when is Kotlin's answer to if/else if/else structures.

The simplest use of when is a bit like a Java switch statement. The when itself gets an expression in parentheses. The contents of the when code block consists of values separated from Kotlin statements or blocks by -> symbols. Then, the value from the when expression is compared against each of those values. If there is a match, the corresponding statement or block is executed. Using the keyword else as the value provides a statement or block to execute if none of the other values matched.

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Capturing Values in when enum and when() when when as an Expression when with Commas when with Expressions for Branches when with Ranges when Without an Expression when Works with Any Type
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