its also difficult to understand ternary operators logic at first sight.

I agree with the first comment, that this is no good practice. And I agree that if-else-if-constructs are also no good practice. But as you can see in the frist solution, the else is not even necessary. The result is very easy to read code. You haven't to be a programmer to understand that code. The point is you don't need to get used to it, but to chained ternary operators you have to.

Thanks for sharing this advice. I was thinking this was a clean way of doing it.

ranks can't be changed

Nesting ternary operators is not a good practice.

This should be 7kyu.

Very clever!

Could be refactored to take advantage of Java 9's map initialization.

Clever, but I don't see how nesting ternary operators is a good practice.

You should always try to find methods, with out withour Google. Is the way to learn!

Love it! Your solution follows my line of thinking but is more streamlined.