Swap Nodes in the Linked List

Swap nodes in a linked list without swapping data :

 

class SwapNodes

{

  static class Node{

    int data;

    Node next;

  }

  public static void main(String[] args) {

    Node head = new Node();

     head.data = 1;

     Node node2 = new Node();

     node2.data = 2;

     Node node3 = new Node();

     node3.data = 3;

     Node node4 = new Node();

      node4.data = 4;

      Node node5 = new Node();

      node5.data = 5;

      Node node6 = new Node();

      node6.data = 6;

      Node node7 = new Node();

      node7.data = 7;

     head.next = node2;

     node2.next = node3;

     node3.next = node4;

     node4.next=node5;

     node5.next=node6;

     node6.next=node7;

     node7.next=null;

     head=swap(head,2,6);

     //head=swap(head,2,3);

     printList(head);

  }

public static Node  swap(Node head , int x , int y)

{

        if(x==y)

          return head;

        // Search for x (keep track of prevX and CurrX)

        Node prevX = null, currX = head;

        while (currX != null && currX.data != x)

        {

            prevX = currX;

            currX = currX.next;

        }

        // Search for y (keep track of prevY and currY)

       Node prevY = null, currY = head;

       while (currY != null && currY.data != y)

       {

           prevY = currY;

           currY = currY.next;

       }

       // If either x or y is not present, nothing to do

        if (currX == null || currY == null)

            return head;

            // If x is not head of linked list

            if (prevX != null)

                prevX.next = currY;

            else //make y the new head

                head = currY;

            // If y is not head of linked list

            if (prevY != null)

                prevY.next = currX;

            else // make x the new head

                head = currX;

            // Swap next pointers

            Node temp = currX.next;

            currX.next = currY.next;

            currY.next = temp;

            return head;

}

            /**

 * Print All Elements of Linked List

 *

 * @param      Head of Linked List

 */

 public static void printList(Node node) {

  Node currentNode = node;

  while (currentNode != null) {

   System.out.println(currentNode.data);

   currentNode = currentNode.next;

  }

}

}