54 lines
1.4 KiB
Plaintext
54 lines
1.4 KiB
Plaintext
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== Why is this an issue?
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Kotlin uses the data type `Unit` to represent the absence of a value in a function or an expression.
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It corresponds to the type `void` in Java or `unknown` in JavaScript.
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While `Void` is available in Kotlin, it is a Java platform type and not equivalent to Java `void` but `java.lang.Void`.
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Use `Unit` instead of `Void` because it represents the absence of a value in Kotlin.
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=== What is the potential impact?
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==== Wrong logic
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`Void` is not equivalent to Java `void` but `java.lang.Void`.
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==== Unnecessary platform dependency
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`Void` is a platform type available only in the Java Runtime Environment.
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== How to fix it
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Replace `Void` with `Unit`.
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=== Code examples
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==== Noncompliant code example
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[source,kotlin,diff-id=1,diff-type=noncompliant]
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----
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typealias NoValueFunction = () -> Void // Noncompliant, `Void` used
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interface NoValueFunctions {
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fun voidFunction1(): Void // Noncompliant, `Void` used
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fun voidFunction2(): Void // Noncompliant, `Void` used
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}
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----
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==== Compliant solution
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[source,kotlin,diff-id=1,diff-type=compliant]
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----
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typealias NoValueFunction = () -> Unit // Compliant, `Unit` used
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interface NoValueFunctions {
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fun unitFunction1(): Unit // Compliant, `Unit` used
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fun unitFunction2() // Compliant, `Unit` used implicitly
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}
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----
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== Resources
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=== Documentation
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* https://kotlinlang.org/docs/functions.html#single-expression-functions[Kotlin Docs, Unit-returning functions]
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