Singly LinkedList reverse algorithm using iterative and recursive methods.

LinkedListReverse.java

package algo;

public class LinkedListReverse {
    public static void main(String[] args) throws Exception {
        Node<Integer> node = new Node(1);
        node.next = new Node(2);
        node.next.next = new Node(3);
        node.next.next.next = new Node(4);
        node.next.next.next.next = new Node(5);

        System.out.println(node);
        //Node(value=1, next=Node(value=2, next=Node(value=3, next=Node(value=4, next=Node(value=5, next=null)))))
        System.out.println(reverse(node));
        //Node(value=5, next=Node(value=4, next=Node(value=3, next=Node(value=2, next=Node(value=1, next=null)))))
        System.out.println(node);
        //Node(value=1, next=Node(value=2, next=Node(value=3, next=Node(value=4, next=Node(value=5, next=null)))))
        System.out.println(reverseRecursion(node, null));
        //Node(value=5, next=Node(value=4, next=Node(value=3, next=Node(value=2, next=Node(value=1, next=null)))))
    }

    public static Node reverse(Node n) throws Exception {
        if (n == null)
            throw new Exception("Node is null");
        Node ret = null;
        while(n != null){
            Node tmp = new Node(n.value);
            ret = new Node(tmp.value, ret);
            n = n.next;
        }
        return ret;
    }

    public static Node reverseRecursion(Node n, Node tail) throws Exception {
        if(n != null){
            tail = new Node(n.value, tail);
            return reverseRecursion(n.next, new Node(tail.value, tail.next));
        }
        return tail;
    }

    private static class Node<T> {
        T value;
        Node next;

        public Node() {
        }

        public Node(T value) {
            this.value = value;
        }

        public Node(T value, Node next) {
            this.value = value;
            this.next = next;
        }

        @Override
        public String toString() {
            return "Node(value=" + this.value + ", next=" + this.next + ")";
        }
    }

}