Difference Between Priority Queue and Queue Implementation in Java

The queue is a linear data structure that inserts elements from the back and removes elements from the starting end of the queue.

A priority queue is an extended version of the normal queue with priorities for each element. In this tutorial, we learn about the queue and priority queue in Java with individual implementation.

Difference between Priority Queue and Queue in Java

Implementation of Priority Queue and Queue in Java

Example 1

Queue Implementation in Java

Syntax for queue

Queue<data type> queue_name = new LinkedList<>();

Code to Implement Queue in java

import java.util.*; // importing util package with all its features
public class Main  {
   public static void main(String[] args) {
      Queue<Integer> q = new LinkedList<>(); // queue declaration
	  q.add(5); //adding elements to the queue
	  q.add(6);
      q.add(4);
      q.add(1);
      q.add(8);
		
	  System.out.println("Queue is" + q);
      System.out.println("Removing queue element: " + q.remove());
      System.out.println("Now the Queue is: " + q);
   }
}

Output

Queue is [5, 6, 4, 1, 8]
Removing queue element: 5
Now the Queue is: [6, 4, 1, 8]

Example 2

Priority Queue Implementation in Java

Syntax of Priority Queue

PriorityQueue <data type> queue_name = new PriorityQueue<>();

Code to Implement Priority Queue in Java

import java.util.*;

public class PriorityQueueExample {
   public static void main(String[] args) {
      //declaring priority queue q of string type
     
      PriorityQueue <String> p = new PriorityQueue<>(); 
	  // inserting elements into the priority queue
     
      p.add("Life");
	  p.add("is");
	  p.add("Coding");
      System.out.println("Priority Queue is " + p);
   }
}

Output

Priority Queue is [Coding, is, Life]

Example 3

poll() method in Priority Queue

import java.util.*;

public class PriorityQueueExample {
   public static void main(String[] args) {
      PriorityQueue <Integer> p = new PriorityQueue<>();
      p.add(5);
      p.add(7);
      p.add(1);
      System.out.println("Priority Queue is: " + p);
      int i = p.poll();
      System.out.println("Head element: " +i);
      System.out.println("Queue after removing head element: "+p);
   }
}

Output

Priority Queue is: [1, 7, 5]
Head Element: [1]
Queue after removing head element: [5, 7]

Conclusion

Queue in Java is a linear data structure and is used in the Breadth First Search algorithm. Priority Queue is an extension of normal queue and it is an interface in java with associated priority with each of its elements. One can use various Queue functions to use its features.