class LinkedList implements
    Externalizable {

    public void add(final T 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++;
    }

    public  LinkedList();
    public  LinkedList(final T node);

}