我可以使用 java.util.LinkedList 来构造循环/循环链表吗? [英] Can I use java.util.LinkedList to construct a circular/cyclic linked list?

问题描述

我想创建一个循环/循环链表，其中列表的尾部将指向列表的头部.那么我可以使用 java.util.LinkedList 并在创建列表后修改尾节点以使其循环/循环吗?如果是这样，你能告诉我一些关于如何发生的代码吗?

I would like to create a circular/cyclic linked list where the tail of the list would point back to the head of the list. So can I use java.util.LinkedList and modify the tail node after creation of the list to make it circular/cyclic? If so, can you show me some code on how that would happen?

如果我不能使用 java.util.LinkedList，我应该如何创建自己的循环/循环链表实现?你能告诉我这个实现的框架吗?

If I can't use java.util.LinkedList, how should I create my own circular/cyclic linked list implementation? Can you show me the skeletons of how this implementation would look?

如果您需要更多详细信息，请告诉我，我会消除任何困惑.

Let me know if you need more details and I'll clear up any confusion.

推荐答案

class ListNode {
    public ListNode next;
    public Object data;

    public ListNode(Object data, ListNode next) {
        this.next = next;
        this.data = data;
    }
}

class CircularLinkedList {
    private ListNode head = null;
    private int numberOfElements = 0;
    private ListNode actualElement = null;
    private int index = 0;

    public boolean isEmpty() {
        return (numberOfElements == 0);
    }

    public int getNumberOfElements() {
        return numberOfElements;
    }

    public void insertFirst(Object data) {
        if (!(isEmpty())) {
            index++;
        }
        ListNode listNode = new ListNode(data, head);
        head = listNode;
        numberOfElements++;
    }

    public void insertAfterActual(Object data) {
        ListNode listNode = new ListNode(data, actualElement.next);
        actualElement.next = listNode;
        numberOfElements++;
    }

    public boolean deleteFirst() {
        if (isEmpty())
            return false;
        if (index > 0)
            index--;
        head = head.next;
        numberOfElements--;
        return true;
    }

    public boolean deleteActualElement() {
        if (index > 0) {
            numberOfElements--;
            index--;
            ListNode listNode = head;
            while (listNode.next.equals(actualElement) == false)
                listNode = listNode.next;
            listNode.next = actualElement.next;
            actualElement = listNode;
            return true;
        }
        else {
            actualElement = head.next;
            index = 0;
            return deleteFirst();
        }
    }

    public boolean goToNextElement() {
        if (isEmpty())
            return false;
        index = (index + 1) % numberOfElements;
        if (index == 0)
            actualElement = head;
        else
            actualElement = actualElement.next;
        return true;
    }

    public Object getActualElementData() {
        return actualElement.data;
    }

    public void setActualElementData(Object data) {
        actualElement.data = data;
    }
}

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