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.

Sealed classes in Java let developers limit the creation and use of subclasses and preserve the class hierarchy. Here is how sealed classes in Java work.

A tutorial highlighting the various design patterns in Java. Learn about the benefits and different types of design patterns.

The Design by Contract technique stresses the importance of explicitly specifying the constraints that hold before and after a software component executes.