Kotlin List dropWhile()
Syntax & Examples

Syntax of List.dropWhile()

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

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

This dropWhile() extension function of List returns a list containing all elements except first elements that satisfy the given predicate.

✐ Examples

1 Example

In this example,

We create a list of integers list.
We use the dropWhile function with a predicate to drop elements until we encounter an element greater than or equal to 4.
The resulting list result contains elements 4, 5, 6.
Finally, we print the result list to standard output using print statement.

Kotlin Program

fun main(args: Array<String>) {
    val list = listOf(1, 2, 3, 4, 5, 6)
    val result = list.dropWhile { it < 4 }
    print(result)
}

Output

[4, 5, 6]

2 Example

In this example,

We create a list of characters list.
We use the dropWhile function with a predicate to drop elements until we encounter 'c'.
The resulting list result contains elements c, d.
Finally, we print the result list to standard output using print statement.

Kotlin Program

fun main(args: Array<String>) {
    val list = listOf(&quot;a&quot;, &quot;b&quot;, &quot;c&quot;, &quot;d&quot;)
    val result = list.dropWhile { it != &quot;c&quot; }
    print(result)
}

Output

[c, d]

3 Example

In this example,

We create a list of strings list.
We use the dropWhile function with a predicate to drop elements until we encounter an element with a length greater than or equal to 6.
The resulting list result contains elements mango, avocado.
Finally, we print the result list to standard output using print statement.

Kotlin Program

fun main(args: Array<String>) {
    val list = listOf(&quot;apple&quot;, &quot;banana&quot;, &quot;mango&quot;, &quot;avocado&quot;)
    val result = list.dropWhile { it.length < 6 }
    print(result)
}

Output

[banana, mango, avocado]

Summary

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