I stumbled across a part in the book that confused me for a bit, until I tried it on a few examples. On page 22 in the box "Compiling with wildcards" it says: "However, you cannot use a wildcard to include subdirectories."
It is not correct as such, as you can use
to compile all java files in all subdirectories (one level down only).
Despite the sentence afterwards giving an example, the fact if wildcards cannot be used at all in order to inclue subdirectories still wasn't clear.
I think it can be confusing for someone just starting and learning a few pages earlier that wildcards in import statements are only allowed in the last place. It is easy to assume this might work here the same way.
Do you think rewriting it as "However, you cannot use *.java to include java files in subdirectories" or "However, you cannot use the wildcard in the filename to include java files in subdirectories" would make this part clearer?