java - Java Swing 错误 - 未知更改

Question

我已经在基于 Swing 的 java 程序上工作了一段时间了，今天我一直在编辑 JComboBox(使用 Netbeans，所以我无法直接编辑它的代码)，在编辑之间的某个时刻出现以下错误突然出现。 显然，此时涉及的代码太多，无法发布，但是有人知道/经验可能导致此问题的原因吗？

自从出现此错误之前，我没有对源代码进行任何直接更改，但尽管尽了一切努力撤消今天所做的所有更改，但对这些错误没有产生任何影响。我什至尝试过关闭 netbeans 并重新启动它，以防它刚刚运行。

另外，Application 末尾的 $1 表示什么？我以前没见过这个

感谢您的所有建议。

2010 年 10 月 8 日 14:07:07 org.jdesktop.application.Application$1 运行

SEVERE: Application class nodeview.NodeViewApp failed to launch
java.lang.NullPointerException
        at nodeview.NodeViewView.<init>(NodeViewView.java:49)
        at nodeview.NodeViewApp.startup(NodeViewApp.java:19)
        at org.jdesktop.application.Application$1.run(Application.java:171)
        at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:597)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
Exception in thread "AWT-EventQueue-0" java.lang.Error: Application class nodeview.NodeViewApp failed to launch
        at org.jdesktop.application.Application$1.run(Application.java:177)
        at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:597)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
Caused by: java.lang.NullPointerException
        at nodeview.NodeViewView.<init>(NodeViewView.java:49)
        at nodeview.NodeViewApp.startup(NodeViewApp.java:19)
        at org.jdesktop.application.Application$1.run(Application.java:171)
        ... 8 more

根据要求，NodeViewView 中第 37 行到第 50 行的代码

    messageTimer.setRepeats(false);
    int busyAnimationRate = resourceMap.getInteger("StatusBar.busyAnimationRate");
    for (int i = 0; i < busyIcons.length; i++) {
        busyIcons[i] = resourceMap.getIcon("StatusBar.busyIcons[" + i + "]");
    }
    busyIconTimer = new Timer(busyAnimationRate, new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            busyIconIndex = (busyIconIndex + 1) % busyIcons.length;
            statusAnimationLabel.setIcon(busyIcons[busyIconIndex]);
        }
    });
    idleIcon = resourceMap.getIcon("StatusBar.idleIcon");
   statusAnimationLabel.setIcon(idleIcon); //49
   progressBar.setVisible(false); //50

Answer 1

NodeViewView.java:49 是您可以找到错误的地方。最像一个对象尚未正确初始化，而您正在尝试访问该对象的方法或成员变量。