如何让列表迭代器从给定的索引开始? [英] How to have List Iterator start at a given index?

问题描述

我有一个链表，我需要在列表中的给定点创建一个返回迭代器的方法.我目前有一个从头开始的迭代器:

I have a linked list and I need to make method that returns an iterator at a given point in the list. I currently have an iterator that starts at the head:

public Iterator<E> iterator( )
{
    return new ListIterator();
}

我对另一个的唯一要求是:

All I have for the other one is:

public Iterator<E> iterator(int x )
{
    return new ListIterator();
}

我不知道如何利用给定的 position(x) 不会影响我从头开始的 ListIterator 构造函数.

I'm not sure how to go about utilizing the given position(x) that won't affect my ListIterator constructor which starts at head.

我尝试使用 for 循环到达x"，但意识到这不会告诉迭代器从那里开始，所以我很困惑.

I tried using a for loop to get to "x" but realized that wouldn't tell the iterator to start there, so I'm quite stumped.

public ListIterator()
        {
            current = head; // head in the enclosing list
        }

推荐答案

在没有看到你的实现的情况下，最简单的方法是:

Without seeing your implementation, the trivial way to do this is:

public Iterator<E> iterator(int x) {
    if (x < 0 || this.size() < x) {
        throw new IndexOutOfBoundsException();
    }

    Iterator<E> it = new ListIterator();

    for (; x > 0; --x) {
        it.next(); // ignore the first x values
    }
    return it;
}

否则，您可以将列表遍历到第 x 个节点，但没有理由不能这样做.

Otherwise, you could traverse the list to the xth node, but there's no reason you can't do it this way.

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