public class ArrayQueue<E> implements QueueInterface<E> {
    private static final int CAPACITY = 1000;
    E[] queueArray;
    int front =0;
    int size=0;
    @Override
    public int size() {
	return size;
    }
    @Override
    public boolean isEmpty(){
	return size==0;
    }
    @Override
    public E first() {
	if (isEmpty()) return null;
	return queueArray[front];
    }
    @Override
    public void enqueue(E e) throws IllegalStateException {
	if (size==queueArray.length)
	    throw new IllegalStateException("Queue full");
	queueArray[(front+size)%queueArray.length] = e;
	size++;
    }
    
    @Override
    public E dequeue() {
	if (isEmpty()) return null;
	E e = queueArray[front];
	queueArray[front] = null;
	front = (front+1)%queueArray.length;
	size--;
	return e;
    }
    public ArrayQueue() {
	this(CAPACITY);
    }  
    @SuppressWarnings("unchecked")
    public ArrayQueue(int capacity) {
	queueArray = (E[])new Object[capacity];
    }
    
    public String toString()
    {
	StringBuffer sb = new StringBuffer();
	sb.append("Siz:");
	sb.append(size);
	sb.append("  Fnt:");
	sb.append(front);
	sb.append(" (");
	for (int i=front; i<(front+size); i++)
	{
	    sb.append(queueArray[i]);
	    if (i<(front+size-1))
		sb.append(", ");
	}
	sb.append(")");
	return sb.toString();
	
    }
    public static void main(String[] args)
    {
	ArrayQueue<Integer> qqq = new ArrayQueue<>();
	qqq.enqueue(2);
	System.out.println(qqq);
	qqq.enqueue(3);
	System.out.println(qqq);
	qqq.dequeue();
	System.out.println(qqq);
	qqq.enqueue(7);
	System.out.println(qqq);
	qqq.dequeue();
	System.out.println(qqq);
	System.out.println("First:"+qqq.first());
	qqq.dequeue();
	System.out.println(qqq);
	qqq.dequeue();
	System.out.println("Empty: " + qqq.isEmpty());
	qqq.enqueue(9);
	System.out.println(qqq);
	qqq.enqueue(7);
	System.out.println(qqq);
	System.out.println("Size: " + qqq.size());
	qqq.enqueue(3);
	System.out.println(qqq);
	qqq.enqueue(5);
	System.out.println(qqq);
	qqq.dequeue();
	System.out.println(qqq);
    }


}