INHERITANCE AND POLYMORPHISM - Introduction to Java Programming - page 420

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11.11

Identify the problems in the following code:

Check

Point

1 public class Circle {
2

private double radius;

3
4 public Circle( double radius) {
5 radius = radius;
6 }
7
8 public double getRadius() {

9 return radius;

10 }
11
12

public double getArea() {

13 return radius * radius * Math.PI;

14 }
15 }
16
17 class B extends Circle {
18 private double length;

19
20 B( double radius, double length) {
21 Circle(radius);
22 length = length;
23 }
24
25 @Override
26

public double getArea() {

27 return getArea() * length;

28 }
29 }

11.12 Explain the difference between method overloading and method overriding.
11.13 If a method in a subclass has the same signature as a method in its superclass with the
same return type, is the method overridden or overloaded?
11.14 If a method in a subclass has the same signature as a method in its superclass with a
different return type, will this be a problem?
11.15 If a method in a subclass has the same name as a method in its superclass with differ-
ent parameter types, is the method overridden or overloaded?
11.16 What is the benefit of using the @Override annotation?

11.6 The Object Class and Its toString() Method
Every class in Java is descended from the java.lang.Object class.

Key
Point

If no inheritance is specified when a class is defined, the superclass of the class is Object by
default. For example, the following two class definitions are the same:

public class ClassName {
...

public class ClassName extends Object {
...

Equivalent

} }

Classes such as String , StringBuilder , Loan , and GeometricObject are implicitly
subclasses of Object (as are all the main classes you have seen in this topic so far). It is