Tuesday, 11 August 2020

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: [ ]




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