Queue Interface in Java

Queue Interface in Java

Queue Interface defines the queue data structure, which stores elements in the order in which they are inserted. New additions go to the end of the line, and elements are removed from the front. It creates a first-in first-out system.

Methods of Queue Interface

• public boolean add(object)
• public boolean offer(object)
• public remove()
• public poll()
• public element()
• public peek()

Queue Interface can be implement using following classes;

• PriorityQueue
• ArrayDeque

PriorityQueue

import java.util.*;
class PriorityQueueDemo
{
public static void main(String args[])
{  
   
  PriorityQueue<String> queue=new PriorityQueue<String>();  

  // Add Elements
  queue.add("Deo");
  queue.add("Smith");  
  queue.add("Piter");  
  queue.add("Poter");  
  
System.out.println("Iterating the queue Elements:");  
Iterator itr=queue.iterator();  
while(itr.hasNext()){  
System.out.println(itr.next());  
 }  
}  
}  

Iterating the queue Elements:
Deo
Smith
Piter
Porte

PriorityQueue

import java.util.*;
class PriorityQueueDemo
{
public static void main(String args[])
{  
   
  PriorityQueue<String> queue=new PriorityQueue<String>();  

  // Add Elements
  queue.add("Deo");
  queue.add("Smith");  
  queue.add("Piter");  
  queue.add("Poter");  
  
  // Removing Elements
  queue.remove();  
  queue.poll();  

System.out.println("Removing the queue Elements:");  
Iterator itr=queue.iterator();  
while(itr.hasNext()){  
System.out.println(itr.next());  
 }  
}  
}  

Removing the queue Elements:
Piter
Porte