Java Queue Interface

Java Queue Interface

The Queue interface basically orders the element in FIFO(First In First Out)manner.

Methods of Queue Interface :

1. public boolean add(object);
2. public boolean offer(object);
3. public remove();
4. public poll();
5. public element();
6. public peek();

---

PriorityQueue class:

The PriorityQueue class provides the facility of using queue. But it does not orders the elements in FIFO manner.

Example of PriorityQueue:

1.    import java.util.*;  

2.    class TestCollection12{  

3.    public static void main(String args[]){  

4.      

5.    PriorityQueue<String> queue=new PriorityQueue<String>();  

6.    queue.add("Amit");  

7.    queue.add("Vijay");  

8.    queue.add("Karan");  

9.    queue.add("Jai");  

10. queue.add("Rahul");  

11.   

12. System.out.println("head:"+queue.element());  

13. System.out.println("head:"+queue.peek());  

14.   

15. System.out.println("iterating the queue elements:");  

16. Iterator itr=queue.iterator();  

17. while(itr.hasNext()){  

18. System.out.println(itr.next());  

19. }  

20.   

21. queue.remove();  

22. queue.poll();  

23.   

24. System.out.println("after removing two elements:");  

25. Iterator<String> itr2=queue.iterator();  

26. while(itr2.hasNext()){  

27. System.out.println(itr2.next());  

28. }  

29.   

30. }  

31. }  

Output:head:Amit

       head:Amit

       iterating the queue elements:

       Amit

       Jai

       Karan

       Vijay

       Rahul

       after removing two elements:

       Karan

       Rahul

       Vijay