About Question enthuware.ocpjp.v8.2.1277 :

[karlose2006]

Class A should be public for compile

[admin]

Not really. It is ok to have a non-public class in a file. You might want to try compiling it to confirm.

The rule is that a public class must be in a file by the same name. So, if class A were public, then it had to be in A.java file.