Java program to check whether linked list is palindrome or not

import java.util.*;

public class Main
{

  public static void main (String[]args) throws Exception
  {
    LinkedList ll = new LinkedList ();
      ll.addFirst (10);
      ll.addFirst (20);
      ll.addFirst (30);
      ll.addFirst (40);
      ll.addFirst (40);
      ll.addFirst (30);
      ll.addFirst (20);
      ll.addFirst (10);

      ll.display ();

      System.out.println (ll.isPalindrome ());

  }

}

class LinkedList
{
  private class Node
  {
    int data;
    Node next;

// Node constructor
// There are two fields in the node- data and address of next node
    public Node (int data, Node next)
    {
      this.data = data;
      this.next = next;
    }
  }

  private Node head;
  private Node tail;
  private int size;

// Linked list constructor
  public LinkedList ()
  {
    this.head = null;
    this.tail = null;
    this.size = 0;

  }

// Function to find the size of linked list
  public int size ()
  {
    return this.size;
  }

// Function to check whether linked list is empty or not
  public boolean isEmpty ()
  {
    return this.size () == 0;
  }

// Function to traverse and print the linked list
  public void display ()
  {
    Node temp = head;
    while (temp != null)
      {
	System.out.print (temp.data + "  ");

	temp = temp.next;
      }
    System.out.println ("END");
  }

// Function to add a node in beginning of linked list
  public void addFirst (int item)
  {
// Create a temp node which points to head
    Node temp = new Node (item, head);

// If linked list is empty, temp is the head and tail node both
    if (this.size == 0)
      {
	this.head = this.tail = temp;
      }

// else set the head such that it now points to temp node
    else
      {
	this.head = temp;

      }

    this.size++;
  }

  public boolean isPalindrome ()
  {
    HeapMover start = new HeapMover ();

    start.node = this.head;

    return this.isPalindrome (start, this.head, 0);

  }

//Function to check whether linked list is palindrome or not
  private boolean isPalindrome (HeapMover start, Node end, int floor)
  {

//Base case is when we reach end of linked list
    if (end == null)
      {
	return true;
      }

//Recursive calls
    boolean rv = this.isPalindrome (start, end.next, floor + 1);

//If any recursive call results in false then return false
    if (rv == false)
      {
	return false;
      }

//Till floor is greater than 1/2 * size of linked list
    if (floor >= this.size () / 2)
      {

//If data of start node and end node is not same then it is not palindrome
	if (start.node.data != end.data)
	  {
	    return false;

	  }

//Change start node so that it now points to the next node
	else
	  {
	    start.node = start.node.next;
	    return true;
	  }

      }
    return rv;

  }

//Class to keep a node in the heap
  private class HeapMover
  {
    Node node;
  }

}

Output: 
10  20  30  40  40  30  20  10  END
true