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Learn how to refactor your Java method to comply with the rule of a single return statement while maintaining its functionality.
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This video is based on the question https://stackoverflow.com/q/63626411/ asked by the user 'TheAvenger321' ( https://stackoverflow.com/u/10888307/ ) and on the answer https://stackoverflow.com/a/63626440/ provided by the user 'WJS' ( https://stackoverflow.com/u/1552534/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Modify Your Java Method to Have Only One Return Statement

When writing methods in Java (or any programming language), you might encounter certain guidelines or rules that aim to improve code clarity and maintainability. One such rule is that there should only be one return statement in a method. This can raise questions, especially when you're trying to maintain functionality. In this post, we’ll look at a common problem and break down the solution step-by-step.

The Problem

You might have a simple Java method that contains two return statements, like the following:

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In this method, we search for a specific number (correctNumber) within an array (numArray). If the number is found, we return its index; otherwise, we return -1 to indicate it's not present. However, this method has two return statements, and your professor requires methods to only have one.

So how can you restructure this method without losing its functionality?

The Solution

1. Use an Additional Variable

To reduce the number of return statements, we can introduce a variable that holds the return value. We’ll initialize this variable to a default value (in this case, -1) before the loop starts.

2. Implement the Logic Inside the Loop

Instead of returning immediately when the number is found, we’ll assign the value of the index to our variable and then break out of the loop.

Refactored Code

Here’s how the refactored method looks:

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Explanation of Changes

Variable Initialization: The variable returnValue is initialized to -1. This denotes that the number hasn't been found.

Updating Value: If correctNumber is found in the array, we update returnValue to the current index i.

Single Return Statement: After exiting the loop, we return the value stored in returnValue. Now, the method adheres to the rule of a single return statement.

An Important Note

While it's important to follow guidelines set by instructors or projects, professional programmers often find it acceptable to use multiple return statements for better readability and efficiency. For instance, consider the equals method from the JDK HashMap source:

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This method features multiple returns, demonstrating that clarity and functionality can sometimes outweigh the single-return guideline.

Conclusion

Refactoring your Java methods to adhere to a single return statement may initially seem challenging, but using a simple variable can streamline the process while keeping your code functional. Remember, though, standards may vary across programming environments, so it's always good to understand when it's appropriate to flex those rules.

By breaking down problems like this, you can enhance both your coding skills and your understanding of Java's structural conventions.