Unleashing the Power of Java: Comparing Extends and Implements with Real-Life Code Examples

Table of content

  1. Introduction
  2. Understanding Inheritance
  3. Using Extends in Java
  4. Implementing Interfaces
  5. Comparing Extends and Implements
  6. Real-Life Code Examples: Extends
  7. Real-Life Code Examples: Implements
  8. Conclusion


Java is an object-oriented programming language that is widely used for developing software applications. Java supports two key mechanisms for code reuse: extends and implements. The extends keyword is used to create a sub-class from a base class, while the implements keyword is used to implement an interface from a class. In this article, we will explore the differences between these two mechanisms and provide real-life code examples to illustrate their usage.

By leveraging the power of Java's extends and implements keywords, developers can save a lot of time and effort in writing and maintaining their code. They can reuse existing code from base classes and interfaces, and extend their functionality or implement new features as required. This can lead to better code quality, improved productivity, and easier maintenance over time.

In the following sections, we will cover the basics of extends and implements in Java, and show you how they work with some real-world examples. We will also discuss the advantages and disadvantages of each approach, and provide some best practices on how to use them effectively. Whether you are a seasoned Java developer or just starting out, this article will give you a deeper understanding of how to unleash the power of Java to build better software applications.

Understanding Inheritance

Inheritance is a cornerstone of object-oriented programming (OOP) and provides a way for classes to inherit behaviors and properties from other classes. In Java, inheritance is implemented using the extends keyword, which allows a subclass to inherit from a superclass. The subclass inherits all non-private methods and fields of the superclass, which can be used directly in the subclass or overridden to provide specialized behavior.

One of the benefits of inheritance is code reuse, which can lead to more maintainable and modular code. Instead of duplicating code across multiple classes, common behavior can be encapsulated in a superclass and inherited by its subclasses. This allows for changes to be made in one place, rather than having to make the same changes in multiple places.

Another benefit of inheritance is polymorphism, which allows an object of a subclass to be treated as an object of its superclass. This can be useful in situations where a method parameter or return type is of a superclass type, but the actual object passed or returned is a subclass instance. The subclass can still be used in the same way as its superclass, and any overridden methods will be called dynamically at runtime based on the actual type of the object.

Inheritance also provides a way to organize code hierarchically, with more general behavior defined in higher-level classes and more specific behavior defined in lower-level classes. This can make code easier to understand and modify, by providing a clear and logical structure to the class hierarchy.

However, inheritance can also lead to problems such as tight coupling between classes and the potential for the subclass behavior to become tightly coupled to the superclass behavior. Subclasses may also have to override methods they don't need, which can lead to unnecessary code complexity. It is important to use inheritance judiciously and only when it provides real benefits to the codebase.

Using Extends in Java

In Java, the extends keyword is used to create a subclass that inherits properties and methods from a superclass. This allows for code reuse and can simplify the development process by promoting a hierarchical structure within the codebase. When a subclass extends a superclass, it gains access to all of the public and protected member variables and methods of the superclass. The subclass can also add its own member variables and methods, as well as override any methods of the superclass.

Using extends in Java can help improve code readability and maintainability by allowing for logical grouping of related classes. For example, a bank account class could be a superclass, with checking account and savings account classes as its subclasses. This structure allows for common properties and methods, such as deposit and withdrawal, to be defined in the superclass, while still allowing for specialization and customization in the subclasses.

Furthermore, using extends can also promote code reuse and reduce code duplication. By inheriting properties and methods from a superclass, a subclass can avoid re-implementing the same functionality, resulting in fewer lines of code and potentially fewer bugs.

However, it is important to be cautious when using extends in Java. Inheriting from a superclass can also introduce unwanted coupling between classes and lead to maintenance issues. Additionally, applying too many levels of inheritance can result in complex and hard-to-read code. As with any programming technique, it is important to weigh the benefits and drawbacks and consider the specific needs of the project before implementing extends.

Implementing Interfaces

When it comes to in Java, there are several benefits to consider. Interfaces allow for better abstraction and modularization of code, making it easier to update and maintain over time. Additionally, allows for greater flexibility and compatibility with other code, as any class can implement an interface regardless of its inheritance hierarchy.

One real-life example of can be seen in the development of web applications. Let's say we have a web application that needs to make use of multiple external APIs, each with their own unique set of methods and parameters. By creating interface classes that define the required methods for each API, we can then create separate implementing classes that handle the API requests and responses. This allows for better organization and separation of concerns within the codebase, as well as making it easier to swap out or add new APIs as needed.

Another advantage of is that it allows for better testability of code. By using interfaces to define the behavior of a class, we can create mock implementations of those interfaces for testing purposes. This allows us to test the functionality of a class in isolation, without having to worry about external dependencies or complex setup.

Overall, in Java provides a powerful tool for organizing, testing, and maintaining code. By leveraging interfaces and their benefits, developers can create more flexible, scalable, and robust applications.

Comparing Extends and Implements

In object-oriented programming, two concepts are commonly used for creating classes: extends and implements. Extends is used to create a subclass that inherits all the properties of its superclass, whereas implements is used to implement an interface and define its methods. While both these concepts seem similar, they have some fundamental differences.

One major difference between the two is that while extends can only be used for creating a subclass, implements can be used for implementing multiple interfaces. This makes implements a more versatile option for designing classes that need to implement different types of functionality.

Another difference is that extends creates an is-a relationship between the superclass and subclass, whereas implements creates a has-a relationship between the class and the interface. This means that extends is used when creating a new, more specific type of object, while implements is used when adding a new capability to an existing object.

Additionally, extends can override methods or fields of the superclass, whereas implements cannot. This makes extends more suitable for creating customized behavior in a subclass.

In conclusion, both extends and implements have their own specific uses and benefits in object-oriented programming. Which one to use depends on the specific design goals and requirements of the class being created.

Real-Life Code Examples: Extends

Extends is a powerful feature in Java that allows a subclass to inherit properties and methods from a superclass. This inheritance provides a way to reuse code and avoid redundancy. To illustrate this, let's take a look at an example of how Extends can be used in real-life code.

Suppose we have a superclass called Vehicle that contains methods and properties for a generic vehicle. We can create a subclass called Car that Extends the Vehicle class to inherit its properties and methods. In the Car subclass, we can add additional functionality specific to a car, such as a method for turning on the headlights.

public class Vehicle {
  int numOfWheels;
  String color;
  public Vehicle(int numOfWheels, String color) {
    this.numOfWheels = numOfWheels;
    this.color = color;
  public void start() {
    System.out.println("The vehicle has started.");

public class Car extends Vehicle {
  public Car(int numOfWheels, String color) {
    super(numOfWheels, color);
  public void turnOnHeadlights() {
    System.out.println("The headlights are now on.");

In this example, the Car class Extends the Vehicle class and inherits its properties and methods via the super keyword. The Car class also has its own unique method to turn on the headlights. This way, we can create different classes for different types of vehicles and reuse the common properties and methods from the Vehicle class.

Extends provides a powerful way to reuse code and avoid duplication in real-life code scenarios. By leveraging the inheritance provided by Extends, Java developers can enhance the efficiency and effectiveness of their code.

Real-Life Code Examples: Implements

Implements is a commonly used keyword in Java that allows classes to implement interfaces, which define a set of methods and the behavior that implementing classes must adhere to. One example of where implements is utilized in real-life code is in the development of software that uses the Model-View-Controller (MVC) design pattern.

In the MVC pattern, the view and controller classes are responsible for handling the user interface, while the model class manages the data and business logic. To ensure that these components are properly integrated, a common interface is defined, such as the Observer interface.

For instance, consider a simple calculator application where the user enters two numbers, selects an operation, and receives the result. The Model class, responsible for performing the calculations, implements Observer to update the view and controller classes whenever a calculation is complete.

import java.util.Observer;

public class Model implements Observer {
   //methods for performing calculations
   public void update(Observable observable, Object arg) {
       //update view and controller with calculation result

Here, we see that by implementing the Observer interface, the Model class can subscribe to updates from an Observable object and update the view and controller accordingly. This allows for a clear separation of concerns and easier maintenance of the application's codebase.

In addition to the MVC pattern, implements is also commonly utilized in event-driven programming, such as handling button clicks or mouse events. By implementing specific listener interfaces, classes can listen for events and respond accordingly, improving the interactivity and usability of the software.

Overall, implements allows for greater flexibility and modularity in Java code, by providing a means for classes to adhere to a common behavior defined by an interface. Its inclusion in real-life code examples can significantly improve the maintainability, scalability, and functionality of software applications.


In , both the extends and implements keywords serve valuable purposes in Java programming. Extends enables us to create subclasses, allowing us to reuse code and tailor it to our specific needs. Implements, on the other hand, allows us to adhere to interfaces and meet certain specifications. By understanding the differences and capabilities of extends and implements, we can make informed decisions on how to structure our code to create effective and efficient programs.

Real-life code examples provide us with invaluable learning opportunities to see how these concepts play out in practice. Through studying and analyzing code snippets, we can gain a deep understanding of these concepts and hone our abilities to apply them in our own programming projects. Additionally, by keeping up with advancements in technology and development tools, such as pseudocode and LLMs, we can continue to improve our programming skills and stay at the forefront of the field.

I am a driven and diligent DevOps Engineer with demonstrated proficiency in automation and deployment tools, including Jenkins, Docker, Kubernetes, and Ansible. With over 2 years of experience in DevOps and Platform engineering, I specialize in Cloud computing and building infrastructures for Big-Data/Data-Analytics solutions and Cloud Migrations. I am eager to utilize my technical expertise and interpersonal skills in a demanding role and work environment. Additionally, I firmly believe that knowledge is an endless pursuit.

Leave a Reply

Your email address will not be published. Required fields are marked *

Related Posts

Begin typing your search term above and press enter to search. Press ESC to cancel.

Back To Top