public class Queue {
  private int maxSize;

  private int[] queArray;

  private int front;

  private int rear;

  private int nItems;

  public Queue(int s) {
    maxSize = s;
    queArray = new int[maxSize];
    front = 0;
    rear = 0;
    nItems = 0;
  }

  //   put item at the rear of a queue
  public void enqueue(int j) {
    if (!isFull()) // deal with wraparound
    queArray[rear] = j; // insert
    rear=(rear+1) % maxSize;  
    nItems++; 
  }

  //   take item from the front of queue
  public int dequeue() {
    if (isEmpty()) return 0;
    int temp = queArray[front]; // get value and incr front
    queArray[front]=0;
    front=(front+1) % maxSize;
    nItems--; // one less item
    return temp;
  }

  public int peekFront() {
    return queArray[front];
  }

  public boolean isEmpty() {
    return (nItems == 0);
  }

  public boolean isFull() {
    return (nItems == maxSize);
  }

  public int size() {
    return nItems;
  }

  public static void main(String[] args) {
    Queue theQueue = new Queue(5); // queue holds 5 items

    theQueue.enqueue(
10);
    theQueue.enqueue(20);
    theQueue.enqueue(30);
    theQueue.enqueue(40);

    theQueue.dequeue(); 
    theQueue.dequeue(); 
    theQueue.dequeue();

    theQueue.enqueue(50); 
    theQueue.enqueue(60); //    (wraps around)
    theQueue.enqueue(70);
    theQueue.enqueue(80);

    while (!theQueue.isEmpty()) {
      int n = theQueue.dequeue(); 
      System.out.print(n);
      System.out.print(" ");
    }
    System.out.println("");
  }
}