ReverseLinkedList.java

class ListNode {
    int val;
    ListNode next;

    ListNode(int val) {
        this.val = val;
    }
}

public class ReverseLinkedList {
    public ListNode reverseList(ListNode head) {
        ListNode prev = null;
        ListNode current = head;

        while (current != null) {
            ListNode nextTemp = current.next;
            current.next = prev;
            prev = current;
            current = nextTemp;
        }

        return prev;
    }

    public static void main(String[] args) {
        // Create a sample linked list: 1 -> 2 -> 3 -> 4 -> 5
        ListNode head = new ListNode(1);
        head.next = new ListNode(2);
        head.next.next = new ListNode(3);
        head.next.next.next = new ListNode(4);
        head.next.next.next.next = new ListNode(5);

        ReverseLinkedList solution = new ReverseLinkedList();
        ListNode reversedHead = solution.reverseList(head);

        // Print the reversed linked list: 5 -> 4 -> 3 -> 2 -> 1
        ListNode current = reversedHead;
        while (current != null) {
            System.out.print(current.val + " -> ");
            current = current.next;
        }
        System.out.println("null");
    }
}