Reverse a linked List (iterative and recursive way)

// iterative

public ListNode reverse(ListNode head) {

    if(head == null) {

        return head;
    }

    ListNode prev = null;

    while(head != null) {

        ListNode nextNode = head.next;

        head.next = prev;

        prev = head;

        head = nextNode;

    }

    return prev;
}

// recursive

public ListNode reverse2(ListNode head) {

    if(head == null || head.next == null) {

        return head;

    }

    ListNode nextNode = head.next;

    ListNode newHead = reverse2(nextNode);

    nextNode.next = head;

    head.next =  null;

    return newHead;

}