栈堆后进先出，队列先进后出

LinkedList<Integer> linkedList = new LinkedList<>();
        linkedList.add(1);
        linkedList.add(2);
        linkedList.add(3);
        System.out.println(linkedList);
        linkedList.add(4);
        System.out.println(linkedList);
        linkedList.pop();
        System.out.println(linkedList);

[1, 2, 3]
[1, 2, 3, 4]
[2, 3, 4]