public class MyLinkedList<E> implements MyList<E> {
protected Node<E> head, tail;
protected int size = 0;
public MyLinkedList() {
}
public MyLinkedList(E[] objects) {
for (int i = 0; i < objects.length; i++)
add(objects[i]);
}
public E getFirst() {
if (size == 0) {
return null;
}
else {
return head.element;
}
}
public E getLast() {
if (size == 0) {
return null;
}
else {
return tail.element;
}
}
public void addFirst(E e) {
Node<E> newNode = new Node<>(e);
newNode.next = head;
head = newNode;
size++;
if (tail == null)
tail = head;
}
public void addLast(E e) {
Node<E> newNode = new Node<>(e);
if (tail == null) {
head = tail = newNode;
}
else {
tail.next = newNode;
tail = newNode;
}
size++;
}
@Override
public void add(int index, E e) {
if (index == 0) {
addFirst(e);
}
else if (index >= size) {
addLast(e);
}
else {
Node<E> current = head;
for (int i = 1; i < index; i++) {
current = current.next;
}
Node<E> temp = current.next;
current.next = new Node<>(e);
(current.next).next = temp;
size++;
}
}
public E removeFirst() {
if (size == 0) {
return null;
}
else {
E temp = head.element;
head = head.next;
size--;
if (head == null) {
tail = null;
}
return temp;
}
}
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<E> 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
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<E> previous = head;
for (int i = 1; i < index; i++) {
previous = previous.next;
}
Node<E> current = previous.next;
previous.next = current.next;
size--;
return current.element;
}
}
@Override
public String toString() {
StringBuilder result = new StringBuilder("[");
Node<E> current = head;
for (int i = 0; i < size; i++) {
result.append(current.element);
current = current.next;
if (current != null) {
result.append(", ");
}
else {
result.append("]");
}
}
return result.toString();
}
@Override
public void clear() {
size = 0;
head = tail = null;
}
@Override
public boolean contains(Object e) {
return true;
}
@Override
public E get(int index) {
return null;
}
@Override
public int indexOf(Object e) {
return 0;
}
@Override
public int lastIndexOf(E e) {
return 0;
}
@Override
public E set(int index, E e) {
return null;
}
@Override
public java.util.Iterator<E> iterator() {
return new LinkedListIterator();
}
private class LinkedListIterator
implements java.util.Iterator<E> {
private Node<E> current = head;
@Override
public boolean hasNext() {
return (current != null);
}
@Override
public E next() {
E e = current.element;
current = current.next;
return e;
}
@Override
public void remove() {
}
}
protected static class Node<E> {
E element;
Node<E> next;
public Node(E element) {
this.element = element;
}
}
@Override
public int size() {
return size;
}
}