Kotlin List lastIndex
Syntax & Examples

Syntax of List.lastIndex

The syntax of List.lastIndex extension property is:

val <T> List<T>.lastIndex: Int

This lastIndex extension property of List returns the index of the last item in the list or -1 if the list is empty.


✐ Examples

1 Example

In this example,

  • We create a list named list1 containing the characters 'a', 'p', 'p', 'l', 'e'.
  • We use the lastIndex property on list1 to get the index of the last item in the list.
  • The index of the last item in list1 is stored in the variable index.
  • Finally, we print the value of index to standard output using the println function.

Kotlin Program

fun main(args: Array<String>) {
    val list1 = listOf(&quot;a&quot;, &quot;p&quot;, &quot;p&quot;, &quot;l&quot;, &quot;e&quot;);
    val index = list1.lastIndex;
    println(index);
}

Output

4

2 Example

In this example,

  • We create an empty list named list2.
  • We use the lastIndex property on list2 to get the index of the last item in the list.
  • Since list2 is empty, the lastIndex property returns -1.
  • The result is stored in the variable index.
  • Finally, we print the value of index to standard output using the println function.

Kotlin Program

fun main(args: Array<String>) {
    val list2 = emptyList<String>();
    val index = list2.lastIndex;
    println(index);
}

Output

-1

Summary

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