Question

public class RunScript {
    public static void main(String[] args) {
        System.out.println("Hello World");
    }
}

I created a Java project and a package called com.klong

Inside of the package I have one .java file with the above code in it.
I export it into a runnable jar file. Then I try to run the jar in a command line using this:
java test.jar

When I try that, I get the following error

C:\Users\IBM_ADMIN\Tracing stuff>java test.jar
Exception in thread "main" java.lang.NoClassDefFoundError: test.jar
Caused by: java.lang.ClassNotFoundException: test.jar
    at java.net.URLClassLoader.findClass(URLClassLoader.java:434)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:653)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:358)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:619)
Could not find the main class: test.jar.  Program will exit.

I’ve tinkered with exporting into a normal jar file and such. I’ve looked at other questions about this error. I’ve tried using commands such as set classpath=BLEH

This project is as simple as can be so hopefully you can help me figure out this pesky error!

Answer 1

You need to run java -jar test.jar, what you’re currently doing is asking java to look for compiled classes with the name test.jar.