abstract class Shape { // Abstract base class that cannot be instantiated directly
    protected String type; // Attribute to store the name/type of the shape
    
    public Shape(String type) { // Constructor for the abstract Shape class
        this.type = type; // Initialize the shape type string
    } // End of constructor
    
    public abstract double area(); // Abstract method with no body; children MUST implement this
    
    public void display() { // Concrete method in an abstract class for shared behavior
        System.out.println("Shape: " + type + " | Area: " + area()); // Print type and calculated area
    } // End of display method
} // End of abstract Shape class

class Circle extends Shape { // Concrete class representing a Circle
    private double radius; // Private attribute for the circle's radius
    
    public Circle(double r) { // Constructor accepting a radius value
        super("Circle"); // Pass type string to the Shape parent constructor
        this.radius = r; // Initialize the radius attribute locally
    } // End of Circle constructor
    
    @Override // Explicitly indicate overriding the abstract area method
    public double area() { // Implementation of area calculation for a circle
        return Math.PI * radius * radius; // Return result using PI and radius squared
    } // End of area implementation
} // End of Circle class

class Rectangle extends Shape { // Concrete class representing a Rectangle
    private double w, h; // Private attributes for width and height
    
    public Rectangle(double w, double h) { // Constructor accepting width and height
        super("Rectangle"); // Pass type string to the Shape parent constructor
        this.w = w; // Initialize width attribute
        this.h = h; // Initialize height attribute
    } // End of Rectangle constructor
    
    @Override // Explicitly indicate overriding the abstract area method
    public double area() { // Implementation of area calculation for a rectangle
        return w * h; // Return result of multiplying width by height
    } // End of area implementation
} // End of Rectangle class

public class PolymorphismLab { // Main class to demonstrate dynamic method dispatch
    public static void main(String[] args) { // Program entry point
        System.out.println("--- Dynamic Method Dispatch Lab ---"); // Print lab header
        
        Shape[] shapes = new Shape[2]; // Create an array of abstract Shape references
        shapes[0] = new Circle(5.0); // Store a Circle object in the first reference slot
        shapes[1] = new Rectangle(4.0, 6.0); // Store a Rectangle object in the second slot
        
        for (Shape s : shapes) { // Iterate through the array using a parent reference
            s.display(); // Call display; Java resolves the correct 'area()' at runtime
        } // End of polymorphic loop
        
        System.out.println("Lab Finished."); // Final log for the polymorphism demo
    } // End of main method
} // End of PolymorphismLab class