[pbhjpbhj]

Doesn't the Java processor tell you in the error message that it "can't find x in classpath" or whatever?

Perhaps the lesson was "read the error message; if it doesn't help then take that as a call to produce useful errors in your own programs"?

[zigzigzag]

Learning to read errors is itself a skill. The number of professional devs who ask questions of the form "I got this message what do I do" and the message itself tells them what to do is astonishing.