K Reverse In Linked List

I/O:

11

1 2 3 4 5 6 7 8 9 10 11

3

100

200

O/P:

1 2 3 4 5 6 7 8 9 10 11 3 2 1 6 5 4 9 8 7 10 11 100 3 2 1 6 5 4 9 8 7 10 11 200

import java.io.BufferedReader;
import java.io.InputStreamReader;

public class K_Reverse_In_LinkedList {
    public static class Node {
        int data;
        Node next;
    }

    public static class LinkedList {
        Node head;
        Node tail;
        int size;

        void addLast(int val) {
            Node temp = new Node();
            temp.data = val;
            temp.next = null;

            if (size == 0) {
                head = tail = temp;
            } else {
                tail.next = temp;
                tail = temp;
            }

            size++;
        }

        public int size() {
            return size;
        }

        public void display() {
            for (Node temp = head; temp != null; temp = temp.next) {
                System.out.print(temp.data + " ");
            }
            System.out.println();
        }

        public void removeFirst() {
            if (size == 0) {
                System.out.println("List is empty");
            } else if (size == 1) {
                head = tail = null;
                size = 0;
            } else {
                head = head.next;
                size--;
            }
        }

        public void addFirst(int val) {
            Node temp = new Node();
            temp.data = val;
            temp.next = head;
            head = temp;

            if (size == 0) {
                tail = temp;
            }

            size++;
        }

        // write your code here
        public void kReverse(int k) {
            LinkedList ans = new LinkedList();

            while (k < size) {
                LinkedList current = new LinkedList();
                for (int i = 0; i < k; i++) {
                    current.addFirst(head.data);
                    this.removeFirst();
                }

                if (ans.size == 0) {
                    ans.head = current.head;
                    ans.tail = current.tail;
                    ans.size = current.size;
                } else {
                    ans.tail = current.head;
                    ans.tail = current.tail;
                    ans.size += current.size;
                }
            }

            while (size > 0) {
                ans.addLast(head.data);
                this.removeFirst();
            }
            head = ans.head;
            tail = ans.tail;
            this.size = ans.size;
        }
    }

    public static void main(String[] args) throws Exception {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        int n1 = Integer.parseInt(br.readLine());
        LinkedList l1 = new LinkedList();
        String[] values1 = br.readLine().split(" ");
        for (int i = 0; i < n1; i++) {
            int d = Integer.parseInt(values1[i]);
            l1.addLast(d);
        }

        int k = Integer.parseInt(br.readLine());
        int a = Integer.parseInt(br.readLine());
        int b = Integer.parseInt(br.readLine());

        l1.display();
        l1.kReverse(k);
        l1.display();
        l1.addFirst(a);
        l1.addLast(b);
        l1.display();
    }
}