Question

(In Java) Inheritance Shapes: Write 5 Classes: 1) Shapes   

2) Triangle

3) Rectangle   

4) Circle

5) TestAllShapes (create 1 object of each type and print the Area for each of them.)

Answer 1

Code:
abstract class Shapes{      //creating an abstract class of shape
    abstract public double getArea();   //creating a abstract method
}

class Rectangle extends Shapes{     //Rectangle class inherites shapes Class

    private double length=0;    //defining length variable
    private double width=0;     //defining length variable
  
    public Rectangle(double l,double w){    //constructor with legth and width as parameters
        this.length = l;    //assignig the values to the variables
        this.width = w;
    }
  
    public double getArea(){        //implementing the abstract function of parent class
        double area = length * width;   // calculating area of rectangle
        return area;    //returning area
    }
}

class Circle extends Shapes{    //Circle extends the Shapes class
  
    private double radius=0;    //defining length variable
    public Circle(double r){    //constructor with radius parameter
        this.radius = r;        //assigning radius
    }
  
    public double getArea(){         //implementing the abstract function of parent class
        double area = Math.PI * radius * radius;       // calculating area of Circle
        return area;    //returning area
    }
}

class Triangle extends Shapes{
  
    private double base = 0;    //defining base variable
    private double height = 0; //defining height variable
  
    public Triangle(double b,double h){     //constructor with legth and width as parameters
        this.base = b;      //assigning base of the triangle
        this.height = h;    //assigning height of the triangle
    }
    public double getArea(){        //area calculating fuction
        double area = 0.5 * base * height;
        return area;        //returning the area
    }
}

public class TestClass{     //test class to print the areas of the objects
    public static void main (String[] args) {
      
        Rectangle rect1 = new Rectangle(2,3);   //creating a rectanle object with legth=2 and width=3
        System.out.println("Area of the Rectangle is :" + " "+rect1.getArea()); //printing the area of the rectangle
      
        Triangle tr1 = new Triangle(2,6);       //creating a Triangle object with base=2 and height=6
        System.out.println("Area of the Triangle is :" + " "+tr1.getArea());     //printing the area of the Triangle
      
        Circle c1 = new Circle(4);          //creating a Circle object with radius 4
        System.out.println("Area of the Circle is :"+ " " + c1.getArea());      //printing the area of the Circle
    }
}