找不到javax.swing.joptionPane的Netbeans异常类

Question

我对Java和Netbeans平台编程非常熟悉，我在10个Netbeans API（文件系统）的示例中遇到了这个非常奇怪的问题。我使用的是Ubuntu 14.10,Java JDK 8,Netbeans 8.0.1

我想在点击菜单元素后在swing消息框中显示一些数据。导入很好,dep库很好,所有编译都很好。但当我点击我的超级菜单项时,我有例外：

java.lang.ClassNotFoundException: javax.swing.JOptionPane not found by org.netbeans.word.module.fsdemo [42]
    at org.apache.felix.framework.BundleWiringImpl.findClassOrResourceByDelegation(BundleWiringImpl.java:1532)
    at org.apache.felix.framework.BundleWiringImpl.access$400(BundleWiringImpl.java:75)
    at org.apache.felix.framework.BundleWiringImpl$BundleClassLoader.loadClass(BundleWiringImpl.java:1955)
Caused: java.lang.ClassNotFoundException: *** Class 'javax.swing.JOptionPane' was not found because bundle org.netbeans.word.module.fsdemo [42] does not import 'javax.swing' even though bundle org.apache.felix.framework [0] does export it. Additionally, the class is also available from the system class loader. There are two fixes: 1) Add an import for 'javax.swing' to bundle org.netbeans.word.module.fsdemo [42]; imports are necessary for each class directly touched by bundle code or indirectly touched, such as super classes if their methods are used. 2) Add package 'javax.swing' to the 'org.osgi.framework.bootdelegation' property; a library or VM bug can cause classes to be loaded by the wrong class loader. The first approach is preferable for preserving modularity. ***
    at org.apache.felix.framework.BundleWiringImpl$BundleClassLoader.loadClass(BundleWiringImpl.java:1968)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
Caused: java.lang.NoClassDefFoundError: javax/swing/JOptionPane
    at org.netbeans.word.module.fsdemo.MenuViewer.actionPerformed(MenuViewer.java:33)
    at org.openide.awt.AlwaysEnabledAction$1.run(AlwaysEnabledAction.java:199)
    at org.openide.util.actions.ActionInvoker$1.run(ActionInvoker.java:95)
    at org.openide.util.actions.ActionInvoker.doPerformAction(ActionInvoker.java:116)
    at org.openide.util.actions.ActionInvoker.invokeAction(ActionInvoker.java:99)
    at org.openide.awt.AlwaysEnabledAction.actionPerformed(AlwaysEnabledAction.java:202)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2346)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
    at javax.swing.AbstractButton.doClick(AbstractButton.java:376)
    at javax.swing.plaf.basic.BasicMenuItemUI.doClick(BasicMenuItemUI.java:833)
    at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(BasicMenuItemUI.java:877)
    at java.awt.Component.processMouseEvent(Component.java:6525)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
    at java.awt.Component.processEvent(Component.java:6290)
    at java.awt.Container.processEvent(Container.java:2234)
    at java.awt.Component.dispatchEventImpl(Component.java:4881)
    at java.awt.Container.dispatchEventImpl(Container.java:2292)
    at java.awt.Component.dispatchEvent(Component.java:4703)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4898)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4533)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4462)
    at java.awt.Container.dispatchEventImpl(Container.java:2278)
    at java.awt.Window.dispatchEventImpl(Window.java:2739)
    at java.awt.Component.dispatchEvent(Component.java:4703)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:746)
    at java.awt.EventQueue.access$400(EventQueue.java:97)
    at java.awt.EventQueue$3.run(EventQueue.java:697)
    at java.awt.EventQueue$3.run(EventQueue.java:691)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:86)
    at java.awt.EventQueue$4.run(EventQueue.java:719)
    at java.awt.EventQueue$4.run(EventQueue.java:717)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:716)
    at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:159)
[catch] at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)

我试图导入所有javax.spring.*包，但它根本不起作用。有趣的是，因为在其他类型的模块的类（如windows）中，相同的代码可以正常工作。下面是我想要复习的代码：

    package org.netbeans.word.module.fsdemo;

    import java.awt.event.ActionEvent;
    import java.awt.event.ActionListener;
    import javax.swing.JOptionPane;
    import org.openide.awt.ActionID;
    import org.openide.awt.ActionReference;
    import org.openide.awt.ActionRegistration;
    import org.openide.filesystems.FileObject;
    import org.openide.filesystems.FileUtil;
    import org.openide.util.NbBundle.Messages;

    @ActionID(
            category = "Edit",
            id = "org.netbeans.word.module.fsdemo.MenuViewer"
    )
    @ActionRegistration(
            displayName = "#CTL_MenuViewer"
    )
    @ActionReference(path = "Menu/Edit", position = 2600, separatorBefore = 2550, separatorAfter = 2650)
    @Messages("CTL_MenuViewer=Viewer")
    public final class MenuViewer implements ActionListener {

        private FileObject root;
        private FileObject dir;

        @Override
        public void actionPerformed(ActionEvent event) {
            root = FileUtil.getConfigRoot();
            dir = root.getFileObject("Menu");
            for (FileObject oneItem : dir.getChildren()) {
                JOptionPane.showMessageDialog(null, "Info", oneItem.getName(), JOptionPane.INFORMATION_MESSAGE);
            }
        }
    }

Answer 1

这是因为使用了OSGi框架。OSGi是模块化系统的标准，其中模块（由一些（版本化的）JAR组成的“bundle”）可能与其他模块相关而被孤立地加载。它有一个终身管理和模块的分离--用特定的类加载器实现。

这是一个比Java提供的更加严格的模块化系统，具有可见性和指定的版本依赖关系。一些特征最终将被纳入Java。

因此为Swing添加一个bundle依赖项。不幸的是，我现在没有NetBeans IDE来检查。