Priority Queue in Java | Priority Queue Using Heap | Priority Queue Implementation in Java

                
                  In this post, we will see Priority Queue in Java | Priority Queue Using Heap | Priority Queue Implementation in Java


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Program Code: (PQueue.java) 

import java.util.*; public class PQueue {       public static void main(String args[]) {       Queue q = new PriorityQueue();       int head;       System.out.println("Queue: " + q);       q.add(10);  //offer()       System.out.println("Queue: " + q);       q.add(25);       System.out.println("Queue: " + q);       q.add(22);       System.out.println("Queue: " + q);       q.add(18);       try{       System.out.println("Queue: " + q);       head=(int)q.remove();  //poll()       System.out.println("Queue: " + q);       head=(int)q.remove();       System.out.println("Queue: " + q);       head=(int)q.remove();       System.out.println("Queue: " + q);       head=(int)q.remove();        System.out.println("Queue: " + q);       head=(int)q.remove();        }       catch(Exception e) {       System.out.println("Queue is empty");      }      } }

  

Output:

parag@parag-Inspiron-N4010:~/Desktop/prog$ javac PQueue.java  Note: PQueue.java uses unchecked or unsafe operations. Note: Recompile with -Xlint:unchecked for details. parag@parag-Inspiron-N4010:~/Desktop/prog$ java PQueue Queue: [] Queue: [10] Queue: [10, 25] Queue: [10, 25, 22] Queue: [10, 18, 22, 25] Queue: [18, 25, 22] Queue: [22, 25] Queue: [25] Queue: [] Queue is empty

        

Explanation:

1. Add 10

Queue: [10]

2. Add 25

Queue: [10, 25]

3. Add 22

Queue: [10, 25, 22]

4. Add 18

Queue: [10, 18, 22, 25]

5. Remove next (head) element 

Queue: [18, 25, 22]

6. Remove next (head) element

Queue: [22, 25]

7. Remove next (head) element

Queue: [25]

8. Remove next (head) element

Queue: [ ]