java - 这个: Exception in thread "AWT-EventQueue-0" java. lang.ExceptionInInitializerError是什么？

Question

我复制了一个java程序(称为SwingAccumulator.java)，它使用户能够在GUI中一一输入整数并打印当前的总和。然后我复制了别人编写的一个类(称为 createGraph())来绘制折线图。我正在尝试将两者结合起来，调用程序 ODESolver.java。第二部分(createGraph())使用 JFreeChart。我刚刚尝试从 SwingAccumulator 部分调用 createGraph() 方法，但出现以下错误:

线程“AWT-EventQueue-0”中的异常 java.lang.ExceptionInInitializerError

任何人都可以帮助我了解导致这些错误的原因以及如何修复它们吗？

我的错误的完整详细信息如下:

Exception in thread "AWT-EventQueue-0" java.lang.ExceptionInInitializerError
    at odesolver.ODESolver.createGraph(ODESolver.java:66)
    at odesolver.ODESolver.<init>(ODESolver.java:60)
    at odesolver.ODESolver$2.run(ODESolver.java:101)
    at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:251)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:733)
    at java.awt.EventQueue.access$200(EventQueue.java:103)
    at java.awt.EventQueue$3.run(EventQueue.java:694)
    at java.awt.EventQueue$3.run(EventQueue.java:692)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:703)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)
Caused by: java.lang.RuntimeException: Uncompilable source code - package org.jfree.util does not exist
    at org.jfree.data.general.Series.<clinit>(Series.java:69)
    ... 17 more  

我想类路径没有正确设置。我刚刚将其设置为包含 jfreechart-1.0.16 文件夹的文件夹。我想知道 JCommon 类路径是否尚未设置，但我认为 JCommon 包含在 jfreechart-1.0.16 文件夹中。

Answer 1

正如 @Foo Bar 用户评论，jfreechart 和 jcommon 都必须位于 classpath 中:

java -cp lib/jfreechart-1.0.16.jar:lib/jcommon-1.0.20.jar 
    org.jfree.chart.demo.TimeSeriesChartDemo1