public void add(int index, E element) {
if (index < 0 || index > size) {
throw new IndexOutOfBoundsException("Index out of bounds: " + index);
} else if (element == null) {
throw new NullPointerException("Null elements not supported by list.");
} else if (index == 0) {
final LLNode<E> node = new LLNode<>(element);
node.setNext(head);
head.setPrev(node);
head = node;
size++;
} else if (index == size) {
final LLNode<E> node = new LLNode<>(element);
tail.setNext(node);
node.setPrev(tail);
tail = node;
size++;
} else {
final LLNode<E> node = new LLNode<>(element);
LLNode<E> nextNode = new LLNode<>(null);
nextNode = head;
while (index > 0) {
nextNode = nextNode.next;
index--;
}
nextNode.prev.next = node;
node.prev = nextNode.prev;
node.next = nextNode;
nextNode.prev = node;
size++;
}
// This method adds an element at the specified index.
// If elements exist at that index, you will move elements at that
// index (and beyond) up, effectively inserting this element at that location in the list.
// Although drawings are helpful for implementing any method, you will benefit heavily from
// drawing out what should happen in this method before trying to code it.
// You will want to throw an IndexOutOfBoundsException if the index provided is not reasonable
// for
// inserting an element.
// Optional: After authoring this version of the add method, you could consider removing
// redundant
// code by having the add method you originally wrote just call this method.
// To test this method, use the method in MyLinkedListTester called testAddAtIndex.
}
/** Create a new empty doublyLinkedList */
public MyLinkedList() {
this.size = 0;
this.head = new LLNode<E>(null);
this.tail = new LLNode<E>(null);
// Set the initial references
head.setNext(tail);
tail.setPrev(head);
}