Java, A Beginner's Guide, 5th Edition, 5th Edition

Constructors and Inheritance

In a hierarchy, it is possible for both superclasses and subclasses to have their own constructors. This raises an important question: What constructor is responsible for building an object of the subclass—the one in the superclass, the one in the subclass, or both? The answer is this: The constructor for the superclass constructs the superclass portion of the object, and the constructor for the subclass constructs the subclass part. This makes sense because the superclass has no knowledge of or access to any element in a subclass. Thus, their construction must be separate. The preceding examples have relied upon the default constructors created automatically by Java, so this was not an issue. However, in practice, ...