linked-list.java

public class LinkedList {

    private Node head;
    private Node current;
    private boolean isFirst = false;
    private int length;

    public LinkedList() {

    }

    public LinkedList(Node head) {
        this.head = head;

    }

    public Node reverse(Node headElement, int k) {

        Node current = headElement;
        Node previous = null;
        Node next = null;
        int count = 0;

        while (current != null && count < k) {
            next = current.getNext();
            current.setNext(previous);
            previous = current;
            current = next;
            count++;
        }

        if (null != next && this.length - count > k) {
            headElement.setNext(reverse(next, k));
        }else{

            Node tail = previous;
            while(tail != null){
                if(tail.getNext() !=null){
                    tail = tail.getNext();
                }else{
                    break;
                }

            }
            tail.setNext(current);


        }

        return previous;
    }


    public Node reverse() {
        Node current = head;
        Node previous = null;
        Node next = null;

        while (current != null) {
            next = current.getNext();
            current.setNext(previous);
            previous = current;
            current = next;
        }
        head = previous;
        return previous;
    }

    public void add(int data) {
        this.length++;
        boolean isStart = false;
        if (null == head) {
            isStart = true;
            head = new Node(data);
        }

        Node n = new Node(data);

        if (null == current && !isStart) {
            head.setNext(n);
            current = n;
            isFirst = false;
            return;
        }

        if (null != current) {
            while (current.getNext() != null) {
                current = current.getNext();
            }
            current.setNext(n);

        }


    }

    public void display() {
        Node current = head;
        while (current != null) {
            System.out.print(String.format("%s ->", current.getData()));
            current = current.getNext();
        }
        System.out.println("-----");
    }

    public static void main(String[] args) {
        LinkedList linkedList = new LinkedList();

        linkedList.add(1);
        linkedList.add(2);
//        linkedList.add(3);
//        linkedList.add(4);
//        linkedList.add(5);
        linkedList.display();
        linkedList.reverse();
//        linkedList.head = linkedList.reverse(linkedList.head, 3);
        linkedList.display();


    }
}

class Node {

    private final int data;

    public void setNext(Node next) {
        this.next = next;
    }

    public int getData() {
        return data;

    }

    public Node getNext() {
        return next;
    }

    private Node next = null;

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

}