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.

A method might accept a specific type and its subclasses, but you want to restrict usage to a select few implementations of your own design. Java's open inheritance model can feel like an open ...

However, there are collection classes in Java that act like a Java array but resize themselves automatically. Any class that extends the List interface expands dynamically. Java arrays do not expand ...