Question

Create a base class called Shape, it contain two methods getxyvalue() and showxyvalue() for accepting co-ordinates and to displaying the same. Create a subclass called Rectangle. It also contains a method to display the length and breadth of the rectangle called showxyvalue(). Use the overriding concept.

Short answer

Create a 'Shape' class with methods for coordinates, then a 'Rectangle' subclass that overrides 'showxyvalue()' to include length and breadth.

Step-by-step solution

Define the Base Class 'Shape'

Begin by defining a base class called 'Shape'. This class will contain two methods: 'getxyvalue()' and 'showxyvalue()'. The 'getxyvalue()' method will accept the x and y coordinates, while 'showxyvalue()' will display these coordinates.

Implement the Method 'getxyvalue()'

Inside the 'Shape' class, implement the 'getxyvalue()' method. This method should take two parameters, x and y. These will be stored as instance variables to represent the coordinates of the shape.

Implement the Method 'showxyvalue()' for 'Shape'

In the 'Shape' class, implement the 'showxyvalue()' method. This method should print out the coordinates stored in the instance variables. Use a print statement to display the x and y values.

Define the Subclass 'Rectangle'

Create a subclass called 'Rectangle' which inherits from the 'Shape' class. This subclass will add new functionality specific to a rectangle while using existing methods from the 'Shape' class.

Override the Method 'showxyvalue()' in 'Rectangle'

Override the 'showxyvalue()' method in the 'Rectangle' class. This overridden method will display a message indicating it is displaying the rectangle, and show the same coordinates as in the base class, along with a possible message about the rectangle's properties like length and breadth.

Implement a Method for Rectangle's Dimensions

In the 'Rectangle' class, create additional attributes or methods to store and display the rectangle's length and breadth. Ensure that these are also displayed in the overridden 'showxyvalue()' method.

Key concepts

Inheritance

Inheritance is a core concept in object-oriented programming (OOP) that allows a class, known as a child class or subclass, to adopt properties and methods from another class, called a parent class or superclass. This concept is akin to the real world where children can inherit certain traits or behaviors from their parents. In the context of programming, inheritance promotes reusability and organization by allowing developers to create new classes on top of existing ones, reducing the need for redundant code.

In our example, we've defined the 'Shape' class, which serves as the parent class. It contains two methods: 'getxyvalue()', which accepts x and y coordinates, and 'showxyvalue()', which displays these coordinates. When we create the 'Rectangle' class, it inherits from 'Shape'. This means that 'Rectangle' automatically has access to the methods 'getxyvalue()' and 'showxyvalue()' without needing to redefine them. However, 'Rectangle' can add its own unique methods or modify inherited ones through other OOP principles like polymorphism and method overriding.

Polymorphism

Polymorphism is a feature of OOP that allows objects to be treated as instances of their parent class rather than their actual class. The term polymorphism is derived from Greek, meaning "many forms." In practice, this means that a single interface can be used to represent different data types or classes. This capability enhances flexibility and integration within a program.

In our case, when a method like 'showxyvalue()' is called on an object, the program inherently knows, at runtime, which specific version of the method to execute based on the object's class. Thus, if a 'Rectangle' object is created, its version of 'showxyvalue()' will be called, demonstrating polymorphism. Polymorphism allows us to write more generic code, which works seamlessly across various classes, enhancing maintainability and scalability.

Method Overriding

Method overriding is an essential feature of OOP that allows a subclass to provide a specific implementation of a method that is already defined in its superclass. This is crucial when the subclass requires slightly different behavior from that of the parent class. In our exercise, the 'showxyvalue()' method in the 'Shape' class is overridden in the 'Rectangle' class. In the base class 'Shape', 'showxyvalue()' displays the x and y coordinates. However, 'Rectangle' provides its version of 'showxyvalue()', which may display additional information specific to rectangles, such as their length and breadth. This example illustrates how method overriding gives more control and flexibility to subclasses to behave as needed, while still maintaining a consistent interface through inheritance.

Class Design

Class design is a process in OOP that involves organizing and structuring classes in a way that maximizes code efficiency, readability, and maintainability. A well-designed class should encapsulate its data and related functions, providing a clear and intuitive interface for the rest of the program. In our task, the design begins with the simple, general-purpose 'Shape' class, which contains properties and methods relevant to all shapes, such as handling coordinates with 'getxyvalue()' and 'showxyvalue()'. By creating a separate 'Rectangle' subclass that inherits from 'Shape', we follow the principle of coding with specialization in mind. The 'Rectangle' class adds unique properties such as length and breadth, keeping the implementation specific to rectangles while utilizing inherited features from 'Shape'. Good class design ensures that changes in one part of the system cause minimal impact elsewhere, encouraging scalability and adaptability to new requirements. It employs encapsulation, inheritance, and polymorphism effectively to create a robust system architecture.