It’s a good idea to use an abstract class when you need to implement mutable state. As an example, the Java Collections Framework includes the AbstractList class, which uses the state of variables.

The purpose of an abstract class is to function as a base for subclasses. This Java abstract class tutorial explains how abstract classes are created in Java, what rules apply to them. This tutorial ...

A recurring request asks to see a complete example of using interfaces and abstract classes. Based on the feedback, the original answer proved a bit too theoretical, so in this follow-up Java Q&A ...

That means you cannot create new instances of an abstract class. It works as a base for subclasses. You should learn about Java Inheritance before attempting this challenge. Following is an example of ...

Interfaces, however, support multiple inheritances where abstract classes don't. Implementation is done similarly in Java. For example, using the keyword implements will make a Java interface, while ...