About Java.lang.NoClassDefFoundError

Workaround 1:

Check to see if a third-party jar package is being directed into build path, you should make sure that both Lib and referenced libraries

Method: Copy the jar package into LIB, add to build path separately, then set Lib as source folder

Workaround 2:

To see if the jar package export process is correct, be sure to export the runnable jar file, not just the jar file

This article is about the difference between the jar file and the runnable jar file in eclipse

About Java.lang.NoClassDefFoundError