/*
Program 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.
*/
package p6;
//Abstract class
abstract class Shape {
double calculateArea () {
return -1;
}
double calculatePerimeter () {
return -1;
}
}
//class Circle
class Circle extends Shape {
int r;
Circle () {r = 10; }
Circle (int r) {this.r = r; }
double calculateArea () {
System.out.println("Cirle class: calculateArea() called.");
return 3.14 * r * r; //pi * r * r
}
double calculatePerimeter() {
System.out.println("Cirle class: calculatePerimeter() called.");
return 2 * 3.14 * r; //2 * pi * r
}
}
//class Triangle
class Triangle extends Shape {
int a, b, c;
int p;
Triangle () {a = b = c = 10; }
Triangle (int a, int b, int c) {
this.a = a;
this.b = b;
this.c = c;
}
double calculateArea () {
System.out.println("Triangle class: calculateArea() called.");
p = a + b + c; //perimeter
double s = p/2; //semi-perimeter = perimeter/2
//Heron's Formula
double area = Math.sqrt(s * (s-a) * (s-b) * (s-c));
return area;
}
double calculatePerimeter () {
Perimeter = sum of all sides (a + b + c)
System.out.println("Triangle class: calculatePerimeter () called.");
return (a + b + c);
}
}
public class AbstractDemo {
public static void main(String[] args) {
Shape s;
Circle c = new Circle ();
Triangle t = new Triangle();
//Circle object
s = c;
System.out.printf("Circle Area: %5.2f \n\n", s.calculateArea());
System.out.printf("Circle Perimeter: %5.2f \n\n", s.calculatePerimeter());
//Triangle object
s = t;
System.out.printf("Triangle Area : %5.2f \n\n", s.calculateArea() );
System.out.printf("Triangle Perimeter: %5.2f \n\n", s.calculatePerimeter());
} //end main
} //end InheritenceDemo
Output: java
