In general, Design Patterns refer to a collection of standard solutions for common issues encountered in Object-Oriented Software Development. These solutions are well-established and have been formulated over the years through trial and error by seasoned software developers.
It’s crucial to recognise that these solutions aren’t just fixed answers to problems but rather templates that can be adapted based on the specific issues you’re addressing. Each design pattern serves as a foundational plan that can be applied to resolve design problems and can be integrated into any software module during various stages of development. They represent language-independent strategies that enable you to create flexible, maintainable, and reusable code.
Why Are Design Patterns in Java Needed?
Design Patterns are an integral part of the vocabulary of seasoned Software Developers, serving as go-to solutions for general design problems. In the context of Java, understanding Design Patterns becomes crucial as Java itself incorporates these patterns internally. For instance, Java Swing heavily relies on the Observer Pattern, while Adapter patterns are utilised in input and output stream readers. For individuals interested in expanding their skill set, it’s worth exploring how these patterns intersect with real-world applications, which can be beneficial for those considering a career in the tech industry or pursuing a Software Testing Course In Bangalore.
Mastering Design Patterns in Java is vital for anyone delving into Object-Oriented Java programming. These patterns offer a systematic approach to solving recurring design issues. Some key advantages of utilising Design Patterns in Java include:
Reusability: Being template solutions, they can be easily reused across various projects.
Proven Solutions: They are tried and tested solutions crafted by experienced software developers over the years.
Enhanced Application Design: They promote transparency and improve the overall design of applications.
Simplified Communication: They facilitate smooth communication among developers, as they provide a common language and approach to solving design problems.
When Should We Use Design Patterns in Java?
Design Patterns aid developers in formulating precise and effective solutions by leveraging the packaged knowledge they provide. They enable developers to establish connections between project requirements and existing solutions to similar problems. Therefore, incorporating design patterns during the analysis and design phase of the software development life cycle is a prudent decision, especially for those seeking comprehensive insights into the subject through specialised Java Training in Bangalore.
Categorisation of Design Patterns in Java
Design patterns can be categorised into various groups based on their purpose and functionality. Here are the main categories:
Core Java Design Patterns
- Creational Design Patterns
- Structural Design Patterns
- Behavioral Design Patterns
- J-EE Design Patterns
These cater specifically to enterprise edition-based frameworks such as Spring. Examples include MVC Design Patterns and Dependency Injection Patterns.
Let’s take a look at the subcategories under each of the Core Java Design Patterns:
Creational Design Patterns
Factory Pattern – Delegates the instantiation of a class to its subclasses.
Abstract Factory Pattern – Defines an abstract class or interface without specifying concrete sub-classes.
Singleton Pattern – Ensures a class has only one instance globally accessible.
Prototype Pattern – Allows the cloning of objects to customise them.
Builder Pattern – Facilitates the step-by-step construction of complex objects using simple ones.
Object Pool Pattern – Manages a pool of objects, allowing for their reuse to minimise the cost of creating new ones.
Structural Design Patterns
Facade Pattern – Hides complex subsystem functionalities under a simple higher-level interface.
Bridge Pattern – Decouples functional abstraction from its implementation, allowing both to vary independently.
Composite Pattern – Enables the creation of hierarchical class structures containing complex and primitive objects.
Decorator Pattern – Dynamically adds or extends functionalities during runtime using composition.
Adapter Pattern – Converts the interface of an existing class to create a new one as per client requirements.
Flyweight Pattern – Utilizes existing objects and creates new ones only if no matching object is found.
Proxy Pattern – Creates another object to perform similar functions, hiding sensitive information from the original object.
Check out our newly introduced Graphic Design Courses In Chennai and start your journey in the world of designing. Visit us, have a chat with our trainers and try it!
Behavioural Patterns
Chain of Responsibility Pattern – Passes a request through a chain of objects until it’s handled.
Strategy Pattern – Encapsulates the functionality of each class to facilitate the addition of new behaviors.
Interpreter Pattern – Parses expressions defined with a set of grammar rules.
Iterator Pattern – Sequentially accesses elements of an aggregate object.
Mediator Pattern – Handles complex communication between classes.
Memento Pattern – Saves the current state of an object to restore it later if necessary.
Command Pattern – Separates the object invoking an operation from the one performing it.
State Pattern – Creates objects for each state of the application.
Observer Pattern – Establishes a one-to-one dependency between objects for easy updates in case of changes.
Template Pattern – Eliminates duplication by creating a separate class for common functionalities.
Use of Design Patterns in Real-Life Cases
Factory Design Pattern
In the context of implementing a network interface, utilising an abstract class called ‘Cellular Network’ with abstract methods representing various types of pay-per-minute plans and creating different subclasses to describe these plans, you are implementing the Factory Design Pattern. This pattern enables the creation of objects without specifying their concrete classes, delegating the instantiation logic to the subclasses. For those aiming to delve deeper into the concepts of object-oriented programming and design patterns, it is advisable to consider exploring how this implementation aligns with the fundamentals of Core Java Training in Chennai.
Observer Design Pattern
In the case of multiple users registering on a cricket scores website to receive notifications when a specific event, like Kohli scoring a century, occurs, you are employing the Observer Pattern. In this pattern, the users act as observers that are notified whenever there is a change, or an event occurs in the subject they are observing. In this scenario, the registered users are observing the event of Kohli scoring a century and are notified as soon as this event takes place.
Both design patterns serve distinct purposes in software design and development, with the Factory Design Pattern focusing on creating objects without specifying the exact class and the Observer Design Pattern facilitating a one-to-many dependency between objects, ensuring that multiple observers are notified of any changes in the subject they are observing. For professionals looking to enhance their skills, understanding these design patterns can be an essential aspect of comprehensive Java Training in Chennai.
Read also: Java Interview Questions and Answers