6) Develop a JAVA program to create an abstract class Shape with abstract methods
calculateArea() and calculatePerimeter(). Create subclasses Circle and Triangle that
extend the Shape class and implement the respective methods to calculate the area and
perimeter of each shape.
abstract class Shape {
// Abstract method to calculate the area
public abstract double calculateArea();
// Abstract method to calculate the perimeter
public abstract double calculatePerimeter();
class Circle extends Shape {
private double radius;
// Constructor
public Circle(double radius) {
this.radius = radius;
@Override
public double calculateArea() {
return Math.PI * radius * radius;
@Override
public double calculatePerimeter() {
return 2 * Math.PI * radius;
class Triangle extends Shape {
private double side1;
private double side2;
private double side3;
// Constructor
public Triangle(double side1, double side2, double side3) {
this.side1 = side1;
this.side2 = side2;
this.side3 = side3;
@Override
public double calculateArea() {
// Using Heron's formula to calculate the area of a triangle
double s = (side1 + side2 + side3) / 2.0;
return Math.sqrt(s * (s - side1) * (s - side2) * (s - side3));
@Override
public double calculatePerimeter() {
return side1 + side2 + side3;
public class Main {
public static void main(String[] args) {
Circle circle = new Circle(5.0);
System.out.println("Circle - Area: " + circle.calculateArea());
System.out.println("Circle - Perimeter: " + circle.calculatePerimeter());
Triangle triangle = new Triangle(3.0, 4.0, 5.0);
System.out.println("Triangle - Area: " + triangle.calculateArea());
System.out.println("Triangle - Perimeter: " + triangle.calculatePerimeter());
