Скачать или смотреть Refactoring Java 8 Stream Code to Avoid Duplication

Learn how to refactor Java 8 stream methods to eliminate duplication in your code by using adaptable predicates.
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This video is based on the question https://stackoverflow.com/q/64442045/ asked by the user 'Michu93' ( https://stackoverflow.com/u/4952262/ ) and on the answer https://stackoverflow.com/a/64444063/ provided by the user 'Shekhar Khairnar' ( https://stackoverflow.com/u/1443840/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Introduction: The Duplication Dilemma in Java 8 Streams

If you're a Java developer, you might have encountered a common issue in programming: code duplication. This is particularly annoying when you are working with methods that have similar logic but differ slightly in their implementation. In Java 8, using streams can sometimes lead to this problem, as demonstrated in the scenario below.

The challenge revolves around two similar methods that perform almost identical operations on different product collections. This not only clutters your code but also makes maintenance and updates more complicated. So, how can we resolve this duplication while maintaining code clarity and functionality? Let’s dive into the solution!

Understanding the Problem

Let's consider the two methods below:

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The Differences

The only line that alters the functionality is the .filter(byIsDoubled(query.isDoubled())) in the findSpecial method. This duplication of the method body is what we want to avoid.

An Elegant Refactoring Approach

Instead of having two separate methods with repetitive code, we can create a unified solution that incorporates the conditional filtering based on the variable requirements. Here's how we can achieve this:

Step 1: Utilizing Predicates

We will create a new method called findConditional that will take a Query object as input and return a composite predicate:

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Step 2: Refactoring the Original Methods

Now, we can refactor both methods to use this new findConditional:

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Benefits of This Approach

1. Reduction of Code Duplication:

By integrating the conditional logic into one method, we eliminate redundancy, making the code cleaner and easier to maintain.

2. Improved Readability:

Each method is more focused and easier to understand, as the filtering logic is encapsulated within the findConditional method.

3. Scalability:

Should additional filtering conditions be required in the future, they can be easily added to the findConditional method without modifying the individual product search methods.

Conclusion

Refactoring is an essential skill for any Java developer looking to write clean, maintainable, and efficient code. In this guide, we tackled the problem of code duplication in Java 8 streams by abstracting repeated logic into a reusable predicate method. With just a few modifications, we turned two cumbersome methods into sleek, efficient solutions that uphold the DRY (Don't Repeat Yourself) principle.

Now it's your turn — try applying this strategy in your applications to enhance overall code quality and maintainability!