middleLL java

// Program to find the middle node in the Linked List in a single traversal
import java.io.*;
import java.util.Scanner;
/**
 * Created by MOHIT on 25-07-2016.
 */
class ListElement{

    public int data;
    public ListElement link;
    public ListElement list1,list2;

    Scanner sc = new Scanner(System.in);
    //construtor
    ListElement(int data){
        this.data = data;
        this.link = null;
    }

    //method to update data in List element
    void updatedata(int data){
        this.data = data;
    }

    //method to setup the Link
    void setLink(ListElement node){
        this.link = node;
    }

    int getdata(){
        return this.data;
    }

    ListElement getNextNode(){
        return this.link;
    }

    //method that returns length of list
        int length(){
            ListElement node = this;
            int length_of_list = 1;

            if(node == null){
                return 0;
            }

            while(node.link != null){
                length_of_list++;
                node = node.getNextNode();
            }

            return length_of_list;
        }

    ListElement insert(ListElement head,ListElement node,int position){

        ListElement previousNode = new ListElement(head.data);
        previousNode.setLink(head.link);

        if(head == null){
            return node;
        }
        else{
            int size = length();
            if(position > size+1){
                System.out.println("Invalid position.");
                System.out.println("Valid positions are from 0 to " + size);
                return head;
            }
            if(position == 1){
                node.setLink(head);
                return node;
            }
            else if(position == 2){
                ListElement temp = new ListElement(-11);
                temp.setLink(head.link);
                head.setLink(node);
                node.setLink(temp.getNextNode());
            }
            else{
                int pos = 1;
                while(pos != position-1){
                    previousNode = previousNode.getNextNode();
                    pos++;
                }
                //ListElement temp = head.getNextNode();

                previousNode.setLink(node);
                node.setLink(null);
            }
        }
        return head;
    }

    ListElement insertAtEnd(ListElement node){
        ListElement head = this;
        int size = head.length();

        ListElement temp = this;
        while(temp.link!=null){
            temp = temp.getNextNode();
        }
        temp.setLink(node);
        return head;
    }


    void display(ListElement head){
        ListElement node = head;
        int position = 1;
        while(node!= null){
            System.out.println("Position " + position + " = " + node.data);
            position++;
            node = node.getNextNode();
        }
    }

    int middleNode(){
        ListElement Node = this;
        ListElement fast = this;
        ListElement slow = this;

        while (true){
            if(fast.getNextNode() != null){
                fast = fast.getNextNode();
                slow = slow.getNextNode();
            }else{
                break;
            }
            if(fast.getNextNode() != null){
                fast = fast.getNextNode();
            }else{
                break;
            }
        }
        return slow.getdata();
    }

    ListElement makeDummyList() {
        ListElement head = this;
        for(int i=2 ; i < 10 ; i++){
            ListElement node = new ListElement(i);
            head.insert(head,node,i);
        }
        return head;
    }

}
public class middleLL {
    public static void main(String args[]){
        Scanner sc = new Scanner(System.in);
        ListElement head = new ListElement(1);
        head.setLink(null);

        head = head.makeDummyList();
        System.out.println("The Elements of the Linked List");
        head.display(head);

        System.out.println("The Middle Element of the linked list is : " + head.middleNode());

    }
}