FIFO (First-In-First-Out) approach in Programming

FIFO is an abbreviation for first in, first out. It is a method for handling data structures where the first element is processed first and the newest element is processed last.

Real life example:

In this example, following things are to be considered:

  • There is a ticket counter where people come, take tickets and go.
  • People enter a line (queue) to get to the Ticket Counter in an organized manner.
  • The person to enter the queue first, will get the ticket first and leave the queue.
  • The person entering the queue next will get the ticket after the person in front of him
  • In this way, the person entering the queue last will the tickets last
  • .

  • Therefore, the First person to enter the queue gets the ticket first and the Last person to enter the queue gets the ticket last.

This is known as First-In-First-Out approach or FIFO.

Where is FIFO used:

  1. Data Structures

    Certain data structures like Queue and other variants of Queue uses FIFO approach for processing data.

  2. Disk scheduling

    Disk controllers can use the FIFO as a disk scheduling algorithm to determine the order in which to service disk I/O requests.

  3. Communications and networking

    Communication network bridges, switches and routers used in computer networks use FIFOs to hold data packets en route to their next destination.

Program Examples for FIFO

Program 1: Queue





// Java program to demonstrate
// working of FIFO
// using Queue interface in Java
import java.util.LinkedList;
import java.util.Queue;
public class QueueExample {
    public static void main(String[] args)
        Queue<Integer> q = new LinkedList<>();
        // Adds elements {0, 1, 2, 3, 4} to queue
        for (int i = 0; i < 5; i++)
        // Display contents of the queue.
        System.out.println("Elements of queue-" + q);
        // To remove the head of queue.
        // In this the oldest element '0' will be removed
        int removedele = q.remove();
        System.out.println("removed element-" + removedele);
        // To view the head of queue
        int head = q.peek();
        System.out.println("head of queue-" + head);
        // Rest all methods of collection interface,
        // Like size and contains can be used with this
        // implementation.
        int size = q.size();
        System.out.println("Size of queue-" + size);



Elements of queue-[0, 1, 2, 3, 4]
removed element-0
[1, 2, 3, 4]
head of queue-1
Size of queue-4

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