shapearea.java

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abstract class Shape{
  double x,y,area;
  public abstract void calcArea();
  public void showArea(){System.out.println("Area="+area);}
}
class Circle extends Shape{
  public Circle(int r) {x=r;}
  public void calcArea(){area=3.14*x*x;}
}
class Square extends Shape{
  public Square(int l) {x=y=l;}
  public void calcArea(){area=x*y;}
}

public class ShapeArea{
  public static void main(String args[]){
    Shape s;
    s = new Circle(10); s.calcArea(); s.showArea();
    s = new Square(10); s.calcArea(); s.showArea();
  }
}