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Java program to retrieve an element from the head of the queue without removing it

Java example to retrieve an element from the head of the queue without removing it.
Submitted by Nidhi, on April 27, 2022

Problem Solution:

In this program, we will create a queue using the Queue interface with the help of Linked List collection and store elements in a FIFO (First In First Out) manner. Then we will use the element() and peek() method. Both methods are used to retrieve an element from the head of the queue without removing it.

Program/Source Code:

The source code to retrieve an element from the head of the queue without removing it is given below. The given program is compiled and executed successfully.

// Java program to retrieve an element from the head of 
// the queue without removing it

import java.util.LinkedList;
import java.util.Queue;

public class Main {
  public static void main(String[] args) {
    Queue < Integer > queue = new LinkedList < > ();

    queue.add(10);
    queue.add(20);
    queue.add(30);
    queue.add(40);
    queue.add(50);

    System.out.println("Queue elements: ");
    for (int item: queue) {
      System.out.print(item + " ");
    }

    System.out.println("\n\nElement from head: " + queue.element());
    System.out.println("Element from head: " + queue.peek());

    System.out.println("\nQueue elements: ");
    for (int item: queue) {
      System.out.print(item + " ");
    }
  }
}

Output:

Queue elements: 
10 20 30 40 50 

Element from head: 10
Element from head: 10

Queue elements: 
10 20 30 40 50 

Explanation:

In the above program, we imported the "java.util.LinkedList" and "java.util.Queue" packages to use the Queue Interface and LinkedList collection respectively. Here, we created a class Main. The Main class contains a main() method. The main() method is the entry point for the program.

In the main() method, we created a queue using the LinkedList collection and added items to it. Then we used element(), peek() methods to access the head element from the queue and printed the result.

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