Design Patterns in Java

Java Design Patterns are the best formalized practices a developer can solve common problems when designing an application or system. With the help of tried and tested software development paradigms, design patterns can be utilized to speed up the development process. Reusing these design patterns helps in preventing issues that can cause major problems. It also improves code readability for java coders and architects who are familiar with the design patterns in java.  But here the question arises what is design pattern in java?

A design pattern is a reusable solution for typical problems that arise during software development. The relationships and interactions between classes or objects are generally depicted using patterns in Java. The goal is to make the development process go faster by providing tried-and-true development/design paradigms.

Design patterns are problem-solving methodologies that are independent of programming languages. It’s a representation of a concept rather than a specific execution. You can make your code more flexible, reusable, and maintained by utilizing java programming patterns.

Now that you have a clear idea what java design patterns is. Let’s look at the benefits of design patterns in java.

Benefits Of Using Java Design Patterns

Using Java design patterns in software development offers numerous advantages. Design patterns provide proven solutions to common problems, ensuring code reusability and maintainability. They promote modular and loosely coupled designs, making code easier to understand, modify, and extend. Following are some of the benefits of using Java Design Patterns.

• Reusable in multiple projects
• Provide the solutions to help define the system architecture
• Helps in establishing best practices
• Documents the software experience
• Improved code organization
• Provides transparency to the design
• Well proved and testified solutions
• Provides clarity to the system architecture

When to use Design patterns in java?

Generally, design patterns should be used when you encounter recurring problems or challenges in software development. Below are some of the situations where using design patterns is beneficial.

• Common Problems: When you face some common design challenges or software development challenges its useful to apply design patterns. These patterns provide established solutions that have proven to work efficiently in similar situations.
• Code Reusability: To promote code reusability and avoid reinventing solutions for same problem again and again, design patterns can be useful. With the reusable templates & structure that can be applied across different projects and contexts these design pattern in java offers code reusability.
• Performance Optimization: In cases where performance optimization is a concern, certain design patterns offer efficient solutions. Patterns like Flyweight or the Singleton patterns can help reduce memory consumption, improve resource utilization, and enhance overall system performance.
• Collaboration & Communication: Design patterns serve as a common language among the developers. Using design patterns while working in a team or collaborating on the project, helps in improvising communication and understanding among team members.
• Scalability and Flexibility: If you anticipate the need for scalability and future enhancements in your software, design patterns can assist in designing flexible and extensible systems. Patterns provide guidelines for building software architectures that can accommodate changes and growth without requiring significant rework.

Now that we know what is a design pattern in java along with its benefits. Let’s understand the Gang of four (GoF) design patterns.

What are GoF Design Patterns?

A design pattern concept in software development was first introduced with this java design patterns book “Design Patterns – Elements of Reusable Object-Oriented Software”, written by four writers Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides, was published in 1994.

Collectively these authors are known as “Gang of Four”. Design patterns, according to these authors, are essentially based on the following object-oriented design paradigm.

• Not an implementation, but a program to an interface
• Object composition is preferred over an inheritance

Also Read: – Top Java Development Tools to utilize

GoF Design Patterns Categories

According to design pattern reference book “Design Patterns – Elements of Reusable Object-Oriented Software”, there are 23 design patterns in java, are classified in 3 categories: Creational, Structural and Behavioural Pattern. Apart from these design pattern there is one other category of Java design patterns which is JEE design patterns. But for this blog we will discuss core design patterns in java.

Creational Patterns

As the name suggests creational patterns in java, it focuses on the creation of objects in a software system. It deals with the how objects are instantiated and created, providing mechanism to create objects in a flexible and decoupled manner.

Types of Creational Patterns

In Java, there are several common types of creational design patterns that facilitate object creation. These patterns include Singleton for creating a single instance, Factory Method for flexible object creation, Abstract Factory for creating families of related objects, Builder for constructing complex objects, and Prototype for object cloning and duplication. Let’s take a comprehensive look at each one of them.

Factory Method

Factory design pattern in java defines an abstract class or interface for creating an object but leaves it up to subclasses to create the instance of class.

Abstract Factory

Abstract factory design pattern in java creates interface is responsible for creating a factory of related objects without explicitly defining their classes.

Builder

Builder design pattern java allows using the same building code, to create numerous types & representations for an object.

Singleton

Singleton design pattern java has main intent of ensuring that only one object of class is created and provides a global point of access to it, like having one unique boss in a game.

Object Pool

This java design patterns manages and reuses a collection of pre-created objects, for example like a pool of rental bikes that one can borrow and return.

Prototype

This design pattern in java as the name suggests allows developing new objects by copying the existing objects, for example using a same template to make an identical object.

Creational Patterns Use cases

Java’s creational design patterns enable quick object creation, ensuring single insrances and flexible development of complex objects. The following are some situations in which you can use Java’s creational design patterns.

• Object Instantiation
• Singleton Instance
• Object Composition
• Creating related objects
• Object pooling
• Object Initialization

Structural Patterns

Java’s structural patterns focus on the way that classes and objects are put together to create huge structures. By highlighting the relationships, the structural design patterns make the structure easier to understand. These patterns concentrate on how classes are built from other classes and how they inherit from one another.

Types of Structural Patterns

In Java, structural design patterns provide solutions for organizing classes and objects to form larger structures. Common types include Adapter for interface compatibility, Decorator for adding behaviour to objects, Proxy for controlling access to objects, and Composite for treating objects as a tree-like structure. Let’s examine each one of them.

Adapter

adapter design pattern in java works as a middle man between two different things so that they can work together.

Bridge

Bridge design pattern in java, allows you to split the large set of classes or class in two separate hierarchy’s implementation and abstraction, which can be developed independently.

Composite

Composite design pattern java allows you to compose the objects into tree structure and work with these structures as individual objects.

Decorator

Decorator design pattern in java allows you to add an extra feature to an object dynamically. The object is placed inside the special wrapper that contains behaviours, for better understanding imagine a Matryoshka dolls set.

Façade

Facade design pattern in java provides a simple interface for complex subsystems or set of classes.

Flyweight

This java design pattern allows you to share the common parts of object allowing you save memory and enhance performance.

Proxy

Proxy design pattern in java acts as a placeholder or representative for another object, controlling access to it & adds an extra functionality if required. It works as an assistant who screens the calls and emails for boss.

Also Read: – Top Java Framworks to use

Structural Patterns Use Case

Java’s structural design patterns offer ways to arrange classes, control relationships, and streamline the architecture of large systems. Listed below are some instances in which Java’s structural design pattern can be used.

• Clean Separation
• Dependency Handling
• Simplification
• Code Reusability
• Relationship Management
• Hierarchical Structures

Behavioural Patterns

Behavioural patterns in java as the name suggests is used to identify the behaviour of the communication. It focuses on recognising the communication patterns between the objects and realizing these patterns.

Types of Behavioural Patterns

In Java, behavioural design patterns provide solutions for communication and interaction between objects. Common types include Observer for event handling, Strategy for interchangeable algorithms, Command for encapsulating requests, and Template Method for defining algorithm structure. Let’s look at them closely.

Chain of Responsibility

Chain of responsibility design pattern java allows you to pass the requests along chain of handlers. Once the request is received each handler can either process the request or pass it on to the next handler in chain. it is like the customer support system where each request is handled by different level of support staff.

Command

Command design pattern in java encapsulates a request as an object, allowing it to be parameterized, queued, logged, and reversed.

Iterator

This design pattern in java allows you to sequentially access elements without exposing its underlying representation.

Mediator

This java design patterns allows you to reduce dependencies between objects. It acts like a mediator where participants can send messages to each other.

Memento

Captures and restores the internal state of an object without revealing its details of implementation. Think of it as loading the game at different level.

Observer

Notifies and updates objects automatically when the state of another object changes, like receiving notifications on a phone when a new message arrives.

State

State design pattern in java gives an object the ability to alter its behaviour in response to changes in its internal state, much as an object changing classes.

Strategy

Strategy design pattern in java lets you create an entire set of algorithms, encapsulates them, and make them all compatible. The algorithm can change without being affected by the clients who utilize it thanks to strategy.

Template Method

The skeleton of an algorithm is provided, enabling subclasses to define stages while maintaining the overall structure of the algorithm, such as performing a task in a specific order.

Visitor

The ability to introduce new operations without changing the objects is made possible by separating an algorithm from the objects that it acts on.

Behavioural Patterns Use Case

To improve flexibility and maintainability, Java’s behavioral design patterns take into account object interaction, behavior encapsulation, and workflow management. These are a couple of instances in which the Java behavioural design pattern can be implemented.

• State Management:
• Managing Complex Workflows
• Encapsulating Responsibilities
• Event Handling
• Compressing Algorithms
• Managing Object Interactions

Java Design Pattern Best Practices

To ensure successful implementation and optimize their benefits, it’s critical to adhere to a few best practices when dealing with Java design patterns. The following are some recommended methods for utilizing Java design patterns:

• Follow the KISS Rule: i.e., Keep it Short & Simple
• Focus on loosely coupled code
• Design First, and then code
• Follow “wu Ji bi fan” as Jackie Chan said in karate kid which means “too much of anything isn’t good”.

Wrapping Up!

Java design patterns offer proven solutions for software challenges, improving code organization, maintainability, and scalability. They promote reusability, collaboration, and industry best practices. Applying patterns judiciously enhances software design while avoiding complexity. Utilizing Java design patterns leads to well-designed, maintainable, and efficient software systems. But keep in mind that as any other thing, excess use of design patterns will make your program more complex and harder to read. So, it is important that you use the java design patterns appropriately when required.