The error I encountered in today's study was the most unexpected error I've ever had, so I'll record it so I don't forget it.
Class name is described in upper camel case </ font>.
Upper camelcase: Capitalize the first word and the first letter of the word break. Camelcase: Start with a lowercase letter and capitalize the first letter of the word break. Snake case: Connect words with underscores (_).
Class name → Upper camel case Variable name / method name → Snake case
In today's learning, no matter how many times I looked back at the processing description, I couldn't find any difference, and I wrote the class name with the words connected in a snake case, and I got an error that the class could not be read. By the way, camel is a camel. The capital letters are bumps. Does the underscore look like a snake?