ArrayQueue.java

//Benjamin Maymir
//maymi001

//  ARRAY QUEUE. A fixed length queue represented as a circular array.

class ArrayQueue<Base>
{
  private int    front;    //  Index of front object in OBJECTS.
  private int    rear;     //  Index of rear object in OBJECTS.
  public Base[] objects;  //  The OBJECTs in the queue.

//  Constuctor. Make a new empty queue that can hold SIZE - 1 elements.

  public ArrayQueue(int size)
  {
    if (size <= 1)
    {
      throw new IllegalArgumentException("Illegal size.");
    }
    else
    {
      front   = 0;
      rear    = 0;
      objects = (Base []) new Object[size];
    }
  }

//  DEQUEUE. Remove an object from the queue.

  public Base dequeue()
  {
    if (front == rear)
    {
      throw new IllegalStateException("Queue is empty.");
    }
    else
    {
      front = (front + 1) % objects.length;
      Base temp = objects[front];
      objects[front] = null;
      return temp;
    }
  }

//  ENQUEUE. Add a new OBJECT to the queue.

  public void enqueue(Base object)
  {
    int nextRear = (rear + 1) % objects.length;
    if (front == nextRear)
    {
      throw new IllegalStateException("Queue is full.");
    }
    else
    {
      rear = nextRear;
      objects[rear] = object;
    }
  }

//  IS EMPTY. Test if the queue is empty.

  public boolean isEmpty()
  {
    return front == rear;
  }

//  IS FULL. Test if the queue is full.

  public boolean isFull()
  {
    return front == (rear + 1) % objects.length;
  }
  public Iterator iterator(){
    return new Iterator();
  }
  public class Iterator{
    private int position;
    private Iterator(){ 
      position=front;
    }
    public boolean hasNext(){
      return (position)%objects.length!=rear;
    }
    public Base next(){
      position=(position+1)%objects.length;
      return objects[(position)];
    }
  }
}