Articles

Receivers and Extensions

Use Kotlin extensions to add new functions and properties to existing classes - even to classes that you didn't write! Learn all about explicit receivers, implicit receivers, extension functions, and extension properties in this chapter.

Collections: Maps

Maps in Kotlin are used to associate keys and values. In this chapter, we'll learn all about them, including mutable and immutable maps, map operations like forEach() and filter(), and how to convert lists into maps with associate() and groupBy().

Collections: Lists and Sets

Kotlin collections give you powerful control over groups of objects. In this chapter, we'll look at List and Set collection types, and we'll learn about collection operations - including mapping, filtering, and sorting.

Lambdas and Function References

In Kotlin, you can pass a chunk of code from one function to another. In this chapter, we'll learn how to do that, covering topics like function types, function references, lambdas, higher-order functions, and much more.

Nulls and Null Safety

In Kotlin, null safety is a first-class concept. In this chapter, we'll learn all about nulls, including how to manage them with tools like smart casts, elvis operators, safe-call operators, and more.