Java Program to Find out the Area and Perimeter of Rectangle using Class Concept

Java Language is one of the most used popular object - oriented programming language in present world. Class concept is one of the most important feature in Object - oriented languages. A Class is a like a blue print of an object. For example, when we want to build a house we first create a blue print of the house in other words we create a plan showing how we are going to build the house. Based on the plan we can create a number of houses. Similarly using class, we can create a number of objects. A class is a blueprint for creating a number of objects where objects are the real world entities like car, bike, pen etc. A class has all the characteristics of an object and objects has values for those characteristics. In this article, we are going to write a java program to find the perimeter and area of a rectangle using class concept.

A Class consists of the following ?

• Data Members ? Data Members represent the characteristics/properties of a collection of objects

• Methods ? Methods represents the actions performed by an object.

For an example, if we consider a person as a class, then the properties like name, age, address are the data members and the actions performed by a person like sit, stand, eat, walk are the methods of the class.

Syntax to create a class

class ClassName
{
   //data members
   //methods
}

ClassName always starts with a capital letter. For example, Person, House, Bank, etc.

Example

class Person{
   //data members
   String name;
   int age;
   String city;
   //methods
   void read(){
      System.out.println("Reading");
   }
}

Syntax to create an object

ClassName objectname = new ClassName();

Example

Person person_one =new Person();

Perimeter of a rectangle

The perimeter of a rectangle is the total area covered by the sides of the rectangle, which is the area covered by the length and width of the rectangle.

Formula

Perimeter of the rectangle 
= area covered by the sides of the rectangle
= 2(l+w)
where,  l : length of rectangle
        w : width of rectangle

Area of a rectangle

Area of a rectangle is the total space occupied by the rectangle in a 2-d plane.

Formula

Area of the rectangle 
= area covered by the rectangle
=  l*w
where , l : length of rectangle
             w : width of rectangle

Algorithm

STEP 1 ? Create a custom class name Rectangle which has "area()" and "perimeter()" methods. These functions give us the area of the Rectangle and the Perimeter of a rectangle as output.

STEP 2 ? Now, in the main class create an Object of the rectangle using the constructor.

STEP 3 ? Now call the respective functions to find the area of rectangle and perimeter of rectangle using the created Object.

Example

In this example, we create a custom Rectangle class which has "area()" and "perimeter()" methods. We then create an object of Rectangle class in main class using a constructor of main class and call respective methods area() and perimeter() on the created object. Once, the methods are called they are executed and the output is printed

// Java program to calculate  the area and perimeter of a rectangle using class concept
import java.util.*;
// Rectangle Class File
class Rectangle {
    // data members
    int length, width;
    // methods
    //constructor to create Object
    Rectangle(int length, int width) {
        this. length = length;
        this.width = width;
    }
    // prints the area of rectangle
    public void area() {
        int areaOfRectangle;
        areaOfRectangle = this.length * this.width;
        System.out.println("Area of rectangle with the given input is : " + areaOfRectangle);
    }
    // prints the perimeter of rectangle
    public void perimeter() {
        int  perimeterOfRectangle;
        perimeterOfRectangle = 2 * (this.length + this.width);
        System.out.println("Perimeter of rectangle with the given input is : " + perimeterOfRectangle);
    }
}
public class Main {
    public static void main(String args[]) {
        Rectangle rect_obj = new Rectangle(10,5);  // obect creation
        System.out.println("Length = " + rect_obj.length);
        System.out.println("Width = " + rect_obj.width);
        rect_obj.area(); // returns area of rectangle
        rect_obj.perimeter(); //returns perimeter of rectangle
    }
}

Output

Length = 10
Width = 5
Area of rectangle with the given input is : 50
Perimeter of rectangle with the given input is : 30

Time Complexity: O(1) Auxiliary Space: O(1)

Thus in this article, we have learnt how to implement java code to find the area and perimeter of a rectangle using Class concept.