Singly Linked List operations

public class SinglyLinkedList {

       private ListNode head;

private static class ListNode {

private int data;

private ListNode next;

public ListNode(int data) {

this.data = data;

this.next = null;

}

}

// printing singly linked list

public void displayList(ListNode head) {

ListNode current = head;

while (current != null) {

System.out.println(current.data);

current = current.next;

}

}

// Reverse the linked list

public ListNode reverse(ListNode head) {

if (head == null) {

return head;

}

ListNode current = head;

ListNode previous = null;

ListNode next = null;

while (current != null) {

next = current.next;

current.next = previous;

previous = current;

current = next;

}

return previous;

}

public static void main(String[] args) {

// creating nodes

SinglyLinkedList sl = new SinglyLinkedList();

sl.head = new ListNode(10);

ListNode second = new ListNode(1);

ListNode third = new ListNode(2);

ListNode fourth = new ListNode(3);

// connecting nodes together

sl.head.next = second;

second.next = third;

third.next = fourth;

fourth.next = null;

sl.displayList(sl.head);

SinglyLinkedList.ListNode reverse = sl.reverse(sl.head);

sl.displayList(reverse);

}

}