正确导入上述类并在其目录中查看它后，为什么会得到ClassNotFoundExpection？ [英] Why am I getting ClassNotFoundExpection when I have properly imported said class and am looking at it in its directory?

问题描述

这是我的Javac编译语句：

This is my Javac compiling statement:

javac -cp
C：\java\code\ j3D\j3dcore.jar; C：\java\code\j3D\j3dutils.jar; C：\java\code\j3D\vecmath.jar
Simple.java

javac -cp "C:\java\code\j3D\j3dcore.jar;C:\java\code\j3D\j3dutils.jar;C:\java\code\j3D\vecmath.jar" Simple.java

• 编译没有问题。



三个jar文件（ j3dcore ， j3dutils 和 vecmath ）是我程序的必需jar（或者至少根据关于J3D的官方教程

The three jar files (j3dcore, j3dutils, and vecmath) are the essential jar's for my program (or at least I am led to believe according to this official tutorial on J3D

为记录起见，我从上面的pdf文件中几乎逐行删除了这段代码。

For the record I ripped this code almost line from line from the above pdf file.



• jar文件正确位于引用位置



当我运行我的 Simple 程序时，（ java Simple ）我得到了

When I run my Simple program, (java Simple) I am greeted with




线程 main j中的异常ava.lang.NoClassDefFoundError：
javax / media / j3d / Cavas3d原因： java.lang.ClassNotFoundExpection：
javax.media.j3d.Canvas3D

当前，我直接盯着位于内的此 Canvas3D.class j3dcore.jar\javax\media\j3d\

Currently I am staring directly at this Canvas3D.class that is located within j3dcore.jar\javax\media\j3d\

wtfisthis.jpg

wtfisthis.jpg

这是源代码：

//First java3D Program
import java.applet.Applet;
import java.awt.BorderLayout;
import java.awt.Frame;
import java.awt.event.*;
import com.sun.j3d.utils.applet.MainFrame;
import com.sun.j3d.utils.universe.*;
import com.sun.j3d.utils.geometry.ColorCube;
import javax.media.j3d.*;
import javax.vecmath.*;
import java.awt.GraphicsConfiguration;

public class Simple extends Applet {
    public Simple() {
        setLayout(new BorderLayout());
        GraphicsConfiguration config = SimpleUniverse.getPreferredConfiguration();
        Canvas3D canvas3D = new Canvas3D(config);
        add("Center", canvas3D);

        BranchGroup scene = createSceneGraph();
        scene.compile();

        // SimpleUniverse is a Convenience Utility class
        SimpleUniverse simpleU = new SimpleUniverse(canvas3D);

        // This moves the ViewPlatform back a bit so the
        // objects in the scene can be viewed.
        simpleU.getViewingPlatform().setNominalViewingTransform();

        simpleU.addBranchGraph(scene);
    }   // end of HelloJava3Da (constructor)
    public BranchGroup createSceneGraph() {
        // Create the root of the branch graph
        BranchGroup objRoot = new BranchGroup();

        // Create a simple shape leaf node, add it to the scene graph.
        // ColorCube is a Convenience Utility class
        objRoot.addChild(new ColorCube(0.4));

        return objRoot;
    }
    public static void main(String args[]){
        Simple world = new Simple();
    }
}







1. 我正确导入了？


2. 我在Javac语句中错误地引用了我的jar文件吗？


3. 如果我清楚地看到了 Canvas3D 在其正确目录内为何java找不到它？


4. j3dcore.jar 和<$ c $的第一个文件夹c> vecmath.jar 是 javax。


5. 如果编译器感到困惑，当在源代码中引用
   时如何指定确切的类？


1. Did I import correctly?
2. Did I incorrectly reference my jar files in my Javac statement?
3. If I clearly see Canvas3D within its correct directory why cant java find it?
4. The first folder in both j3dcore.jar and vecmath.jar is "javax". Is the compiler getting confused?
5. If the compiler is getting confused how do I specify where to find that exact class when referencing it within my source code?




推荐答案

尝试：

java -cp "C:\java\code\j3D\j3dcore.jar;C:\java\code\j3D\j3dutils.jar;C:\java\code\j3D\vecmath.jar"  Simple

您需要在<$ c上包括类路径$ c> java 命令行。

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