Java ClassPath with java.lang.NoClassDefFoundError

Question

I'm working on a java project and trying to run a jar file. I'm getting the error:

Exception in thread "main" java.lang.NoClassDefFoundError

Most of the other threads I've read, said that it was because I needed to use the -classpath option. However, I've tried implementing this a couple of ways and I'm getting the same error, still.

The last way that I tried to implement the -classpath option and execute the jar file is shown below.

java -classpath "/full/file/path/file.jar" -jar file.jar 

Please let me know what I'm doing wrong!

Answer 1

-jar is for self-contained jars. https://stackoverflow.com/a/18413058/20394 explains that -classpath is ignored when -jar is specified. Just do -jar /full/file/path/file.jar if it is a self-contained jar. If it's not, you will need to use -classpath and make sure all its runtime dependencies are available via that classpath.

If you haven't already, it might be worth learning to use a build system like mvn or bazel to manage the class path for you, or to try running your class through an IDE like Eclipse.