循环双链表indexOf和remove函数不正确

Question

我目前正在实现一个带有虚拟头部节点的循环双链表。我的add函数（在给定索引、开始或结束时添加一个元素）似乎可以完美地工作，但我无法推断出一个有效的indexOf（返回元素的索引）或remove（在给定索引处删除节点）方法。

调试时，indexOf似乎获取了错误的索引。当给出以下列表时：

[Alabama, Alaska, Arizona, Arkansas, Wyoming, California]

使命感

list.remove(indexOf("Wyoming"));

回报

[Alabama, Alaska, Arizona, Arkansas, Wyoming, ]

以下是indexOf函数：

public int indexOf(E e) {
    Node<E> current = head;
    for (int i = 0; i < size; i++) {
        if (e.equals(current.element)) {
            return i;
        }
        current = current.next;
    }
    return -1;
}

这里是删除函数：

public E remove(int index) {
    if (index < 0 || index >= size) {
        throw new NoSuchElementException();
    } else if (index == 0) {
        return removeFirst();
    } else if (index == size - 1) {
        return removeLast();
    } else {


        Node<E> previous = head;
        for (int i = 1; i < index; i++) {
            previous = previous.next;
        }
        Node<E> current = previous.next;
        previous.next = current.next;
        size--;
        return current.element;

    }
}

Answer 1

如果head应该始终为null，那么您的indexOf（）方法似乎不正确

public int indexOf(E e) {
    Node<E> current = head.next; // Add this to effectively begin with the first index of your list
    for (int i = 0; i < size; i++) {
        if (e.equals(current.element)) { // This will never be equals, because of the first time current being null
            return i;
        }
        current = current.next;
    }
    return -1;
}