Lab 21
AIM: Describe abstract class called Shape which has three subclasses say Triangle, Rectangle, Circle. Define one method area() in the abstract class and override this area() in these three subclasses to calculate for specific object i.e. area() of Triangle subclass should calculate area of triangle etc. Same for Rectangle and Circle.

AbstractClassEx.java
```abstract class Shape
{
float dim1,dim2,radius;
abstract float area();
}
class Triangle extends Shape
{
Triangle(float d1, float d2)
{
dim1=d1;
dim2=d2;
}
float area()
{
System.out.println("Area of Triangle is ");
return (dim1*dim2)/2;
}
}
class Rectangle extends Shape
{
Rectangle(float d1, float d2)
{
dim1=d1;
dim2=d2;
}
float area()
{
System.out.println("Area of Rectangle is ");
return dim1*dim2;
}
}
class Circle extends Shape
{
Circle(float d1)
{
radius=d1;
}
float area()
{
System.out.println("Area of Circle is ");
return 3.14f*radius*radius;
}
}
class AbstractClassEx
{
public static void main(String arg[])
{
Triangle t=new Triangle(4.3f,5.3f);
Rectangle r=new Rectangle(2.4f,4.2f);
Circle c=new Circle(10.5f);

System.out.println(t.area());
System.out.println(r.area());
System.out.println(c.area());

}
}
```

Output
 Abstract class in java by practical server

Happy Coding :)