Best implementation of Java Queue?

Question

I am working (in Java) on a recursive image processing algorithm that recursively traverses the pixels of the image, outwards from a center point.

Unfortunately, tha

Answer 1

Here is the Queue Implementation with Iterator and Iterable interface

Queue Size will increase as It gets full

Queue Interface

package com.practice.ds.queue;

import com.practice.ds.queue.exception.QueueException;

public interface QueueInterface {

    public boolean empty();

    public void enqueue(T item);

    public void dequeue() throws QueueException;

    public T front() throws QueueException;

    public void clear();
}

Custom Exception Class

package com.practice.ds.queue.exception;

public class QueueException extends Exception {

    private static final long serialVersionUID = -884127093599336807L;

    public QueueException() {
        super();
    }

    public QueueException(String message) {
        super(message);
    }

    public QueueException(Throwable e) {
        super(e);
    }

    public QueueException(String message, Throwable e) {
        super(message, e);
    }
}

Implementation of Queue

package com.practice.ds.queue;

import java.util.Iterator;

import com.practice.ds.queue.exception.QueueException;

public class Queue implements QueueInterface, Iterable {

    private static final int DEFAULT_CAPACITY = 10;
    private int current = 0;
    private int rear = 0;
    private T[] queueArray = null;
    private int capacity = 0;

    @SuppressWarnings("unchecked")
    public Queue() {
        capacity = DEFAULT_CAPACITY;
        queueArray = (T[]) new Object[DEFAULT_CAPACITY];
        rear = 0;
        current = 0;
    }

    @Override
    public boolean empty() {
        return capacity == current;
    }

    @Override
    public void enqueue(T item) {
        if(full())
            ensureCapacity();
        queueArray[current] = item;
        current++;
    }

    @Override
    public void dequeue() throws QueueException {
        T dequeuedItem = front();
        rear++;
        System.out.println("Dequed Item is " + dequeuedItem);
    }

    @Override
    public T front() throws QueueException {
        return queueArray[rear];
    }

    @Override
    public void clear() {
        for (int i = 0; i < capacity; i++)
            queueArray[i] = null;
        current = 0;
        rear = 0;
    }

    @SuppressWarnings("unchecked")
    private void ensureCapacity() {
        if (rear != 0) {
            copyElements(queueArray);
        } else {
            capacity *= 2;
            T[] tempQueueArray = (T[]) new Object[capacity];
            copyElements(tempQueueArray);
        }
        current -= rear;
        rear = 0;
    }

    private void copyElements(T[] array) {
        for (int i = rear; i < current; i++)
            array[i - rear] = queueArray[i];
        queueArray = array;
    }

    @Override
    public Iterator iterator() {
        return new QueueItearator();
    }

    public boolean full() {
        return current == capacity;
    }

    private class QueueItearator implements Iterator {

        private int index = rear;

        @Override
        public boolean hasNext() {
            return index < current;
        }

        @SuppressWarnings("unchecked")
        @Override
        public T next() {
            return (T) queueArray[index++];
        }
    }

}