How to use the lastIndexOf() method of ArrayDeque in Kotlin
Overview
The lastIndexOf() method will return the index of the last occurrence of the specified element in the ArrayDeque object.
Syntax
fun lastIndexOf(element: E): Int
Parameter
This method takes the parameter element, which represents the element to be searched in the deque.
Return value
This method returns the last index at which the specified element is present in the deque.
If the element is not present in the deque, then -1 is returned.
Code
The method below demonstrates how to use the lastIndexOf() method.
fun main() {
// create a new deque which can have string elements
var deque = ArrayDeque<String>()
// add three elements to dequeu
deque.add("one");
deque.add("one");
deque.add("two");
deque.add("three");
println("\nThe deque is " + deque);
// get lastIndexOf "one"
println("\ndeque.lastIndexOf('one') : " + deque.lastIndexOf("one"));
// get lastIndexOf "five"
println("\ndeque.lastIndexOf('five') : " + deque.lastIndexOf("five"));
}Explanation
In the code above,
-
Line 3: We create an
ArrayDequewith the namedeque. -
Lines 6–9: We use the
addmethod to add four elements to thedeque. Now thedequeis {one,one,two,three}. -
Line 14: We use the
lastIndexOfmethod of thedequeobject to get the index of the last occurrence of the element “one”. The element “one” is present at two indices: 0 and 1. We get1as a result since that is the last occurrence. -
Line 17: We use the
lastIndexOfmethod of thedequeobject to get the index of the last occurrence of the element “five”. The element “five” is not present so-1is returned.
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