Difference Between Peek, Poll, and Remove Methods of Queue Interface in Java

This represents a collection that is indented to hold data before processing. It is an arrangement of the type First-In-First-Out (FIFO). The first element put in the queue is the first element taken out from it.

The peek() method

The peek() method returns the object at the top of the current queue, without removing it. If the queue is empty this method returns null.

Example

 Live Demo

import java.util.Iterator;
import java.util.LinkedList;
import java.util.Queue;
public class QueueExample {
   public static void main(String args[]) {
      Queue<String> queue = new LinkedList<String>();
      queue.add("Java");
      queue.add("JavaFX");
      queue.add("OpenCV");
      queue.add("Coffee Script");
      queue.add("HBase");
      System.out.println("Element at the top of the queue: "+queue.peek());
      Iterator<String> it = queue.iterator();
      System.out.println("Contents of the queue: ");
      while(it.hasNext()) {
         System.out.println(it.next());
      }
   }
}

Output

Element at the top of the queue: Java
Contents of the queue:
Java
JavaFX
OpenCV
Coffee Script
Hbase

The poll() method

The poll() method of the Queue interface returns the object at the top of the current queue and removes it. If the queue is empty this method returns null.

Example

 Live Demo

import java.util.Iterator;
import java.util.LinkedList;
import java.util.Queue;
public class QueueExample {
   public static void main(String args[]) {
      Queue<String> queue = new LinkedList<String>();
      queue.add("Java");
      queue.add("JavaFX");
      queue.add("OpenCV");
      queue.add("Coffee Script");
      queue.add("HBase");
      System.out.println("Element at the top of the queue: "+queue.poll());
      Iterator<String> it = queue.iterator();
      System.out.println("Contents of the queue: ");
      while(it.hasNext()) {
         System.out.println(it.next());
      }
   }
}

Output

Element at the top of the queue: Java
Contents of the queue:
JavaFX
OpenCV
Coffee Script
HBase