// TODO: implement the invert method void invert() { // create a new linked list // traverse the original list, adding its elements into the new list using the "add" method // clear the original list // make head point to the head of the new linked list }

Full code:

 public class LinkedList { private Node head; public LinkedList() { head = null; } // add in front public void add(int data) { Node newNode = new Node(data); newNode.setNext(head); head = newNode; } // add tail public void append(int data) { Node newNode = new Node(data); if (isEmpty()) head = newNode; else { Node current = head; while (current.getNext() != null) current = current.getNext(); current.setNext(newNode); } } @Override public String toString() { String out = ""; Node current = head; while (current != null) { out += current.toString() + " "; current = current.getNext(); } return out; } public boolean isEmpty() { return head == null; } public int size() { int count = 0; Node current = head; while (current != null) { count++; current = current.getNext(); } return count; } public int get(int index) { if (index < 0 || index >= size()) return 0; int i = 0; Node current = head; while (i < index) { i++; current = current.getNext(); } return current.getData(); } public void set(int index, int data) { if (index < 0 || index >= size()) return; int i = 0; Node current = head; while (i < index) { i++; current = current.getNext(); } current.setData(data); } void insert(int index, int data) { if (index < 0 || index >= size()) return; if (index == 0) add(data); else { Node newNode = new Node(data); int i = 0; Node current = head; while (i < index - 1) { i++; current = current.getNext(); } newNode.setNext(current.getNext()); current.setNext(newNode); } } void remove(int index) { if (index < 0 || index >= size()) return; if (index == 0) { Node temp = head; head = head.getNext(); temp.setNext(null); } else { int i = 0; Node current = head; while (i < index - 1) { i++; current = current.getNext(); } Node temp = current.getNext(); current.setNext(current.getNext().getNext()); temp.setNext(null); } } // assume that the clear method does what it supposed to do void clear() { Node current = head; while (current != null) { Node temp = current.getNext(); current.setNext(null); current = temp; } head = null; } // TODO: implement the invert method void invert() { // create a new linked list // traverse the original list, adding its elements into the new list using the "add" method // clear the original list // make head point to the head of the new linked list } }