java 如何让列表迭代器从给定的索引开始？
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How to have List Iterator start at a given index?
提问by user3769402
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:
我有一个链表，我需要创建在列表中的给定点返回迭代器的方法。我目前有一个从头开始的迭代器：
public Iterator<E> iterator( )
{
return new ListIterator();
}
All I have for the other one is:
我对另一个的所有是：
public Iterator<E> iterator(int x )
{
return new ListIterator();
}
I'm not sure how to go about utilizing the given position(x) that won't affect my ListIterator constructor which starts at head.
我不确定如何利用给定的 position(x) 不会影响我从头开始的 ListIterator 构造函数。
I 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.
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。
Edit:
编辑：
public ListIterator()
{
current = head; // head in the enclosing list
}
回答by Radiodef
Without seeing your implementation, the trivial way to do this is:
在没有看到您的实现的情况下，执行此操作的简单方法是：
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;
}
Otherwise, you could traverse the list to the xth node, but there's no reason you can't do it this way.
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。
回答by ShellFish
Simply use the listIterator(index);method from List, in which indexis an intresembling the starting index. Edit: in your case it would be
简单地使用listIterator(index);从方法List，其中index是一个int类似的起始索引。编辑：在你的情况下，它会是
List<...> list = ...;
return list.listIterator(x);
回答by user3769402
So I ended up going with this.
所以我最终选择了这个。
public Iterator<E> iterator(int x){
Iterator<E> it = new ListIterator();
for (; x > 0; --x){
it.next();
}
return it;
}
Given more range I might have added a constructor but without being able to change much this worked the best.
鉴于更大的范围，我可能已经添加了一个构造函数，但无法改变太多，这是最好的。
