public void insertAfter(final LinkedListNode existingNode, final LinkedListNode newNode) {
if (newNode.getPrevious() != null || newNode.getNext() != null) {
// do nothing if this node is already inserted somewhere
return;
}
if (existingNode == null) {
if (this.isEmpty()) {
this.firstNode = newNode;
this.lastNode = newNode;
} else {
// if existing node is null, then insert it as a first node
final LinkedListNode node = this.firstNode;
node.setPrevious(newNode);
newNode.setNext(node);
this.firstNode = newNode;
}
} else if (existingNode == this.lastNode) {
existingNode.setNext(newNode);
newNode.setPrevious(existingNode);
this.lastNode = newNode;
} else {
(existingNode.getNext()).setPrevious(newNode);
newNode.setNext(existingNode.getNext());
existingNode.setNext(newNode);
newNode.setPrevious(existingNode);
}
this.size++;
}
/**
* Add a <code>LinkedListNode</code> to the list. If the <code>LinkedList</code> is empty then the
* first and last nodes are set to the added node.
*
* @param node The <code>LinkedListNode</code> to be added
*/
public void add(final LinkedListNode node) {
if (this.firstNode == null) {
this.firstNode = node;
this.lastNode = node;
;
} else {
this.lastNode.setNext(node);
node.setPrevious(this.lastNode);
this.lastNode = node;
}
this.size++;
}
/**
* Removes a <code>LinkedListNode</code> from the list. This works by attach the previous
* reference to the child reference. When the node to be removed is the first node it calls <code>
* removeFirst()</code>. When the node to be removed is the last node it calls <code>removeLast()
* </code>.
*
* @param node The <code>LinkedListNode</code> to be removed.
*/
public void remove(final LinkedListNode node) {
if (this.firstNode == node) {
removeFirst();
} else if (this.lastNode == node) {
removeLast();
} else {
node.getPrevious().setNext(node.getNext());
(node.getNext()).setPrevious(node.getPrevious());
this.size--;
node.setPrevious(null);
node.setNext(null);
}
}
/**
* Remove the last node from the list. The previous node then becomes the last node. If this is
* the last node then both first and last node references are set to null.
*
* @return The first <code>LinkedListNode</code>.
*/
public LinkedListNode removeLast() {
if (this.lastNode == null) {
return null;
}
final LinkedListNode node = this.lastNode;
this.lastNode = node.getPrevious();
node.setPrevious(null);
if (this.lastNode != null) {
this.lastNode.setNext(null);
} else {
this.firstNode = this.lastNode;
}
this.size--;
return node;
}