Java Deque problem

Hey all,

This is a homework assignment regarding deques. I have it all finished and working with my inserts going from all left or all right but it doesn't work when I do both. I get this weird zero popping up and I have no clue as to what I am missing. Ive shown others in my class and they don't know. Thanks for any tips in advance!

Java Code:

//demonstrates queue
//to run this program: C>java QueueApp
////////////////////////////////////////////////////////////////

package project2;

class deque {
        private int maxSize;
        private long[] queArray;
        private int front;
        private int rear;
        private int nItems;

        // --------------------------------------------------------------
        public deque(int s) // constructor
        {
                maxSize = s;
                queArray = new long[maxSize];
                front = 0;
                rear = maxSize-1;
                nItems = 0;
        }

        // --------------------------------------------------------------
        public void insertfront(long j) // put item at rear of queue
        {
                if (isFull()){
                        System.out.println("Full cannot insert!");
                }
                if (front == 0) // deal with wraparound
                        front = maxSize-1;
                queArray[--front] = j; // increment rear and insert
                nItems++; // one more item
        }

        // --------------------------------------------------------------
        public void insertrear(long j) // put item at rear of queue
        {
                if (isFull()){
                        System.out.println("Full cannot insert!");
                }
                if (rear == maxSize-1) // deal with wraparound
                        rear = -1;
                queArray[++rear] = j; // increment rear and insert
                nItems++; // one more item
        }

        // --------------------------------------------------------------
        public long removefront() // take item from front of queue
        {
                if (isEmpty()){
                        System.out.println("Empty!");
                }
                long temp = queArray[front++];// get value and incr front
                if (front == maxSize-1) // deal with wraparound
                        front = -1;
                nItems--; // one less item
                return temp;
        }

        // --------------------------------------------------------------
        public long removerear() // take item from front of queue
        {
                if (isEmpty()){
                        System.out.println("Empty!");
                }
                long temp = queArray[rear--];// get value and incr front
                if (rear < 0) // deal with wraparound
                        rear = maxSize-1;
                nItems--; // one less item
                return temp;
        }
        //----------------------------------------------------------------
        public long remove() // take item from front of queue
        {
                long temp = queArray[front++]; // get value and incr front
                if (front == maxSize) // deal with wraparound
                        front = 0;
                nItems--; // one less item
                return temp;
        }

        // --------------------------------------------------------------
        public long peekFront() // peek at front of queue
        {
                return queArray[front];
        }

        // --------------------------------------------------------------
        public boolean isEmpty() // true if queue is empty
        {
                return (nItems == 0);
        }

        // --------------------------------------------------------------
        public boolean isFull() // true if queue is full
        {
                return (nItems == maxSize);
        }

        // --------------------------------------------------------------
        public int size() // number of items in queue
        {
                return nItems;
        }
        // --------------------------------------------------------------
        public void display() // displays array contents
        {
                for (int j = 0; j < nItems; j++) {
                long dis=queArray[(front + j) % maxSize];
                System.out.print(dis);
                System.out.print(" ");
                }
                System.out.println("");
        }
        //---------------------------------------------------------------
} // end class Queue
////////////////////////////////////////////////////////////////

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

                theQueue.insertrear(10); // insert 4 items
                theQueue.display();
                theQueue.insertrear(20);
                theQueue.display();
                theQueue.insertrear(30);
                theQueue.display();
                theQueue.insertfront(40);
                theQueue.display();

                /*theQueue.removefront(); // remove 3 items
                theQueue.display();
                theQueue.removefront(); // (10, 20, 30)
                theQueue.display();
                theQueue.removefront();
                theQueue.display();
                
                theQueue.insertfront(50); // insert 4 more items
                theQueue.display();
                theQueue.insertfront(60); // (wraps around)
                theQueue.display();
                theQueue.insertfront(70);
                theQueue.display();
                theQueue.insertfront(80);
                theQueue.display();*/

                while (!theQueue.isEmpty()) // remove and display
                { // all items
                        long n = theQueue.remove(); // (40, 50, 60, 70, 80)
                        System.out.print(n);
                        System.out.print(" ");
                }
                System.out.println("");
        } // end main()
} // end class QueueApp
////////////////////////////////////////////////////////////////

The output that I get when I do insert front, front, front, rear:



10



10 20



10 20 30



40 0 10 20



40 0 10 20