队列就是先进先出，没有什么难点。注意 Java 没有指针，相当于用嵌套的类模拟指针建成链表。

public class LinkedQueueOfStrings{    private class Node    {        String item;        Node next;    }    private Node first, last;    public void enqueue(String item)    {        Node oldlast = last;        last = new Node();        last.item = item;        last.next = null;        if (isEmpty()) first = last;        else oldlast.next = last;    }    String dequeue()    {        String item = first.item;        first = first.next;        if (isEmpty()) last = null;        return item;    }    boolean isEmpty()    { return first == null; }    int size()    {        int num = 0;        for(Node i = first; i != last; i = first.next)            num++;        return num + 1;    }    public static void main(String[] argv)    {        LinkedQueueOfStrings queue = new LinkedQueueOfStrings();        queue.enqueue("huangyi");        queue.enqueue("jiahai");        System.out.println(queue.dequeue());    }}

参考