If you want to practice data structure and algorithm programs, you can go through data structure and algorithm interview questions.
In this post, we will see how to reverse a linked list in java.
This is one of popular interview question.
Java Linked List Interview Programs:
 How to reverse a linked list in pairs
 How to find middle element of linked list in java
 How to detect a loop in linked list in java
 Find start node of loop in linkedlist
 How to find nth element from end of linked list
 How to check if linked list is palindrome in java
 Add two numbers represented by linked list in java
There can be two solution to reverse a linked list in java
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 Iterative
 Recursive
Iterative
Logic for this would be:
Have three nodes i.e previousNode ,currentNode and nextNode 

When currentNode is starting node, then previousNode will be null 

Assign currentNode.next to previousNode to reverse the link. 

In each iteration move currentNode and previousNode by 1 node. 
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 
public static Node reverseLinkedList(Node currentNode) { // For first node, previousNode will be null Node previousNode=null; Node nextNode; while(currentNode!=null) { nextNode=currentNode.next; // reversing the link currentNode.next=previousNode; // moving currentNode and previousNode by 1 node previousNode=currentNode; currentNode=nextNode; } return previousNode; } 
Java program to reverse a linkedlist will be :
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 
package org.arpit.java2blog; public class LinkedList{ private Node head; private static class Node { private int value; private Node next; Node(int value) { this.value = value; } } public void addToTheLast(Node node) { if (head == null) { head = node; } else { Node temp = head; while (temp.next != null) temp = temp.next; temp.next = node; } } public void printList(Node head) { Node temp = head; while (temp != null) { System.out.format("%d ", temp.value); temp = temp.next; } System.out.println(); } // Reverse linkedlist using this function public static Node reverseLinkedList(Node currentNode) { // For first node, previousNode will be null Node previousNode=null; Node nextNode; while(currentNode!=null) { nextNode=currentNode.next; // reversing the link currentNode.next=previousNode; // moving currentNode and previousNode by 1 node previousNode=currentNode; currentNode=nextNode; } return previousNode; } public static void main(String[] args) { LinkedList list = new LinkedList(); // Creating a linked list Node head=new Node(5); list.addToTheLast(head); list.addToTheLast(new Node(6)); list.addToTheLast(new Node(7)); list.addToTheLast(new Node(1)); list.addToTheLast(new Node(2)); list.printList(head); //Reversing LinkedList Node reverseHead=reverseLinkedList(head); System.out.println("After reversing"); list.printList(reverseHead); } } 
Run above program, you will get following output:
1 2 3 4 5 
5 6 7 1 2 After reversing 2 1 7 6 5 
Recursive
1 2 3 4 5 6 7 8 9 10 11 12 
public static Node reverseLinkedList(Node node) { if (node == null  node.next == null) { return node; } Node remaining = reverseLinkedList(node.next); node.next.next = node; node.next = null; return remaining; } 
Output of this program will be same as above program.
Now lets understand logic for above recursive program.
5>6>7>1>2
Above function will terminate when last node(2)
’s next
will be null
.so while returning when you reach at node with value 1
,If you closely observe node.next.next=node
is actually setting 2>1
(i.e. reversing the link between node with value 1 and 2) and node.next=null
is removing link 1>2
. So in each iteration, you are reversing link between two nodes.
Below diagram will make it clear
Please go through java interview programs for more such programs.
That’s all about reverse a linked list in java.
I searched google like hundreds of time … but all are hazy to understand the basic concept of linkedList .. Thanks a lot .. You simply done a great job .. It is very helpful for the beginner and the people who are taking preparation for their first job… 🙂
Hi there is something wrong in the recursive function:
public static Node reverseLinkedList(Node node) {
if (node == null  node.next == null) {
return node;
}
Node remaining = reverseLinkedList(node.next);
node.next.next = node;
node.next = null;
return remaining;
}
when it reaches the last node, then how call you call node.next.next
the recursion stops in the second last node when you have the node.next = null.
Suppose I have my list as 2 4 5 6
In this case when I call 5.next = 6 then the node.next value wil be null and it will return 6 .
so the node.next.next is actually 5.next.next = 6.next which is going to be pointed to 5 .
Hope I am not confusing you. 🙂
Hello
I think that in this condition
if (node == null  node.next == null) {
return node;
}
is abit vague because you do not set the head in this recursive function. By the end of the function, the head is lost.
If i am wrong, Could you please exaplain how the function works?
this one of best website for algorithem impl. very nice implementation.