reverse singly list recursively and iteratively

SinglyListNode.java

public class SinglyListNode {

    SinglyListNode next;
    String s;

    public String toString(){return s;}
    public SinglyListNode(String s){this.s=s;}

    public static void main(String argsp[]){
        
        SinglyListNode a = new SinglyListNode("a");
        SinglyListNode b = new SinglyListNode("b");
        SinglyListNode c = new SinglyListNode("c");


        a.next = b;
        b.next = c;

        p(a);
        SinglyListNode e =recursiveReverse(a, null);
        p(e);

        SinglyListNode f = iterativeReverse(e);
        p(f);
    }

    public static void p(SinglyListNode n){
        if (n==null) return;
        System.out.print(n);
        p(n.next);
    }



    public static SinglyListNode iterativeReverse(SinglyListNode n){
        SinglyListNode previous = null;
        SinglyListNode current = n;
        while (current!=null){
            SinglyListNode tmp = current.next;
            current.next = previous;
            previous = current;
            current = tmp;
        }
        return previous;
    }

    public static SinglyListNode recursiveReverse(SinglyListNode a, SinglyListNode previous){


        if (a.next==null){
            a.next = previous;
            return a;
        }else {
            SinglyListNode b = a.next;
            a.next = previous;

            return recursiveReverse(b, a);

        }

    }
}