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.

Most introductory Java texts take an implementation-centric stab at how to use interfaces and abstract classes. However, few provide a clear design distinction for choosing between these two ...

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 ...

public final class StockTransaction extends Transaction { } How sealed classes work. The key concept with sealed classes is that they are declared using the sealed keyword, followed by the permits ...