SinglyLinkList implementation is java

public class LinkListImplementation {
 public static void main(String[] args) throws java.lang.Exception {
  LinkedListT a = new LinkedListT();
  a.addAtBegin(5);
  a.addAtBegin(15);
  a.addAtEnd(20);
  a.addAtEnd(21);
  a.deleteAtBegin();
  a.deleteAtEnd();
  a.addAtIndex(10, 2);
  a.addAtEnd(15);
  a.display();
  System.out.println("\n Size of the list is: " + a.size);
  System.out.println(" Element at 2nd position : " + a.elementAt(2));
  System.out.println(" Searching element 20, location : " + a.search(15));
 }
}

class Node {
 public int data;
 public Node next;

 public Node(int data) {
  this.data = data;
  this.next = null;
 }
}


class LinkedListT {
 public Node head;
 public int size;
 public LinkedListT() {
  head = null;
 }
 public void addAtBegin(int data) {
  Node n = new Node(data);
  n.next = head;
  head = n;
  size++;
 }
 public int deleteAtBegin() {
  int tmp = head.data;
  head = head.next;
  size--;
  return tmp;
 }
 public void deleteAtEnd() {
  Node currNode = head;
  if (head.next == null) {
   head = null;
  } else {
   while (currNode.next.next != null) {
    currNode = currNode.next;
   }
   int temp = currNode.next.data;
   currNode.next = null;
   size--;
  }
 }
 public void addAtEnd(int data) {
  if (head == null) {
   addAtBegin(data);
  } else {
   Node n = new Node(data);
   Node currNode = head;
   while (currNode.next != null) {
    currNode = currNode.next;
   }
   currNode.next = n;
   size++;
  }
 }
 public int elementAt(int index){
  if(index>size){
   return -1;
  }
  Node n = head;
  while(index-1!=0){
   n=n.next;
   index--;
  }
  return n.data;
 }
 public int getSize(){
  return size;
 }
 public int search(int data){
  Node n = head;
  int count = 1;
  while(n!=null){
   if(n.data==data){
    return count;
   }else{
    n = n.next;
    count++;
   }
  }
  return -1;
 }
 public void addAtIndex(int data, int position){
  if(position == 1){
   addAtBegin(data);
  }
  int len = size;
  if (position>len+1 || position <1){
   System.out.println("\nINVALID POSITION");
  }
  if(position==len+1){
   addAtEnd(data);
  }
  if(position<=len && position >1){
   Node n = new Node(data);
   Node currNode = head; //so index is already 1
   while((position-2)>0){
    System.out.println(currNode.data);
    currNode=currNode.next;
    position--;
   }
   n.next = currNode.next;
   currNode.next = n;
   size++;
  }
 }
 public void display() {
  System.out.println("");
  Node currNode = head;
  while (currNode != null) {
   System.out.print("->" + currNode.data);
   currNode = currNode.next;
  }
 }
}