Introducing Class Inheritance

When creating a new class in Java, you can define the class to inherit from an existing class. Inheritance is the process by which the new child subclass automatically includes any public or protected primitives, objects, or methods defined in the parent class.

For illustrative purposes, we refer to any class that inherits from another class as a child class, or a descendent of that class. Alternatively, we refer to the class that the child inherits from as the parent class, or an ancestor of the class. If child X inherits from class Y, which in turn inherits from class Z, then X would be considered an indirect child, or descendent, of class Z.

Java supports single inheritance, by which a class may inherit from only one direct parent class. Java also supports multiple levels of inheritance, by which one class may extend another class, which in turn extends another class. You can extend a class any number of times, allowing each descendent to gain access to...