java - 我刚刚开始使用 jmathplot 并收到此异常消息

Question

我想在我的应用程序中绘制图表，因此我下载了jmathplot.jar并将其添加到我的项目中。

当我向框架添加字段时:

private PlotPanel plot = new Plot2DPanel();

我在编译时收到一条令人讨厌的长异常消息:

Exception in thread "AWT-EventQueue-0" java.lang.NoClassDefFoundError: org/math/io/StringPrintable at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClass(Unknown Source) at java.security.SecureClassLoader.defineClass(Unknown Source) at java.net.URLClassLoader.defineClass(Unknown Source) at java.net.URLClassLoader.access$100(Unknown Source) at java.net.URLClassLoader$1.run(Unknown Source) at java.net.URLClassLoader$1.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at org.math.plot.canvas.PlotCanvas.(PlotCanvas.java:491) at org.math.plot.canvas.Plot2DCanvas.(Plot2DCanvas.java:25) at org.math.plot.Plot2DPanel.(Plot2DPanel.java:47) at Frame1.initialize(Frame1.java:39) at Frame1.(Frame1.java:31) at Frame1$1.run(Frame1.java:18) at java.awt.event.InvocationEvent.dispatch(Unknown Source) at java.awt.EventQueue.dispatchEventImpl(Unknown Source) at java.awt.EventQueue.access$500(Unknown Source) at java.awt.EventQueue$3.run(Unknown Source) at java.awt.EventQueue$3.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source) at java.awt.EventQueue.dispatchEvent(Unknown Source) at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source) at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source) at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source) at java.awt.EventDispatchThread.pumpEvents(Unknown Source) at java.awt.EventDispatchThread.pumpEvents(Unknown Source) at java.awt.EventDispatchThread.run(Unknown Source) Caused by: java.lang.ClassNotFoundException: org.math.io.StringPrintable at java.net.URLClassLoader.findClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) ... 32 more

发生了什么？

编辑

好的。我导入了jmathio.jar。现在我得到了错误:

java.lang.NullPointerException
    at javax.swing.ImageIcon.<init>(Unknown Source)
    at org.math.plot.components.PlotToolBar.<init>(PlotToolBar.java:61)
    at org.math.plot.PlotPanel.addPlotToolBar(PlotPanel.java:149)
    at org.math.plot.PlotPanel.<init>(PlotPanel.java:59)
    at org.math.plot.PlotPanel.<init>(PlotPanel.java:67)
    at org.math.plot.Plot2DPanel.<init>(Plot2DPanel.java:31)
    at Frame1.<init>(Frame1.java:10)
    at Frame1$1.run(Frame1.java:19)
    at java.awt.event.InvocationEvent.dispatch(Unknown Source)
    at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
    at java.awt.EventQueue.access$500(Unknown Source)
    at java.awt.EventQueue$3.run(Unknown Source)
    at java.awt.EventQueue$3.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
    at java.awt.EventQueue.dispatchEvent(Unknown Source)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.run(Unknown Source)

Answer 1

您需要包括 https://github.com/yannrichet/jmathio/blob/master/dist/jmathio.jar jar 在你的类路径中。 jmathplot.jar 依赖于 jmathio.jar。所以下载这个并将其放入您的类路径中，它应该可以工作