Hi @Werner Stinckens​ , Yes i followed the same instructions and was trying to solve this with a java program then later planning to convert python script to a jar file.

Below is the program that i used , Using Eclipse i was able to generate the .jar file successfully by adding "org.apache.hadoop.hive.ql.exec.UDF" this class related jar into the project,

Code :

import org.apache.hadoop.hive.ql.exec.UDF;

public class SimpleUdf extends UDF {

public int evaluate(int value) {

return value + 10;

}

}

Jar file Link :

http://www.java2s.com/Code/Jar/h/Downloadhive041jar.htm

And then tried the below commands

%sql

CREATE FUNCTION simple_udf AS 'SimpleUdf'

  USING JAR '/tmp/SimpleUdf.jar';

AND

%sql

CREATE FUNCTION simple_udf AS 'SimpleUdf'

  USING JAR '/dbfs/tmp/SimpleUdf.jar';

%sql

select simple_udf(2)

I placed it on the File Store of data bricks cluster and it kept throwing the same error, please make sure the class path is correct.