Ways to use loops in Kotlin with examples: For, While, Do-while, Repeat, Foreach Loop in Kotlin
Learn how to use loops in Kotlin with examples of popular loop structures like for, while, do-while, repeat, and foreach loop.
For loop:
The for loop iterates over a range of values, arrays, or any other iterable object.
Example:
for (i in 1..5) {
println(i)
}
// output
// 1
// 2
// 3
// 4
// 5
for loop with the until
keyword. The until
keyword is used to create a range that excludes the upper bound.
Example:
for (i in 1 until 5) {
println(i)
}
// output
// 1
// 2
// 3
// 4
This loop will iterate from 1 to 4 (inclusive of 1 and exclusive of 5). You can also specify a step value using the step
keyword:
for (i in 1 until 10 step 2) {
println(i)
}
// output
// 1
// 3
// 5
// 7
// 9
This loop will iterate from 1 to 9 with a step of 2 (i.e., it will print 1, 3, 5, 7, and 9).
While loop:
The while loop iterates while the condition is true.
Example:
var i = 1
while (i <= 5) {
println(i)
i++
}
// output
// 1
// 2
// 3
// 4
// 5
do-while loop:
The do-while loop iterates at least once and then check the condition.
Example:
var i = 1
do {
println(i)
i++
} while (i <= 5)
// output
// 1
// 2
// 3
// 4
// 5
ForEach loop:
The forEach loop iterates over each element of an array or a collection.
Example:
val numbers = arrayOf(1, 2, 3, 4, 5)
numbers.forEach {
println(it)
}
// output
// 1
// 2
// 3
// 4
// 5
Repeat loop:
The repeat loop repeats the block of code a specified number of times.
Example:
repeat(5) {
println("Hello")
}
//output
// Hello
// Hello
// Hello
// Hello
// Hello
These are the five main ways to create a loop in Kotlin.