What is an Abstract Class? An abstract class is a class that is declared abstract —it may or may not include abstract methods. Abstract classes cannot be instantiated, but they can be subclassed. An ...

When developing framework and reusable code, we need to develop classes that are partially abstract with partial implementation. Protocol and protocol extensions provide this, but they cannot have ...

Nested classes are classes that are declared as members of other classes or scopes. Nesting classes is one way to better organize your code. For example, say you have a non-nested class (also known as ...

Learn the four types of polymorphism in Java, then start using subtype polymorphism to execute different forms of the same Java method. Polymorphism refers to the ability of some entities to occur in ...