Unifying getEntityId and getEntityDTOId with Java Generics

Discover how to efficiently use Java Generics to streamline your code by unifying methods in entities and DTOs. Find practical solutions and tips here!
---

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Generics Entity and EntityDTO similar methods

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Introduction

In the world of Java programming, especially when dealing with Object-Oriented Programming (OOP), one challenge developers often face is the redundancy of similar methods across different classes. A common scenario is having methods like getEntityId and getEntityDTOId in both an Entity class and an EntityDTO class. This can lead to increased maintenance efforts and code clutter.

This guide will introduce an elegant way to unify these methods using Java Generics and interfaces, thus promoting better code reuse and cleaner architecture in your Java applications.

The Problem: Redundant Methods

Consider this snippet of code for two classes: Entity and EntityDTO:

[[See Video to Reveal this Text or Code Snippet]]

Here, the EntityProcessing class has two separate methods to retrieve IDs from the Entity and EntityDTO instances. This redundancy not only makes the code longer but also complicates maintenance and readability.

Solution: Using Java Generics and Interfaces

To solve this problem, we can utilize an interface to unify the methods for getting IDs. Here's how:

Step 1: Define an Interface

First, we will create an interface named WithId that includes the getId method:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Implement the Interface

Next, we need to implement this interface in both the Entity and EntityDTO classes:

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Create a Unified Method

Now that both classes implement the WithId interface, we can define a single method in the EntityProcessing class to handle both types:

[[See Video to Reveal this Text or Code Snippet]]

Benefits of This Approach

Code Reusability: The getId method can now accept any class that implements the WithId interface, minimizing code duplication.

Flexibility: Since implementing an interface allows multiple classes to share the same method name and behavior, you can easily add additional entities or DTOs in the future.

Clarity: This structure clearly indicates that any class which has an ID can be processed similarly.

An Alternative Approach: Abstract Classes

While using an interface is a solid solution, another approach would be to use an abstract class that contains the ID field. However, this option has drawbacks, such as violating the Liskov Substitution Principle, which could complicate future code extensions.

Here’s how you could implement an abstract class:

[[See Video to Reveal this Text or Code Snippet]]

Limitations of the Abstract Class Approach

Single Inheritance: Java allows you to extend only one class, which means you're limited in how many common behaviors you can inherit.

Potential Complexity: If you wish to add additional common methods in the future, like createdDate, you might face difficulties if you're already tied to a single abstract class.

Conclusion

In conclusion, using interfaces to unify similar methods like getEntityId and getEntityDTOId not only simplifies your code but also adheres to Java's design principles. By adopting this approach, you enhance the flexibility and maintainability of your applications.

Feel free to leverage this method in your own projects to reduce redundancy and improve code clarity!