public class Areatest
{ public static void main(String[]args)
{
Figure[]figures={new Triangle(2.0,3.0,3.0),new Rectangle(4.0,6.0),new Square(5.0)};
for(int i=0;i<figures.length;i++)
{ System.out.println("Area of "+figures[i]+" is "+figures[i].getArea());
}
}
}
abstract class Figure
{ public abstract double getArea();
}
class Triangle extends Figure
{ double la,lb,lc;
Triangle(double la,double lb,double lc)
{ this.la=la;this.lb=lb;this.lc=lc;
}
public String toString()
{ return "Triangle: sides are "+la+", "+lb+"& "+lc+":";
}
public double getArea()
{ double s=(la+lb+lc)/2;
return Math.sqrt(s*(s-la)*(s-lb)*(s-lc));
}
}
class Rectangle extends Figure
{ double width,height;
Rectangle(double width,double height)
{ this.width=width;this.height=height;
}
public String toString()
{ return "Rectangle: width= "+width+", height="+height;
}
public double getArea()
{ return width*height;
}
}
class Square extends Figure
{ Square(double width)
{ this.width=width;
}
public String toString()
{ return "Square: width= "+width;
}
public double getArea()
{ return width*width;
}
}