Remove an element from an array in Kotlin

This article explores different ways to remove an element from an array in Kotlin.

Arrays hold a fixed number of items of a single type. Since the length of the array is fixed, we cannot remove elements from it. However, we can create a new array without the element being removed.

1. Using `filter()` function

The idea is to filter the array to remove the required element and accumulate the remaining values into a new array. This is demonstrated below for an Int Array.

fun removeTarget(array: IntArray, target: Int): IntArray {

return array

.filter { it != target }

.toIntArray()

}

fun main() {

var array: IntArray = intArrayOf(2, 5, 7, 3, 4, 8, 9)

val target = 4

array = removeTarget(array, target)

println(array.contentToString())

}

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Output:

[2, 5, 7, 3, 4, 8, 9]

2. Using `System.arraycopy()` function

To remove an element from the array using its index, the recommended approach is using the System.arraycopy() function. The idea is to allocate a new array of one less size than the original array, and copy all the elements from the original array into the new array before and after that index.

fun removeByIndex(array: Array<String?>, index: Int): Array<String?> {

val result = arrayOfNulls<String>(array.lastIndex)

System.arraycopy(array, 0, result, 0, index)

if (array.size != index) {

System.arraycopy(array, index + 1, result, index, array.lastIndex - index)

}

return result

}

fun main() {

var array = arrayOf<String?>("A", "C", "B", "C", "D", "E")

val index = 1

array = removeByIndex(array, index)

println(array.contentToString())

}

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Output:

[A, B, C, D, E]

That’s all about removing an element from an array in Kotlin.

Remove an element from an array in Kotlin

1. Using filter() function

2. Using System.arraycopy() function

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1. Using `filter()` function

2. Using `System.arraycopy()` function