Get a subarray of an array between given positions in Kotlin

This article explores different ways to get a subarray of an array between the specified range in Kotlin.

1. Using `copyOfRange()` function

The standard way to get a subarray of an array in Kotlin is to use the extension function copyOfRange(), which returns a new array, a copy of the specified range of the original array.

fun <T> getSubArray(array: Array<T>, beg: Int, end: Int): Array<T> {

return array.copyOfRange(beg, end + 1)

}

fun main() {

val arr = arrayOf('A', 'B', 'C', 'D', 'E', 'F', 'G', 'H')

val beg = 1

val end = 4

val subarray = getSubArray(arr, beg, end)

println(subarray.contentToString()) // [B, C, D, E]

}

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2. Using `System.arraycopy()` function

The System.arraycopy() function can also be used to get a copy from the specified range in the source array to the destination array.

fun main() {

val arr = arrayOf('A', 'B', 'C', 'D', 'E', 'F', 'G', 'H')

val start = 1

val end = 4

val subarray = arrayOfNulls<Char>(end - start + 1)

System.arraycopy(arr, start, subarray, 0, subarray.size)

println(subarray.contentToString()) // [B, C, D, E]

}

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3. Using `subList()` with `toTypedArray()` function

Another plausible way of getting a subarray from an array in the specific range involves using a List. The idea is to convert the array into a list and then use the subList() function to get elements in the specified range. We can then call the toTypedArray() function to convert elements into a new array.

fun main() {

val arr = arrayOf('A', 'B', 'C', 'D', 'E', 'F', 'G', 'H')

val start = 1

val end = 4

val subarray = arr.toList()

.subList(start, end + 1)

.toTypedArray()

println(subarray.contentToString()) // [B, C, D, E]

}

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4. Using `map()` with `toTypedArray()` function

We can also use the map() function to get a list of elements in the specified range, as shown below:

fun main() {

val arr = arrayOf('A', 'B', 'C', 'D', 'E', 'F', 'G', 'H')

val start = 1

val end = 4

val subarray = (start..end)

.map { i: Int -> arr[i] }

.toTypedArray()

println(subarray.contentToString()) // [B, C, D, E]

}

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5. Custom Routine

We can also write our own custom function to copy elements in the specified range from the source array into the new array.

fun main() {

val arr = arrayOf('A', 'B', 'C', 'D', 'E', 'F', 'G', 'H')

val start = 1

val end = 4

val subarray: Array<Char?> = arrayOfNulls(end - start + 1)

for (i in subarray.indices) {

subarray[i] = arr[start + i]

}

println(subarray.contentToString()) // [B, C, D, E]

}

That’s all about getting a subarray of an array between given positions in Kotlin.

Get a subarray of an array between given positions in Kotlin

1. Using copyOfRange() function

2. Using System.arraycopy() function

3. Using subList() with toTypedArray() function

4. Using map() with toTypedArray() function

5. Custom Routine

Share this:

1. Using `copyOfRange()` function

2. Using `System.arraycopy()` function

3. Using `subList()` with `toTypedArray()` function

4. Using `map()` with `toTypedArray()` function