Top Linked List data structure interview questions and answers

Linked List Data structure

A linked list is a linear data structure where each element is a separate object. Here is the top (most commonly) asked question in the Java interview. A linked list is one of the most favorite topics during the data structure and algorithms interview process.

Linked list interview questions java interviews

We are starting  from basic  :

Here is the code of LinkedList, as you know java JDK already providing a Collection of data structure. So LinkedList class already provided in java.util. Here we share a basic level of knowledge of LinkedList. So start with the program how to create a simple LinkedList, then go to a deep level.


public class LinkedList {
    Node head; // head of list
    // Linked list Node.  This inner class is made 
    // static so that main() can access it
    static class Node {
        int data;
        Node next;
        Node(int d) {
            data = d;
            next = null;
    // Method to print all nodes
    public void printList() {
        Node n = head;
        System.out.print(" head");
        while (n != null) {
            System.out.print(" -> " +;
            n =;
    public static void main(String a[]) {
        //create a simple linked list with 5 nodes
        LinkedList linkedList = new LinkedList();
        linkedList.head = new Node(2);
        Node second = new Node(4);
        Node third = new Node(5);
        Node fourth = new Node(2);
        Node fifth = new Node(1); = second; = third; = fourth; = fifth; = null;// not needed to assign null

Now, let’s start the Most common and top Linked List data structure interview questions in Java. It’s also an important question for Android app developers.

Question #1. How to Find Length of a Linked List (Iterative and Recursive)

Answer  : Iterative : The Iteration is applied to the set of instructions which we want to get repeatedly executed.

RecursiveRecursion is a process, where statement in a body of function calls the function itself.

Coding is here Find Length of a LinkedList

Question #2. How to Insert a new node in a linked list data structure

Answer : Inserting new node in linked list can do 3 ways.

  • At the start of the Linked list
  • In the middle of the Linked list
  • At the end of the Linked list

Here is all 3 ways to inserting data in linked list with code : Insert a new node in a linked list

Question #3. In given a Linked List,  find the middle of the list and print the number.

Input : -> 4-> 2-> 7-> 9-> 1

Output : 7

#Single pointer approach

In this approach, we will scan the entire list and count the number of nodes. We divide the number by 2 and then again traverse the list up-to that node.

#Using 2 pointers

With 2 pointers to traverse the list ,we can find the middle of list with only one scan on the Linked List.

  • pointer1 travels one node at a time
  • pointe2 travels two nodes a time.

Thus, when pointer2 reaches the end of the Linked List, pointer1 will point at the middle of the Linked List.

For more details and code : Find the middle of a given linked list

Question #4. Given a Linked List and a number n, write a program that finds the value at the nth node from the end of the Linked List.

Answer : You can find n’th node using length of linked list

Complete tutorial :Program for n’th node from the end of a Linked List

Question #5. Given the pointer to the head node of a linked list, the task is to reverse the linked list. You need to reverse the list by changing links between nodes.

Solutions : Iterative Method

1. Initialise three pointers

currentNode = head;  nextNode = null;  previousNode = null;

2. Iterate trough the linked list. In while loop, do following.
//store next node
currentNode = currentNode->nextNode

// Revers node pointers

currentNode -> next = previousNode 

// Move previous and current node one step forward
previousNode =currentNode
currentNode = nextNode

complete code example check this post : Reverse a Linked list data structure in java

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