Answers to Self-Check Problems - Building Java Programs: A Back to Basics Approach - page 1073

Chapter 9
1. Code reuse is the practice of writing a single piece of code and using it many times
in different programs and contexts. Inheritance is useful for code reuse because it
allows you to write a class that captures common useful code and then extend that
class to add more features and behavior to it.
2. Overloading a method involves creating two methods in the same class that have
the same name but different parameters. Overriding a method involves creating a
new version of an inherited method in a subclass that has identical parameters but
new behavior to replace the old.
3. The following statements are legal:
(a) Vehicle v = new Car();
(b) Vehicle v = new SUV();
(c) Car c = new SUV();
(d) SUV s = new SUV();
4. The this keyword refers to the current object, while the super keyword refers to
the current class's superclass. Use the super keyword when you call a method or
constructor from the superclass that you've overridden, and use the this keyword
when you access your object's other fields, constructors, and methods.
5. UndergraduateStudent can call the setAge method but cannot directly access
the name or age fields from Student .
6. public UndergraduateStudent(String name) {
super(name, 18);
year = 0;
}
7. public void setAge(int age) {
super.setAge(age);
year++;
}
8. B 2
A
A 1
D 2
C
C 1
A 2
A
A 1