@Override
public E previous() {
if (!hasPrevious()) {
throw new NoSuchElementException("No such element.");
} else {
prevItem = head;
lastReturned = prevItem.getPrev();
prevItem = prevItem.getPrev();
head = prevItem;
index--;
return lastReturned.getData();
}
}
@Override
public E next() {
if (!hasNext()) {
throw new NoSuchElementException("No such element.");
} else {
nextItem = head;
lastReturned = nextItem;
nextItem = nextItem.getNext();
head = nextItem;
index++;
return lastReturned.getData();
}
}
@Override
public void set(E theData) { // does not work, sets data opposite where it should be
if (lastReturned == null) {
throw new IllegalStateException();
} else {
lastReturned.setData(theData);
}
}
/**
* Adds an item to the end of the list.
*
* @param data The Data that is to be stored in the node.
*/
public void add(E data) {
DoubleLinkedNode<E> newNode = new DoubleLinkedNode<E>(data);
if (this.head == null) {
newNode.setNext(newNode);
newNode.setPrev(newNode);
this.head = newNode;
size++;
// if list is empty create a new node and insert
} else {
DoubleLinkedNode<E> temp = this.head.getPrev();
this.head.getPrev().setNext(newNode);
this.head.setPrev(newNode);
newNode.setPrev(temp);
newNode.setNext(this.head);
size++;
}
}
@Override
public void add(E theData) { // adds but the old head moves to end of list
DoubleLinkedNode<E> newNode = new DoubleLinkedNode<E>(theData);
if (size == 0) {
newNode.setPrev(newNode);
newNode.setNext(newNode);
// nextItem = newNode;
// prevItem = newNode;
head = newNode;
size++;
index++;
lastReturned = null;
} else if (size != 0) {
nextItem = head;
prevItem = head.getPrev();
newNode.setNext(nextItem);
newNode.setPrev(prevItem);
nextItem.setPrev(newNode);
prevItem.setNext(newNode);
head = nextItem;
size++;
index++;
lastReturned = null;
}
}
@Override
public String toString() {
String str = "[";
int index = 0;
DoubleLinkedNode<E> curr = head;
if (size == 0) {
return "There is no one here to kill.";
} else {
while (index < size) {
str += curr.getData();
curr = curr.getNext();
index++;
if (index < size) {
str += ", ";
}
}
str += "]";
}
return str;
}
/**
* Returns the data stored at the specified index.
*
* @param index The index determines the node whose data is returned.
* @return Returns the data of the node at the index.
*/
public E get(int index) { // returns the data stored at the specified index
int currIndex = 0;
DoubleLinkedNode<E> currNode = this.head;
E temp = null;
if (index == 0) { // zero case
temp = currNode.getData();
} else if (index > 0) { // positive
while (currIndex != size) {
if (currIndex != index % size) {
currIndex++;
currNode = currNode.getNext();
} else {
temp = currNode.getData();
break;
}
}
} else if (index < 0) { // negative
while (currIndex != -size) {
if (currIndex != index % size) {
currIndex--;
currNode = currNode.getPrev();
} else {
temp = currNode.getData();
break;
}
}
}
return temp;
}
@Override
public void remove() { // removes first time but acts weird a second
if (lastReturned == null) {
throw new IllegalStateException();
}
DoubleLinkedNode<E> tempPrev = lastReturned.getPrev();
DoubleLinkedNode<E> tempNext = lastReturned.getNext();
tempPrev.setNext(tempNext);
tempNext.setPrev(tempPrev);
size--;
if (nextItem == lastReturned) {
nextItem = tempNext;
} else {
index--;
lastReturned = null;
}
}
/**
* Which adds an item at the specified index.
*
* @param index The index in which the new Node is added.
* @param data The data which is to be stored in the node.
*/
public void add(int index, E data) {
int currIndex = 0;
DoubleLinkedNode<E> currNode = this.head;
DoubleLinkedNode<E> nextNode = this.head.getNext();
DoubleLinkedNode<E> prevNode = this.head.getPrev();
DoubleLinkedNode<E> newNode = new DoubleLinkedNode<E>(data);
if (index == 0) {
prevNode.setNext(newNode);
currNode.setPrev(newNode);
newNode.setPrev(prevNode);
newNode.setNext(currNode);
this.head = newNode;
size++;
} else if (index > 0) {
while (currIndex != size) {
if (currIndex != index % size) {
currIndex++;
currNode = currNode.getNext();
nextNode = nextNode.getNext();
prevNode = prevNode.getNext();
} else {
newNode.setPrev(prevNode);
newNode.setNext(currNode);
prevNode.setNext(newNode);
currNode.setPrev(newNode);
currNode = newNode;
size++;
break;
}
}
} else if (index < 0) {
while (currIndex != -size) {
if (currIndex != index % size) {
currIndex--;
currNode = currNode.getPrev();
prevNode = prevNode.getPrev();
nextNode = nextNode.getPrev();
} else {
newNode.setNext(nextNode);
newNode.setPrev(currNode);
currNode.setNext(newNode);
nextNode.setPrev(newNode);
currNode = newNode;
size++;
break;
}
}
}
}
/**
* Which removes and returns an item from the list.
*
* @param index Removes the node at the current index.
* @return Returns the data of the removed node.
*/
public E remove(int index) { // which removes and returns an item from the list
int currIndex = 0;
DoubleLinkedNode<E> currNode = this.head;
DoubleLinkedNode<E> nextNode = this.head.getNext();
DoubleLinkedNode<E> prevNode = this.head.getPrev();
E temp = null;
if (index == 0) {
temp = currNode.getData();
prevNode.setNext(currNode.getNext());
nextNode.setPrev(currNode.getPrev());
this.head = nextNode;
size--;
} else if (index > 0) { // positive
while (currIndex != size) {
if (currIndex != index % size) {
currIndex++;
currNode = currNode.getNext();
nextNode = nextNode.getNext();
prevNode = prevNode.getNext();
} else {
temp = currNode.getData();
prevNode.setNext(currNode.getNext());
nextNode.setPrev(currNode.getPrev());
currNode = nextNode;
size--;
break;
}
}
} else if (index < 0) { // negative
while (currIndex != -size) {
if (currIndex != index % size) {
currIndex--;
currNode = currNode.getPrev();
prevNode = prevNode.getPrev();
nextNode = nextNode.getPrev();
} else {
temp = currNode.getData();
prevNode.setNext(currNode.getNext());
nextNode.setPrev(currNode.getPrev());
currNode = prevNode;
size--;
break;
}
}
}
return temp;
}