ArrayIndexOutOfBoundsException when trying to implement circular queue using arrays

Above is a diagram from the assignment page

For a homework assignment I have to implement a circular queue using arrays. I have all conditions working except for the case in which the strings "I", "J", "K", "L" are to be appended. As a result of this action, some of the new values in the array are supposed to loop back around to the beginning. However, I get the ArrayIndexOutOfBoundsException when appending the 2nd letter.

The debugger further traces the issue to the toString method, but I can't understand what the problem is.

Any advice?

public class CircularArrayQueueApp {
    public static void main(String[] args) {

        CircularArrayQueue queue = new CircularArrayQueue(10);

        String[] data1 = {"A", "B", "C", "D", "E", "F", "G", "H"};
        String[] data2 = {"I", "J", "K", "L"};

        for (String aData1 : data1) queue.enqueue(aData1);

        System.out.println(queue.first());
        System.out.println(queue);

        for (int i = 0; i < 4; i++) {
            int index = queue.getRead();
            System.out.println("\"" + queue.dequeue() + "\" has been dequeued at index " + index);
        }

        System.out.println(queue.first());
        System.out.println(queue);

        for (int i = 0; i < 4; i++) {
            queue.enqueue(data2[i]);
        }

        System.out.println(queue.first());
        System.out.println(queue);    

    }

    static class CircularArrayQueue {
        private final int length;
        private int read;
        private int write;
        private final Object[] data;

        public CircularArrayQueue(int size) {
            data = new Object[size];
            length = data.length;
            read = 0;
            write = 0;
        }

        Object read() {
            Object o;
            o = data[read];
            read = (read + 1) % length;

            return o;
        }

        Object first() {
            if (isEmpty()) {
                System.out.println("**Empty queue**");
                return null;
            }
            return data[read];
        }

        void write(Object o) {
            data[write] = o;
            write = (write + 1) % length;
        }

        boolean enqueue(Object o) {
            if (isFull()) {
                System.out.println("**Full queue**");
                return false;
            }
            write(o);
            return true;
        }

        public Object[] getData() {
            return data;
        }

        Object dequeue() {
            if (isEmpty()) {
                System.out.println("**Empty queue**");
                return null;
            }
            return read();
        }

        boolean isFull() {
            return read == (write + 1) % length;
        }

        boolean isEmpty() {
            return read == length;
        }

        public String toString() {
            String output = "[";

            for (int i = read; ((i) % length) != write; i++)
                output += data[i] + " ";

            return output.substring(0, output.length() - 1) + "]";
        }

        public int getRead() {
            return read;
        }

        public int getSize() {
            return length;
        }

        public int getWrite() {
            return write;
        }
    }
}