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Issue: When I try to run a java program on my personal machine I recieve the following error: 

Exception in thread "main" java.lang.NoClassDefFoundError: ecs100/UI
    at BallDrop.<init>(BallDrop.java:37)
    at BallDrop.main(BallDrop.java:63)
Caused by: java.lang.ClassNotFoundException: ecs100.UI
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)

Explanation: I am required to write a program using an external library 'ecs100'. It has been supplied as a .jar mime-type file.

I have the file test.java: 

import ecs100.*;
class test{
    public static void main(String args[]){
        System.out.println('Test string');
        UI.initialise(); //this is just how the library is supposed to be used
    }
}

I have tried compiling with the command: javac -cp esc100.jar test.java, which appears to load correctly.

Then when I attempt to run with the command java test it gives the error I specified.

Details: I have been told that the library was written for oracle java 8. I have attempted to compile and run with oracle java 8 JDK, oracle java 9 JDK and openJDK 9 or 8.

I am running ubuntu 16.10. And I do not have any nVidia drivers installed (apparently that can cause problems).

I have tried running files compiled successfully from another computer. Even if they ran on that computer, no luck with mine.

The command java -version outputs:

java version "1.8.0_121" Java(TM) SE Runtime Environment (build 1.8.0_121-b13) Java HotSpot(TM) 64-Bit Server VM (build 25.121-b13, mixed mode)

The command javac -verison outputs:

javac 1.8.0_121

Conclussion: I would greatly appreciate any feedback or suggestions.

I imagine I'm either doing something wrong with:

  • The classpath in compilation
  • The import statement
  • A missing dependancy
  • Wrong use of one of the commands

I am basically positive the problem is not one of the following:

  • An issue with the way I am using the library
Solomon Broadbent
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  • The java tool needs a classpath setup too. That classpath has to include your compiled own classes and that jar file. – GhostCat Mar 16 '17 at 05:37
  • And : before spending 15 minutes to put a question, do some research. And study tutorials /learning materials. – GhostCat Mar 16 '17 at 05:38
  • @GhostCat Sorry. Should I take the question down? – Solomon Broadbent Mar 16 '17 at 05:40
  • Your choice but yes, deleting the question would be appropriate. Just keep in mind that most things you can dream of asking as beginner has been asked here before. – GhostCat Mar 16 '17 at 05:50

0 Answers0