Скачать или смотреть Efficiently Assigning Values in Kotlin: Avoiding Null Repetition

Discover the idiomatic way to handle nullable values in Kotlin using the Elvis Operator, simplifying your code and enhancing readability.
---
This video is based on the question https://stackoverflow.com/q/66825604/ asked by the user 'user1785730' ( https://stackoverflow.com/u/1785730/ ) and on the answer https://stackoverflow.com/a/66825706/ provided by the user 'CryptoFool' ( https://stackoverflow.com/u/7631480/ ) 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: Idiomatic way to assign value if not null

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.
---
Efficiently Assigning Values in Kotlin: Avoiding Null Repetition

In programming, especially when dealing with optional values, it can often feel repetitive and cumbersome to check for nulls. In Kotlin, the need for an effective solution becomes crucial, especially to keep your code clean and maintainable.

Let’s dive into a common scenario where you might want to assign a value based on whether a nullable function returns null or not, and explore the idiomatic way to handle it in Kotlin.

The Problem

You have a function, getNullableValue(), that can return a value or null. You want to assign a variable foo to either this value or a default value computed through another function, computeDefaultValue().

Your initial approach looks something like this:

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

While this works, it involves repeating the call to getNullableValue(), which can be inefficient and reduces code readability.

Your First Attempt

In an effort to eliminate repetition, you came up with the following code:

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

However, this approach raises two concerns:

It’s unclear whether this method is idiomatic or encouraged in Kotlin.

The IDE warns about the empty body within also, suggesting it may not be the best solution.

The Idiomatic Solution

Fortunately, Kotlin provides a more elegant and straightforward way to handle such cases. Enter the Elvis Operator (?:), which simplifies the process of handling nullable values.

Leveraging the Elvis Operator

By using the Elvis Operator, you can streamline your code into a single, clean line:

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

Benefits of the Elvis Operator

Conciseness: Reduces the code length and enhances readability.

Clarity: It’s immediately apparent that if getNullableValue() returns null, computeDefaultValue() will be used.

Fewer Repetitions: The value is fetched only once, mitigating the performance overhead.

A Practical Example

To illustrate how this works, consider the following function implementations:

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

Result Breakdown

When getNullableValue1() is called, it returns null, and 44 gets assigned to foo.

When getNullableValue2() is called, it returns 22, and the value of foo will be 22.

Conclusion

In Kotlin, the Elvis Operator offers a clear and idiomatic way to assign values based on the presence of nulls. It not only simplifies the syntax but also enhances overall code quality by promoting best practices. By adopting this technique, you'll eliminate redundancy and create more maintainable Kotlin code.

Now, whenever you face a situation of assigning values conditionally on null checks, remember the elegant solution offered by the Elvis Operator!