I need help completing some of the methods in this Java Class file. More Specifically the methods that have a comment "left as an exercise".

public class MyLinkedList implements MyList { protected Node head, tail; protected int size = 0; // Number of elements in the list /** Create an empty list */ public MyLinkedList() { } /** Create a list from an array of objects */ public MyLinkedList(E[] objects) { for (int i = 0; i < objects.length; i++) add(objects[i]); } /** Return the head element in the list */ public E getFirst() { if (size == 0) { return null; } else { return head.element; } } /** Return the last element in the list */ public E getLast() { if (size == 0) { return null; } else { return tail.element; } } /** Add an element to the beginning of the list */ public void addFirst(E e) { Node newNode = new Node<>(e); // Create a new node newNode.next = head; // link the new node with the head head = newNode; // head points to the new node size++; // Increase list size if (tail == null) // the new node is the only node in list tail = head; } /** Add an element to the end of the list */ public void addLast(E e) { Node newNode = new Node<>(e); // Create a new for element e if (tail == null) { head = tail = newNode; // The new node is the only node in list } else { tail.next = newNode; // Link the new with the last node tail = newNode; // tail now points to the last node } size++; // Increase size } @Override /** Add a new element at the specified index * in this list. The index of the head element is 0 */ public void add(int index, E e) { if (index == 0) { addFirst(e); } else if (index >= size) { addLast(e); } else { Node current = head; for (int i = 1; i < index; i++) { current = current.next; } Node temp = current.next; current.next = new Node<>(e); (current.next).next = temp; size++; } } /** Remove the head node and * return the object that is contained in the removed node. */ public E removeFirst() { if (size == 0) { return null; } else { E temp = head.element; head = head.next; size--; if (head == null) { tail = null; } return temp; } } /** Remove the last node and * return the object that is contained in the removed node. */ public E removeLast() { if (size == 0) { return null; } else if (size == 1) { E temp = head.element; head = tail = null; size = 0; return temp; } else { Node current = head; for (int i = 0; i < size - 2; i++) { current = current.next; } E temp = tail.element; tail = current; tail.next = null; size--; return temp; } } @Override /** Remove the element at the specified position in this * list. Return the element that was removed from the list. */ public E remove(int index) { if (index < 0 || index >= size) { return null; } else if (index == 0) { return removeFirst(); } else if (index == size - 1) { return removeLast(); } else { Node previous = head; for (int i = 1; i < index; i++) { previous = previous.next; } Node current = previous.next; previous.next = current.next; size--; return current.element; } } @Override /** Override toString() to return elements in the list */ public String toString() { StringBuilder result = new StringBuilder("["); Node current = head; for (int i = 0; i < size; i++) { result.append(current.element); current = current.next; if (current != null) { result.append(", "); // Separate two elements with a comma } else { result.append("]"); // Insert the closing ] in the string } } return result.toString(); } @Override /** Clear the list */ public void clear() { size = 0; head = tail = null; } @Override /** Return true if this list contains the element e */ public boolean contains(Object e) { // Left as an exercise return true; } @Override /** Return the element at the specified index */ public E get(int index) { // Left as an exercise return null; } @Override /** Return the index of the first matching element in * this list. Return -1 if no match. */ public int indexOf(Object e) { // Left as an exercise return 0; } @Override /** Return the index of the last matching element in * this list. Return -1 if no match. */ public int lastIndexOf(E e) { // Left as an exercise return 0; } @Override /** Replace the element at the specified position * in this list with the specified element. */ public E set(int index, E e) { // Left as an exercise return null; } @Override /** Override iterator() defined in Iterable */ public java.util.Iterator iterator() { return new LinkedListIterator(); } private class LinkedListIterator implements java.util.Iterator { private Node current = head; // Current index @Override public boolean hasNext() { return (current != null); } @Override public E next() { E e = current.element; current = current.next; return e; } @Override public void remove() { // Left as an exercise } } protected static class Node { E element; Node next; public Node(E element) { this.element = element; } } @Override /** Return the number of elements in this list */ public int size() { return size; } }