/**
    * Constructs an empty list.
    */
public LinkedList() {
}

/**
    * Constructs a list containing the elements of the specified
    * collection, in the order they are returned by the collection's
    * iterator.
    *
    * @param  c the collection whose elements are to be placed into this list
    * @throws NullPointerException if the specified collection is null
    */
public LinkedList(Collection<? extends E> c) {
    this();
    addAll(c);
}

public static void main(String[] args) {
        Queue<String> queue = new LinkedList<String>();
        initQueue(queue);
        for(String q : queue){
            System.out.print(q+"\t");
        }
        System.out.print("\n");
        System.out.println(" 队列中头信息element: "+queue.element());
        System.out.println(" 获取信息poll: " + queue.poll());
        System.out.println(" 队列中头信息element: "+queue.element());
        System.out.println(" ============ ");
        System.out.println(" 队列中头信息peek: "+queue.peek());

        for(String q : queue){
            System.out.print(q+"\t");
        }
        System.out.print("\n");
    }

    /** 初始化队列中的数据
     * @Description
     * @param queue
     * @return void
     * @throws
     * @date 2020/8/5 15:12
     */
    public static void initQueue(Queue<String> queue){
        queue.offer("Q1");
        queue.offer("Q2");
        queue.offer("Q3");
        queue.offer("Q4");
        queue.offer("Q5");
    }