Under the hood, the IntRange implementation contains IntProgression class that provides Iterator interface implementation required for iteration.

that allows to declare a range in a more natural way: val range: IntRange = 0.1000 The rangeTo() function has also its very own operator equivalent. The declaration above defines a range of integers of values from 0 to 1000. Let’s take a look at the following example: val range: IntRange = 0.rangeTo(1000) To define a range for the primitive type we use rangeTo() function.

There are built in implementations of ranges for the integral primitive types, like Int, Long and Char. It stores handles to first and last elements of the range and also provides contains(value: T): Boolean and isEmpty(): Boolean functions that check two conditions: if the given value belongs to the range and if the range is empty. An interface from kotlin.ranges package called ClosedRange is a base declaration that models the idea of range. The idea of a range itself can be seen as an abstract data type that models a closed scope of values or a set of objects that can be iterated through, in a concise way.

Next, we are going to implement a custom progression for the LocalDate class. In this post we are going to explore how to use range expressions in action.įirst, we are going to discover a built-in ranges implementations for the integral types like Char, Int or Long. In order to make the syntax for loop iteration and control flow statements safe and natural to read, Kotlin standard library provides a concept of ranges.

Kotlin for each example