Kotlin List all()
Syntax & Examples

Syntax of List.all()

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

fun <T> Iterable<T>.all(predicate: (T) -> Boolean): Boolean

This all() extension function of List returns true if all elements match the given predicate.

✐ Examples

1 Example

In this example,

We create a list named list1 containing integers.
We use the all extension function on list1 with a predicate that checks if each element is greater than 0.
The all function returns true if all elements satisfy the predicate; otherwise, it returns false.
Finally, we print the value of result to standard output.

Kotlin Program

fun main(args: Array<String>) {
    val list1 = listOf(1, 2, 3, 4, 5)
    val result = list1.all { it > 0 }
    print(result)
}

Output

true

2 Example

In this example,

We create a list named list2 containing strings.
We use the all extension function on list2 with a predicate that checks if the length of each string is greater than or equal to 5.
The all function returns true if all elements satisfy the predicate; otherwise, it returns false.
Finally, we print the value of result to standard output.

Kotlin Program

fun main(args: Array<String>) {
    val list2 = listOf("apple", "banana", "cherry")
    val result = list2.all { it.length >= 5 }
    print(result)
}

Output

true

Summary

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