Page 259 - ComputerScience_Class_11

The output of the preceding program is as follows:

BlueJ: Terminal Window - Java
Options

The Area of a Circle: 98.53311999999998
The Area of a Rectangle: 10
The Area of a Square: 25

In the above program, there are three methods:
• area(double r) and area(int s) have one parameter each but the type of parameters are different.
• area(int s) and area(int l, int b) have the same type of parameters but the number of parameters is different.

Thus, method overloading is the process of defining multiple methods with the same name, but with different parameter
types or different numbers of parameters. This is a form of polymorphism. In the case of method overloading, it
is a type of compile-time polymorphism (also known as static polymorphism), where the method to be invoked is
determined by the compiler based on the method signature and the arguments provided. The compiler finds the best
match for the method call at compile-time, which is called static binding.

9.9 OBJECTS AND CLASSES
An object is the most fundamental unit of object-oriented programming. It is a real-life entity and is an instance of a
class. Objects have properties that define them, as well as functions and methods associated with them.
A class on the other hand is a logical entity and consists of the characteristics and behaviour which are common to all
the objects in that class.
Classes, thus act as a blueprint for creating objects of the same type. They are non-primitive data types that are
created by the user as and when required.
For example, if we consider a class named Books, then the different objects in the class can be Story books,
Comic books, Workbooks and so on. Each of these different objects has the general characteristics of the books (as they
get it from the class Books) and yet are different with their own attributes like genre type, author, year of publication,
etc.

9.9.1 Creation of an Object of a Class
The syntax of creating an object of a class is:

[class_name] [object_name] = new [constructor with or without parameter];
For example,

Factorial ob = new Factorial ();
Let us define a class:

class factorial
{
int n, f;
factorial (int temp)
{
n=temp;
f=1;
}
private void calculate ()
{
int i;
for (i=1; i<=n;i++)
{

Methods and Constructors 257