Question

This program compiles and runs swimmingly in eclipse on the same machine, but I’d really like to work from the command line and my editor of choice.

CollectNewspaperKarel.java

import stanford.karel.*;

    public class CollectNewspaperKarel extends SuperKarel {

        public void run() {
            // You fill in this part
        }

    }

The karel.jar is in the same directory as the file above.

Compile

javac -cp karel.jar CollectNewspaperKarel.java

with no errors.

Run

java -cp karel.jar CollectNewspaperKarel

Exception in thread "main" java.lang.NoClassDefFoundError: CollectNewspaperKarel
Caused by: java.lang.ClassNotFoundException: CollectNewspaperKarel
    at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:247)

Answer 1

you forgot to include your class to classpath when running the program.

Try this – if running on windows:

java -cp karel.jar;CollectNewspaperKarel.class CollectNewspaperKarel

or this if you’re running on linux:

java -cp karel.jar:CollectNewspaperKarel.class CollectNewspaperKarel

One more thing however, you need to have main method in your class, otherwise it won’t work 🙂

Update:

I’ve found following site: http://ycsoftware.net/setting-up-karel-the-robot-in-eclipse/

seems, you should go with the following arguments if you have the same version of karel as the author there:

on windows:

java -cp karel.jar;CollectNewspaperKarel.class stanford.karel.Karel code=CollectNewspaperKarel

on linux:

java -cp karel.jar:CollectNewspaperKarel.class stanford.karel.Karel code=CollectNewspaperKarel