Java Inheritance Programming - Java Program to Demonstrate Method Overriding with Shape and Rectangle

// Define the parent class Shape
public class Shape {
    // Define a public method named getArea that returns a double
    public double getArea() {
        // Return 0.0 as the default area
        return 0.0;
    }
} 

// Define the child class Rectangle that extends Shape
public class Rectangle extends Shape {
    // Define private instance variables length and width
    private double length;
    private double width;
    
    // Define the constructor that takes length and width as parameters
    public Rectangle(double length, double width) {
        // Assign the length parameter to the instance variable length
        this.length = length;
        // Assign the width parameter to the instance variable width
        this.width = width;
    }
    
    // Use the @Override annotation to indicate that this method overrides a method in the superclass
    @Override
    // Define the getArea method that returns a double
    public double getArea() {
        // Return the area of the rectangle (length * width)
        return length * width;
    }
} 

// Define the main class
public class Main {
    // Define the main method
    public static void main(String[] args) {
        // Create an instance of Rectangle with length 3.0 and width 10.0
        Rectangle rectangle = new Rectangle(3.0, 10.0);
        // Call the getArea method on the rectangle instance and store the result in the area variable
        double area = rectangle.getArea();
        // Print the area of the rectangle to the console
        System.out.println("The area of the rectangle is: " + area);
    }
}