Hi, i import json-simple into by: implementation group: ‘com.googlecode.json-simple’, name: ‘json-simple’, version: ‘1.1.1’ . I can see the library at intellij, i can build it in intellij, i can run it. When i am running jar file from command line i get an error message that classes inside that projetc not found?

Take a look at the Application Plugin. It includes a run task which will setup the classpath correctly (including your jar plus any dependent jars).