pure abstract class and interface [duplicate]

Answer 1

It's not a very theorotical explaination but, programatically it's all correct

                                    Interface                   Abstract Class
Extend Class                            No                          Yes
Extend Abstract Class                   No                          Yes
Implement Interface                     Yes(Extend Interface)       Yes
Variables                               Public Static Final         Public/Protected/Private/static/final/transient/volatile
Contain Non-Public Method               No                          Public/Protected/*Private
Contain Abstract Method                 Yes                         Yes
Contain No-Body, Non-Abstract Method    Yes                         No
Contain Defined Method                  No                          Yes
Contain Main Method                     No                          Yes

*Abstract classes can have private methods, but not abstract private methods.