Why need interfaces in java?
6853
Interface vs Abstract Class (general OO)
21739
When to use abstract classes?
22329
Why do I need an Interface for Covariance (out Type)?
146553
Why an interface can not implement another interface?
100925
Does an interface by default extend Object?
150146
Final arguments in interface methods - what's the point?
139818
Why implement interface explicitly?
80510
Implements vs extends: When to use? What's the difference?
42596
Why would a static nested interface be used in Java?
15691
Interface vs Base class
33679
Why should the interface for a Java class be preferred?
31188
In Java when one interface extends another, why would one redeclare a method in a subinterface?
69939
Implement an interface and override methods in Java?
137841
Private Interfaces
66575
Why use an interface in Apex?
848
Why can't I define a static method in a Java interface?
149611
Java: Why are wrapper classes needed?