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.

Fork this repo. Clone this repo. Add your instructor and the class graders as collaborators to your repository. If you are unsure who your class graders are, ask your instructor or refer to the day 1 ...

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 ...

Readers have returned quite a bit of feedback concerning, “Abstract Classes Vs. Interfaces” from April 2001. A recurring request asks to see a complete example of using interfaces and abstract ...

The Positional Shape Hierarchy: Let's now deal with a more complicated example of a positional shape inheritance hierarchy. It is illustrated below graphically; the superscript A is used to denote ...

For example, using the keyword implements will make a Java interface, while the keyword extends makes an abstract class. Abstraction vs. encapsulation Encapsulation in object-oriented programming is ...

Sealed classes make Java an even more powerful and expressive language and set the stage for even more sophisticated techniques such as pattern matching, which we'll explore in a subsequent article. A ...