Java Program to Reverse a Linked List Without Manipulating its Pointers

// Java program to reverse a linked list without pointer
// manipulation

class Node {
    int value;
    Node next;

    Node(int val)
    {
        value = val;
        next = null;
    }
}

public class LinkedList {
    Node head;

    // this function returns the Node which is at a
    // particular index.
    // (The index is passed as the argument) 
    private Node fetchNode(int index)
    {
        Node temp = head;
        for (int i = 0; i < index; i++) {
            temp = temp.next;
        }
        return temp;
    }

    // this function returns the size of linked list
    int getSize(Node head)
    {
        Node temp = head;
        int size = 0;
        while (temp != null) {
            size++;
            temp = temp.next;
        }
        return size;
    }

    // function to reverse the linked list
    void reverse()
    {
        int l = 0;
        int r = getSize(this.head) - 1;
        while (l < r) {
            Node leftSideNode = fetchNode(l);
            Node rightSideNode = fetchNode(r);

            int t = leftSideNode.value;
            leftSideNode.value = rightSideNode.value;
            rightSideNode.value = t;

            l++;
            r--;
        }
    }

    // function that prints the elements of linked list
    void printLinkedList()
    {
        Node temp = this.head;
        while (temp != null) {
            System.out.print(temp.value + " ");
            temp = temp.next;
        }
        System.out.println();
    }

    // Driver code
    public static void main(String[] args)
    {
        LinkedList list1 = new LinkedList();
        list1.head = new Node(1);
        list1.head.next = new Node(2);
        list1.head.next.next = new Node(3);
        list1.head.next.next.next = new Node(4);
        list1.head.next.next.next.next = new Node(5);

        System.out.println("Linked List Before Reversal: ");
        list1.printLinkedList();

        list1.reverse();

        System.out.println("Linked List After Reversal: ");
        list1.printLinkedList();
    }
}