java - 使用摇摆时出错

Question

我正在尝试使用一些按钮创建面板，该按钮可以禁用另一个按钮代码完美编译但在运行时显示错误有什么问题。我无法调试这个。

Exception in thread "main" java.lang.NoClassDefFoundError: buttondemo (wrong nam
e: components/buttondemo)
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:791)
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:14
2)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
        at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
        at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:472)

这是代码

import javax.swing.AbstractButton;
import javax.swing.JButton;
import javax.swing.JPanel;
import javax.swing.JFrame;
import javax.swing.ImageIcon;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;

public class buttondemo extends JPanel implements ActionListener {
    private JButton b1, b2, b3;

    public buttondemo() {
        ImageIcon Left = createImageIcon("C:\\Users\\nco\\Desktop\\Swing\\components\\images\\left.png");
        ImageIcon Right = createImageIcon("C:\\Users\\nco\\Desktop\\Swing\\components\\images\\right.jpg");
        ImageIcon Middle = createImageIcon("C:\\Users\\nco\\Desktop\\Swing\\components\\images\\middle.jpg");
        b1 = new JButton("Disable middle button", Left);
        b1.setVerticalTextPosition(AbstractButton.CENTER);
        b1.setMnemonic(KeyEvent.VK_D);// shortcut D
        b1.setActionCommand("disable");
        b2 = new JButton("middle button", Middle);
        b2.setVerticalTextPosition(AbstractButton.BOTTOM);
        b2.setVerticalTextPosition(AbstractButton.CENTER);
        b3.setMnemonic(KeyEvent.VK_M);// shortcut M
        b3 = new JButton("Enable middle button", Right);
        b3.setVerticalTextPosition(AbstractButton.RIGHT);
        b3.setMnemonic(KeyEvent.VK_E);// shortcut E
        b3.setActionCommand("enable");
        b3.setEnabled(false);
        b1.addActionListener(this);
        b3.addActionListener(this);
        b1.setToolTipText("click on the middle button to " + "disable middle");
        b3.setToolTipText("click on the middle button to " + "enable middle");
        b2.setToolTipText("click disable");
        add(b1);
        add(b2);
        add(b3);
    }

    public void actionPerformed(ActionEvent e) {
        if ("disable".equals(e.getActionCommand())) {
            b2.setEnabled(false);
            b1.setEnabled(false);
            b3.setEnabled(true);
        } else {
            b2.setEnabled(true);
            b1.setEnabled(true);
            b3.setEnabled(false);
        }
    }

    protected static ImageIcon createImageIcon(String path) {
        java.net.URL img = buttondemo.class.getResource(path);
        if (img != null) {
            return new ImageIcon(img);
        } else {
            System.err.println("could not find path" + path);
            return null;
        }
    }

    private static void createAndShowGUI() {
        JFrame frame = new JFrame("Button demso");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        buttondemo Contentpane = new buttondemo();
        Contentpane.setOpaque(true);
        frame.setContentPane(Contentpane);
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String args[]) {
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }

}

score 2 · Accepted Answer

b3.setMnemonic(KeyEvent.VK_M);// shortcut M是非JButton初始化的代码行（在下一个代码行中初始化）
并非所有Text 和 Icon 的组合都可以匹配在一起，AbstractButton 也不例外
仅对BorderLayout使用常量

在此处输入图像描述

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingConstants;
import javax.swing.UIManager;

public class buttondemo extends JPanel implements ActionListener {

    private JButton b1, b2, b3;

    public buttondemo() {
        Icon Left = UIManager.getIcon("OptionPane.errorIcon");
        Icon Right = UIManager.getIcon("OptionPane.informationIcon");
        Icon Middle = UIManager.getIcon("OptionPane.warningIcon");
        b1 = new JButton("Disable middle button", Left);
        b1.setVerticalTextPosition(SwingConstants.TOP);
        b1.setHorizontalTextPosition(SwingConstants.CENTER);
        b1.setMnemonic(KeyEvent.VK_D);//shortcut D
        b1.setActionCommand("disable");
        b2 = new JButton("middle button", Middle);
        b2.setVerticalTextPosition(SwingConstants.BOTTOM);
        b2.setHorizontalTextPosition(SwingConstants.LEFT);
        b3 = new JButton("Enable middle button", Right);
        b3.setMnemonic(KeyEvent.VK_M);//shortcut M
        b2.setVerticalTextPosition(SwingConstants.EAST);
        b2.setHorizontalTextPosition(SwingConstants.CENTER);
        b3.setActionCommand("enable");
        b3.setEnabled(false);
        b1.addActionListener(this);
        b3.addActionListener(this);
        b1.setToolTipText("click on the middle button to " + "disable middle");
        b3.setToolTipText("click on the middle button to " + "enable middle");
        b2.setToolTipText("click disable");
        add(b1);
        add(b2);
        add(b3);
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        if ("disable".equals(e.getActionCommand())) {
            b2.setEnabled(false);
            b1.setEnabled(false);
            b3.setEnabled(true);
        } else {
            b2.setEnabled(true);
            b1.setEnabled(true);
            b3.setEnabled(false);
        }
    }

    protected static ImageIcon createImageIcon(String path) {
        java.net.URL img = buttondemo.class.getResource(path);
        if (img != null) {
            return new ImageIcon(img);
        } else {
            System.err.println("could not find path" + path);
            return null;
        }
    }

    private static void createAndShowGUI() {
        JFrame frame = new JFrame("Button demso");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        buttondemo Contentpane = new buttondemo();
        Contentpane.setOpaque(true);
        frame.setContentPane(Contentpane);
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String args[]) {
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                createAndShowGUI();
            }
        });
    }
}

编辑

WinXP 上的 Java6 导致同样的异常

java.lang.NoClassDefFoundError: JButton/ButtonDemo 引起：java.lang.ClassNotFoundException: JButton.ButtonDemo at java.net.URLClassLoader$1.run(URLClassLoader.java:202) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:190) 在 java.lang.ClassLoader.loadClass(ClassLoader.java:307) 在 sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301) 在 java.lang .ClassLoader.loadClass(ClassLoader.java:248) 找不到主类：JButton.ButtonDemo。程序将会退出。线程“main”Java 结果中的异常：1

但必须使用正确private的使用而不是protected static ImageIcon createImageIcon(String path) {导致异常

@看

private ImageIcon createImageIcon(String path) {
    java.net.URL img = ButtonDemo.class.getResource(path);
    if (img != null) {
        return new ImageIcon(img);
    } else {
        System.err.println("could not find path" + path);
        return null;
    }
}

java - 使用摇摆时出错

1 回答 1

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