LinkedQueue Code:

public class LinkedQueue implements QueueADT {

private LNode front; private LNode rear; private int size;

public LinkedQueue() { front = null; rear = null; size = 0; }

@Override public void enqueue(T element) { // TODO Auto-generated method stub

LNode newNode = new LNode(element); if (isEmpty()) { rear = newNode; front = newNode; } else { rear.setNext(newNode); rear = newNode; } size++; }

@Override public T dequeue() { // TODO Auto-generated method stub T retData; if (isEmpty()) { throw new EmptyCollectionException("linked queue"); } else {

retData = front.getData(); front = front.getNext(); size--; return retData; } }

@Override public T first() { // TODO Auto-generated method stub if (isEmpty()) { throw new EmptyCollectionException("linked queue"); } else {

return front.getData(); } }

@Override public boolean isEmpty() { // TODO Auto-generated method stub return (size == 0); }

@Override public int size() { // TODO Auto-generated method stub return size; }

public String toString() { String retString = "["; LNode it = front; while (it != null) { retString += it.getData(); retString += " "; it = it.getNext(); } retString += "]"; return retString; }

}

QueueADT:

public interface QueueADT {

public void enqueue(T element); public T dequeue(); public T first(); public boolean isEmpty(); public int size(); }

+ indexOf(T element): int - Returns the index of the first occurrence of the specified element in this queue from the front, or -1 if this queue does not contain the element. The element at the front is at index 0