Kotlin List toCollection()
Syntax & Examples

Syntax of List.toCollection()

The syntax of List.toCollection() extension function is:

fun <T, C : MutableCollection<in T>> Iterable<T>.toCollection( destination: C ): C

This toCollection() extension function of List appends all elements to the given destination collection.

✐ Examples

1 Example

In this example,

We create a list of integers named list1 with elements 1, 2, 3, 4, 5.
We create an empty mutable list named list2.
We use the toCollection() function on list1 to append its elements to list2.
We then print the elements of list2 using joinToString() to display them separated by commas.

Kotlin Program

fun main(args: Array<String>) {
    val list1 = listOf(1, 2, 3, 4, 5)
    val list2 = mutableListOf<Int>()
    list1.toCollection(list2)
    println(list2.joinToString())
}

Output

1, 2, 3, 4, 5

2 Example

In this example,

We create a list of characters named list1 with elements 'a', 'b', 'c'.
We create an empty mutable list named list2.
We use the toCollection() function on list1 to append its elements to list2.
We then print the elements of list2 using joinToString() to display them separated by commas.

Kotlin Program

fun main(args: Array<String>) {
    val list1 = listOf('a', 'b', 'c')
    val list2 = mutableListOf<Char>()
    list1.toCollection(list2)
    println(list2.joinToString())
}

Output

a, b, c

3 Example

In this example,

We create a list of strings named list1 with elements "apple", "banana", "cherry".
We create an empty mutable list named list2.
We use the toCollection() function on list1 to append its elements to list2.
We then print the elements of list2 using joinToString() to display them separated by commas.

Kotlin Program

fun main(args: Array<String>) {
    val list1 = listOf("apple", "banana", "cherry")
    val list2 = mutableListOf<String>()
    list1.toCollection(list2)
    println(list2.joinToString())
}

Output

apple, banana, cherry

Summary

In this Kotlin tutorial, we learned about toCollection() extension function of List: the syntax and few working examples with output and detailed explanation for each example.