//***************************************************
//   Example of Method Overriding
//      Uses dynamic method dispatch.
//***************************************************
class TwoDShape {  
  private double width;  
  private double height;  
  private String name;  
  
  // A default constructor.  
  TwoDShape() {  
    width = height = 0.0;  
    name = "none";  
  }  
  
  // Parameterized constructor.  
  TwoDShape(double w, double h, String n) {  
    width = w;  
    height = h;  
    name = n;  
  }  
  
  // Construct object with equal width and height.  
  TwoDShape(double x, String n) {  
    width = height = x;  
    name = n;  
  }  
  
  // Construct an object from an object.  
  TwoDShape(TwoDShape ob) {  
    width = ob.width;  
    height = ob.height;  
    name = ob.name;  
  }  
  
  // Accessor methods for width and height.  
  double getWidth() { return width; }  
  double getHeight() { return height; }  
  void setWidth(double w) { width = w; }  
  void setHeight(double h) { height = h; }  
  
  String getName() { return name; }  
  
  void showDim() {  
    System.out.println("Width and height are " +  
                       width + " and " + height);  
  }  
  
  double area() {   
    System.out.println("area() must be overridden");  
    return 0.0;  
  }   
}  
  
// A subclass of TwoDShape for triangles. 
class Triangle extends TwoDShape {  
  private String style;  
    
  // A default constructor.  
  Triangle() {  
    super();  
    style = "none";  
  }  
  
  // Constructor for Triangle.  
  Triangle(String s, double w, double h) {  
    super(w, h, "triangle");  
  
    style = s;   
  }  
  
  // One argument constructor. 
  Triangle(double x) {  
    super(x, "triangle"); // call superclass constructor  
  
    style = "filled";   
  }  
  
  // Construct an object from an object.  
  Triangle(Triangle ob) {  
    super(ob); // pass object to TwoDShape constructor  
    style = ob.style;  
  }  
  
  // Override area() for Triangle. 
  double area() {  
    return getWidth() * getHeight() / 2;  
  }  
  
  void showStyle() {  
    System.out.println("Triangle is " + style);  
  }  
}  
  
// A subclass of TwoDShape for rectangles.   
class Rectangle extends TwoDShape {   
  // A default constructor.  
  Rectangle() {  
    super();  
  }  
  
  // Constructor for Rectangle.  
  Rectangle(double w, double h) {  
    super(w, h, "rectangle"); // call superclass constructor  
  }  
  
  // Construct a square.  
  Rectangle(double x) {  
    super(x, "rectangle"); // call superclass constructor  
  }  
  
  // Construct an object from an object.  
  Rectangle(Rectangle ob) {  
    super(ob); // pass object to TwoDShape constructor  
  }  
  
  boolean isSquare() {   
    if(getWidth() == getHeight()) return true;   
    return false;   
  }   
     
  // Override area() for Rectangle. 
  double area() {   
    return getWidth() * getHeight();   
  }   
}  
  
class DynShapes {  
  public static void main(String args[]) {  
    TwoDShape shapes[] = new TwoDShape[5];  
  
    shapes[0] = new Triangle("outlined", 8.0, 12.0);  
    shapes[1] = new Rectangle(10);  
    shapes[2] = new Rectangle(10, 4);  
    shapes[3] = new Triangle(7.0);  
    shapes[4] = new TwoDShape(10, 20, "generic"); 
  
    for(int i=0; i < shapes.length; i++) {  
      System.out.println("object is " + shapes[i].getName());  
      System.out.println("Area is " + shapes[i].area());  
  
      System.out.println();    
    }  
  }  
}