Kotlin Priority Queue Example

In this tutorial, I'll demonstrate Kotlin Priority Queue and explain with examples.

What is Priority Queue?

Priority Queue is a queue extension with the properties listed below.

1. There is a priority assigned to each item.
2. A high-priority element is dequeued first, followed by a low-priority element.
3. When two components have the same priority, they are served in the order in which they appeared in the queue.

Kotlin - PriorityQueue Function

1. add(element: E) or offer(element: E): Both are functions of PriorityQueue used to add item to the queue. PriorityQueue implements two interfaces -collections (uses add) and Queue (uses offer).
2. peek() : Get the head of the item from the queue without deleting it.
3. poll(): Remove/delete the head of the item from the queue.

Priority Queue in Kotlin

package com.techgeeknext

import java.util.PriorityQueue

fun main(args: Array<String>)
{
  //Highest Priority Queue
  val employeesIds = PriorityQueue<Int> {
   a, b -> b - a
 }

 // Add 33, 65, 78 , 2 to the employeesIds
 employeesIds.offer(33)
 employeesIds.offer(65)
 employeesIds.offer(78)
 employeesIds.add(2)

 //peek will not remove the item
 employeesIds.peek() // output: 78 

 while(!employeesIds.isEmpty()) {
    employeesIds.poll() // output: 78, 65, 33, 2
 }

}