我剛開始用jmathplot和我得到這個異常消息

Question

我想在我的應用繪製一個圖所以我下載jmathplot.jar，並把它添加到我的項目。

當我添加一個字段到我的框架：

private PlotPanel plot = new Plot2DPanel(); 

我在編譯得到一個討厭的長異常消息：

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

這是怎麼回事？

編輯

確定。我導入了jmathio.jar。現在，我得到了錯誤：

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

你需要在你的classpath https://github.com/yannrichet/jmathio/blob/master/dist/jmathio.jar罐子。 jmathplot.jar取決於jmathio.jar。所以請下載並將其放入你的classpath並且它應該可以工作