class loader

http://docs.oracle.com/javase/7/docs/technotes/tools/findingclasses.html

https://docs.oracle.com/javase/tutorial/ext/basics/load.html

http://docs.oracle.com/javase/7/docs/technotes/guides/security/spec/security-spec.doc5.html

https://docs.oracle.com/javase/specs/jls/se7/html/jls-4.html

At run time, several reference types with the same binary name may be loaded simultaneously by different class loaders. These types may or may not represent the same type declaration. Even if two such types do represent the same type declaration, they are considered distinct.