Скачать или смотреть Efficiently Compare String with toString() Representation of Enum Values in Java

Discover how to use `switch` statements with enum values in Java and optimize your code with a mapping approach. Learn best practices today!
---
This video is based on the question https://stackoverflow.com/q/76843490/ asked by the user 'J_code' ( https://stackoverflow.com/u/9784846/ ) and on the answer https://stackoverflow.com/a/76843513/ provided by the user 'rzwitserloot' ( https://stackoverflow.com/u/768644/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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: Compare string with toString() representation of enum value using switch in Java

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Comparing Strings with toString() Representation of Enum Values in Java

If you're working with Java enums, you might find yourself needing to compare strings with the enum's toString() representation. Understanding how to implement this efficiently can make a significant difference in your code's functionality and maintainability, especially when dealing with a vast number of enumerations. In this guide, we'll address a common question developers face: How can you compare strings against enum values using switch statements?

The Problem

You might have a set of enums and a long list of if-statements to manage these comparisons. For instance, you might find yourself writing something like this:

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

While this works fine with a small set of enums, it quickly becomes cumbersome when you need to handle numerous cases. You might want to use a switch statement for cleaner, more efficient code. However, if you try switching on the string representation of your enums, you will probably run into an error like this:

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

The compiler will throw an error indicating that 'toString' has private access in 'MYENUM'.

The Solution

The issue here is that you cannot use the result of a method call (even if it appears constant) in a switch statement because the JVM cannot guarantee that it will always return the same value. Instead, we need an alternative way to achieve the desired outcome, and a mapping approach offers a robust solution.

Creating a Mapping for Enum Strings

Define the Enum: Start by retaining the enum structure, but add a static map that associates each string value with its corresponding enum.

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

Using the Mapping: Instead of a switch statement, you can utilize the of method to retrieve the corresponding enum based on the string.

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

Benefits of This Approach

Performance: Using the map provides O(1) lookup time, which is significantly faster than O(n) when you're checking against many enums. This optimization is particularly useful when dealing with a large number of enumerations.

Clarity and Maintainability: The added mapping makes the code cleaner and easier to manage. You can add new enum values without restructuring your conditional logic.

Flexibility: You can further expand this approach to include methods that can handle more complex logic as needed.

Conclusion

When comparing strings to enum values in Java, moving to a map-driven approach simplifies the complexity of your conditionals. This method not only adheres to best practices for code readability and maintainability but also offers considerable performance improvements for larger sets of enums. By adopting this mapping strategy, you can streamline your Java code and enhance its efficiency in handling enum comparisons.

Now, the next time you face a long list of enum comparisons, remember that switch is not always the answer—sometimes a good mapping is all you need.