Answer 1

File names will generally match the name of the only public class/interface etc within the file.

I.E. Program.java would have a public class Program {}. It may have other classes in the file, but they are usually private, protected, default, or sub classes.

http://beginwithjava.blogspot.com/2011/01/javas-file-names-and-class-names.html?m=1
http://www.oracle.com/technetwork/java/codeconventions-135099.html