Linked List Insertion and Deletion in Java

import java.lang.*;

// Node Class
class Node {
    int data;
    Node next;

    Node(int x) // parameterized constructor
    {
        data = x;
        next = null;
    }
}

class Main
{
    public static Node deleteStart(Node head)
    {
        if (head == null){
            System.out.println("List is empty, not possible to delete");
            return head;
        }

        System.out.println("Deleted: " + head.data);
        // move head to next node
        head = head.next;

        return head;
    }
    static Node deleteLast(Node head) {
        if (head == null){
            System.out.println("List is empty, not possible to delete");
            return head;
        }

        // if LL has only one node
        if(head.next == null)
        {
            System.out.println("Deleted: " + head.data);
            head = head.next;
            return head;
        }
        Node previous = null;
        Node temp = head;
        // else traverse to the last node
        while (temp.next != null)
        {
            // store previous link node as we need to change its next val
            previous = temp;
            temp = temp.next;
        }
        // Curr assign 2nd last node's next to Null
        System.out.println("Deleted: " + temp.data);
        previous.next = null;
        // 2nd last now becomes the last node

        return head;
}

    static Node deletePosition(int n, Node head) {
        int size = calcSize(head);

        // Can only insert after 1st position
        // Can't insert if position to insert is greater than size of Linked List
        if(n < 1 || n > size)
            System.out.println("Can't delete\n");

        else
        {
            if(n == 1)
            {
                // head has to be deleted
                System.out.println("Deleted: " + head.data);
                head = deleteStart(head);
                return head;
            }
            // required to traverse
            Node temp = head;
            Node previous = null;

            // traverse to the nth node
            while(--n > 0) {
                previous = temp;
                temp = temp.next;
            }
            // assigned next node of the previous node to nth node's next
            previous.next = temp.next;
            System.out.println("Deleted: " + temp.data);
            }
        return head;
    }
    public static Node insert(Node head, int data)
    {
        // Creating newNode memory & assigning data value
        Node newNode = new Node(data);
        // assigning this newNode's next as current head node
        newNode.next = head;

        // re-assigning head to this newNode
        head = newNode;

        return head;
    }
    static void display(Node node) {

        //as linked list will end when Node is Null
        while (node != null) {
            System.out.print(node.data + " ");
            node = node.next;
        }
        System.out.println("\n");
    }

    // required for insertPosition() method
    static int calcSize(Node node){
        int size=0;

        // traverse to the last node each time incrementing the size
        while(node!=null)
        {
            node = node.next;
            size++;
        }
        return size;
    }

    public static void main(String args[])
    {
        Node head = null;

        head = insert(head, 6);
        head = insert(head, 5);
        head = insert(head, 4);
        head = insert(head, 3);
        head = insert(head, 2);
        head = insert(head, 1);
        display(head);

        head = deleteStart(head);
        display(head);

        head = deleteLast(head);
        display(head);

        // deletes 3rd node
        head = deletePosition( 3, head);
        display(head);

    }
}