Both provide the same capabilities, so we describe the pros and cons of each for different use cases and provide recommendations for their use.Kotlin has a concept called qualified returns, which means return statements inside lambdas ( like the one passed to forEach) need to be handled differently. Each scope function uses one of two ways to reference the context object: as a lambda receiver ( this) or as a lambda argument ( it). Inside the lambda passed to a scope function, the context object is available by a short reference instead of its actual name. The way they refer to the context object. There are two main differences between each scope function: Distinctionsīecause scope functions are similar in nature, it's important to understand the differences between them. action - function that takes the index of an element and the element itself and performs the action on the element.

We also recommend that you avoid nesting scope functions and be careful when chaining them because it's easy to get confused about the current context object and value of this or it. Performs the given action on each element, providing sequential index with the element. The use cases of different scope functions overlap, so you can choose which functions to use based on the specific conventions used in your project or team.Īlthough scope functions can make your code more concise, avoid overusing them: it can make your code hard to read and lead to errors. Grouping function calls on an object: with Running statements where an expression is required: non-extension run Object configuration and computing the result: run Introducing an expression as a variable in local scope: let Here is a short guide for choosing scope functions depending on the intended purpose:Įxecuting a lambda on non-null objects: let Create a list where each element represents the number of guests that RSVPd from each family.

action - function that takes the index of an element and. Delete the existing code in the Kotlin Playground and have an empty main() function. Performs the given action on each element, providing sequential index with the element. No: takes the context object as an argument.ĭetailed information about these functions is provided in the dedicated sections below. This index variable will keep incrementing by 1 each time until you reach the last index of the list, after which you exit the loop.

Kotlin for each with index