Q1. Write a program in JAVA to calculate the area of triangle, circle, square and rectangle. However, you need to ensure that the preceding set of functionalities must be achieved by implementing abstraction.
Solution:
// Java program to illustrate the
// concept of Abstraction
abstract class Shape {
String color;
// these are abstract methods
abstract double area();
public abstract String toString();
// abstract class can have the constructor
public Shape(String color)
{
System.out.println("Shape constructor called");
this.color = color;
}
// this is a concrete method
public String getColor() { return color; }
}
class Circle extends Shape {
double radius;
public Circle(String color, double radius)
{
// calling Shape constructor
super(color);
System.out.println("Circle constructor called");
this.radius = radius;
}
@Override double area()
{
return Math.PI * Math.pow(radius, 2);
}
@Override public String toString()
{
return "Circle color is " + super.getColor()
+ "and area is : " + area();
}
}
class Rectangle extends Shape {
double length;
double width;
public Rectangle(String color, double length,
double width)
{
// calling Shape constructor
super(color);
System.out.println("Rectangle constructor called");
this.length = length;
this.width = width;
}
@Override double area() { return length * width; }
@Override public String toString()
{
return "Rectangle color is " + super.getColor()
+ "and area is : " + area();
}
}
public class Test {
public static void main(String[] args)
{
Shape s1 = new Circle("Red", 2.2);
Shape s2 = new Rectangle("Yellow", 2, 4);
System.out.println(s1.toString());
System.out.println(s2.toString());
}
}
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