties() {
        setLayout(gridBag);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(new Dimension(700, 600));
        setTitle("fAmos Quester");
        setResizable(false);
        setLocationRelativeTo(null);
    }

    private void setNimbusLookAndFeel() {
        try {
            for (LookAndFeelInfo info : UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    UIManager.setLookAndFeel(info.getClassName());
                }
            }
        } catch (Exception e) {
            try {
                UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
            } catch (Exception e2) {
            }
        }
    }

    public void setUpComponents() {
        tabs.addTab("Quest selection", selectionPanel);
        tabs.addTab("Quest info", infoPanel);
        tabs.addTab("Settings", settingsPanel);

        selectionPanel.setPreferredSize(new Dimension(650, 500));
        infoPanel.setPreferredSize(new Dimension(650, 500));
        settingsPanel.setPreferredSize(new Dimension(650, 500));
    }

    private void addComponents() {
        add(tabs);
    }

    public static void main(String[] args) {
        new GUI().setVisible(true);
    }
}
我不再遇到运行时异常，但我的窗口外观不是Nimbus。由于组件是在外观不是Nimbus的情况下创建的，它们不会显示为Nimbus。最初，我使用静态块来确保在创建组件之前将Nimbus设置为外观。 - Joel Christophel
你能展示一个更好地代表实际问题的SSCCE吗？另外，如果已经有一个框架，这个GUI应该是一个对话框。请参阅《使用多个JFrames，好/坏的做法？》（https://dev59.com/Wmkw5IYBdhLWcg3w8O6o#9554657）。 - Andrew Thompson
比如说GUI（含糊不清的方式）-那是你的GUI还是主要的GUI？你提到了多个“窗口”，但是你的SSCCE只创建了一个窗口。 - Andrew Thompson
我没有编写主应用程序的代码。我正在编写一个插件。因此，我所引用的唯一窗口是我的插件窗口。 - Joel Christophel
"我没有编写主应用程序的代码"。也许不是，但“一个”主应用程序只需要几行额外的代码。这应该包含在SSCCE中。 - Andrew Thompson
3
一般情况下，LAFs无法混合使用，它们的设计是确保在任何应用程序中，所有组件都只有一个。因此，混合使用的结果是未定义的。在具体情况下，您可能会成功或失败，但是请准备好出现意外的视觉和感觉效果。
以下是一个示例，演示了混合使用可能导致的视觉效果（在SwingX测试基础设施中完成，足够简单，但我太懒了;-) - 打开optionPane，然后将其移动：您将看到Nimbus条纹颜色以更或少不可预测的方式出现）。
setLAF("Metal");
final JTable table = new JTable(new AncientSwingTeam()); 
JXFrame frame = wrapWithScrollingInFrame(table, "Metal-base");
Action action = new AbstractAction("show dialog") {

    @Override
    public void actionPerformed(ActionEvent e) {
        setLAF("Nimbus");
        JOptionPane.showMessageDialog(table, "dummy - we are Nimbus!");
        setLAF("Metal");
    }
};
addAction(frame, action);
show(frame);

技术原因是ui-delegates可以随时访问存储在UIManager中的属性：主要是在实例化时从UIManager中配置组件的属性，然后从组件中访问这些属性。偶尔，它们会直接访问UIManager...从而导致不可预测的结果。

0

这个解决方案假设您将更改“此”特定窗口的外观设置（一个小的私有辅助方法）。我使用对话框窗口从用户那里获取输入（您可以重新设计它以隐藏它并在需要时进行更改）。当然，为了清晰起见，这有点长，可以轻松缩短。

private void changeLookAndFeel() {
        final LookAndFeelInfo[] list = UIManager.getInstalledLookAndFeels();
        //Look And Feels available 


            final List<String> lookAndFeelsDisplay = new ArrayList<>();
            final List<String> lookAndFeelsRealNames = new ArrayList<>();

            for (LookAndFeelInfo each : list) {
                lookAndFeelsDisplay.add(each.getName()); //simplified name of each available look and feel
                lookAndFeelsRealNames.add(each.getClassName()); //class name
            }

            if (lookAndFeelsDisplay.size() != lookAndFeelsRealNames.size()) {
                throw new InternalError(); //should never happen, redundant
            }

            String changeSpeed = (String) JOptionPane.showInputDialog(this, "Choose Look and Feel Here\n(these are all available on your system):", "Choose Look And Feel", JOptionPane.QUESTION_MESSAGE, null, lookAndFeelsDisplay.toArray(), null);

            boolean update = false;
            if (changeSpeed != null && changeSpeed.length() > 0) {
                for (int a = 0; a < lookAndFeelsDisplay.size(); a++) {
                    if (changeSpeed.equals(lookAndFeelsDisplay.get(a))) {
                        try {
                            UIManager.setLookAndFeel(lookAndFeelsRealNames.get(a)); //reads the identical class name at the corresponding index position.
                            this.whichLookAndFeel = changeSpeed;
                            update = true;
                            break;
                        }
                        catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                            err.println(ex);
                            ex.printStackTrace();
                            Logger.getLogger(MyClass.class.getName()).log(Level.SEVERE, null, ex);
                        }
                    }
                }
            }

            if (update) {
                // make updates here...
            }
    }
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