How to use the lastOrNull() method of ArrayDeque in Kotlin
Overview
The lastOrNull() method can be used to get the last element of the ArrayDeque. If the ArrayDeque is empty, then null is returned.
Syntax
fun lastOrNull(): E?
Parameter
This method does not take any argument.
Return value
Returns the last element if the ArrayDeque is not empty. Otherwise, null is returned.
Example
The example below demonstrates how to use the lastOrNull() method.
fun main() {// create a new empty ArrayDeque which can have int elementsvar deque = ArrayDeque<Int>()println("The Arraydeque is $deque")// get the last element of dequevar lastEle = deque.lastOrNull();println("The last element is $lastEle");// add four elements to dequedeque.add(1)deque.add(2)deque.add(3)deque.add(4)println("\nThe Arraydeque is $deque")// get the last element of dequelastEle = deque.lastOrNull();println("The last element is $lastEle");}
Explanation
Line 3: We create a new ArrayDeque with the name deque. The deque contains no element [].
Line 7: We use the lastOrNull method to get the last element of the deque. In this case, the deque is empty, so null is returned.
Lines 11–14: We add four elements to the deque using the add method. Now the deque is [1,2,3,4].
Line 18: We use the lastOrNull method to get the deque’s last element(4). The deque is not empty, so the last element of the deque is returned.