Kotlin List toHashSet()
Syntax & Examples

Syntax of List.toHashSet()

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

fun <T> Iterable<T>.toHashSet(): HashSet<T>

This toHashSet() extension function of List returns a new HashSet of all elements.

✐ Examples

1 Example

In this example,

We create a list named list containing integers and some duplicate elements.
We call the toHashSet() function on list.
The resulting HashSet, which contains unique elements, is stored in set.
Finally, we print the HashSet to standard output.

Kotlin Program

fun main(args: Array<String>) {
    val list = listOf(1, 2, 3, 4, 5, 5, 4, 3, 2, 1);
    val set = list.toHashSet();
    println(set);
}

Output

[1, 2, 3, 4, 5]

2 Example

In this example,

We create a list named list containing characters and some duplicate elements.
We call the toHashSet() function on list.
The resulting HashSet, which contains unique elements, is stored in set.
Finally, we print the HashSet to standard output.

Kotlin Program

fun main(args: Array<String>) {
    val list = listOf('a', 'b', 'c', 'c', 'b', 'a');
    val set = list.toHashSet();
    println(set);
}

Output

[a, b, c]

3 Example

In this example,

We create a list named list containing strings and some duplicate elements.
We call the toHashSet() function on list.
The resulting HashSet, which contains unique elements, is stored in set.
Finally, we print the HashSet to standard output.

Kotlin Program

fun main(args: Array<String>) {
    val list = listOf("apple", "banana", "apple", "banana");
    val set = list.toHashSet();
    println(set);
}

Output

[banana, apple]

Summary

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