In java, for a doubly linked list, how can I make this add in alphabetical order

/**

* adds element at the starting of the linked list

*

* @param element

*/

public void add(String element) {

Node tmp = new Node(element, head, null);

if (head != null) {

head.prev = tmp;

}

head = tmp;

if (tail == null) {

tail = tmp;

}

size++;

}