Inheritance - Java Software Solutions: Foundations of Program Design - page 466

LISTING 9.12

//********************************************************************
// Pizza.java Author: Lewis/Loftus
//
// Represents a pizza, which is a food item. Used to demonstrate
// indirect referencing through inheritance.
//********************************************************************

public class Pizza extends FoodItem
{
//-----------------------------------------------------------------
// Sets up a pizza with the specified amount of fat (assumes
// eight servings).
//-----------------------------------------------------------------
public Pizza ( int fatGrams)
{
super (fatGrams, 8);
}
}

Even though the Pizza class cannot explicitly reference calories , fatGrams , or
CALORIES_PER_GRAM , they are available for use indirectly when the Pizza object
needs them. A Pizza object cannot be used to invoke the calories method, but
it can call a method that can. Note that a FoodItem object was never created or
needed.

SELF-REVIEW QUESTIONS (see answers in Appendix N)
SR 9.16 Are all members of a parent class inherited by the child? Explain.
SR 9.17 Could the Pizza class refer to the variable servings explicitly? What
about the calories method? Explain.

9.5 Designing for Inheritance

As a major characteristic of object-oriented software, inheritance
must be carefully and specifically addressed during software design.
A little thought about inheritance relationships can lead to a far
more elegant design, which pays huge dividends in the long term.

KEY CONCEPT
Software design must carefully and
specifically address inheritance.