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.

Examples with abstract classes and methods; ... Shape.java, Rectangle.java, and Circle.java) are located in the current directory, compile them via either of the following command lines: ...

The release of Java SE 15 in Sept 2020 will introduce "sealed classes" (JEP 360) as a preview feature. A sealed class is a class or interface which restricts which other classes or interfaces may ...

However, seasoned Java developers know that sometimes the simplest of language constructs can turn out to be the most powerful, as is the case with object models designed with abstract classes and ...