How to implement a queue in java

How is a queue implemented?

Queue can be implemented using an Array, Stack or Linked List. The easiest way of implementing a queue is by using an Array. Initially the head(FRONT) and the tail(REAR) of the queue points at the first index of the array (starting the index of array from 0 ).

How do you create a queue in Java?

Java PriorityQueue Example

  1. import java.util.*;
  2. class TestCollection12{
  3. public static void main(String args[]){
  4. PriorityQueue queue=new PriorityQueue();
  5. queue.add(“Amit”);
  6. queue.add(“Vijay”);
  7. queue.add(“Karan”);
  8. queue.add(“Jai”);

How are queues implemented using arrays Java?

To implement a queue using array, create an array arr of size n and take two variables front and rear both of which will be initialized to 0 which means the queue is currently empty. Element rear is the index upto which the elements are stored in the array and front is the index of the first element of the array.

How is Java priority queue implemented?

The PriorityQueue class implements the Queue1 interface in Java. … The elements of the priority queue are ordered according to the natural ordering, or by a comparator provided at construction time of the queue, depending on which constructor is used. Below is the visualization of implementing a PriorityQueue.

What is queue example?

A queue is a container of objects (a linear collection) that are inserted and removed according to the first-in first-out (FIFO) principle. An excellent example of a queue is a line of students in the food court of the UC. … In the queue only two operations are allowed enqueue and dequeue.

What are the five basic operations on a queue?

Basic Operations

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enqueue() − add (store) an item to the queue. dequeue() − remove (access) an item from the queue.

How do I know if my queue is full?


  1. Check whether queue is Full – Check ((rear == SIZE-1 && front == 0) || (rear == front-1)).
  2. If it is full then display Queue is full. If queue is not full then, check if (rear == SIZE – 1 && front != 0) if it is true then set rear=0 and insert element.

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How do I add to my queue?

The operation of adding /inserting elements in the queue is called “enqueue”.

In this process, the following steps are performed:

  1. Check if the queue is full.
  2. If full, produce overflow error and exit.
  3. Else, increment ‘rear’.
  4. Add an element to the location pointed by ‘rear’.
  5. Return success.

Is a linked list a queue?

In Java (and probably other languages too), a LinkedList implements the Queue interface. So in essence, a LinkedList is a Queue; it has all features that a Queue does and more. Keep in mind, a Queue is not a LinkedList, as a LinkedList is built and expanded upon a Queue.

What are the types of queues?

Types of Queues in Data Structure

  • Simple Queue. Image Source. As is clear from the name itself, simple queue lets us perform the operations simply. …
  • Circular Queue. Image Source. …
  • Priority Queue. Image Source. …
  • Doubly Ended Queue (Dequeue) Image Source.

What will the operation enqueue do if the array is full?

Enqueue: Adds an item to the queue. If the queue is full, then it is said to be an Overflow condition. Dequeue: Removes an item from the queue.

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What is the use of priority queue?

The priority queue (also known as the fringe) is used to keep track of unexplored routes, the one for which a lower bound on the total path length is smallest is given highest priority. Heap Sort : Heap sort is typically implemented using Heap which is an implementation of Priority Queue.

What is priority queue with example?

In a priority queue, an element with high priority is served before an element with low priority. In some implementations, if two elements have the same priority, they are served according to the order in which they were enqueued, while in other implementations, ordering of elements with the same priority is undefined.

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