public static void main(String[] args) {
        Queue<String> queue = new Queue<String>();
        queue.enqueue("zhu");
        queue.enqueue("zhen");
        queue.enqueue("guang");

        for (String s : queue) {
            StdOut.println(s);
        }

        StdOut.println("========================");

        StdOut.println(queue.dequeue());

        StdOut.println("========================");

        for (String s : queue) {
            StdOut.println(s);
        }

        StdOut.println("========================");

        StdOut.println(queue.size());

        Iterator<String> it = queue.iterator();
        while (it.hasNext())
            it.remove();

        StdOut.println(queue.size());
    }