Abstract classes and interfaces in Java serve fundamentally different purposes. Learn the differences between these Java language elements and how to use them in your programs. Abstract classes and ...

(See Effective Java, "Prefer interfaces to abstract classes".) With sealed interfaces, library authors no longer have to choose between using polymorphism as an implementation technique, permitting ...

An abstract class is a template definition of methods and variables in a specific class, or category of objects. In programming, objects are units of code, and each object is made into a generic class ...