用Iterator循环时将项目添加到HashMap [英] Adding items to a HashMap while looping with Iterator

问题描述

我有一个使用迭代器循环访问HashMap的程序，在循环内部，我添加了HashMap - 这导致了ConcurrentModificationException异常。我已经看到ListIterator有一个add（）函数来处理这个，但Iterator没有。

I have a program that loops through a HashMap using an Iterator, and inside the loop, I'm adding to the HashMap - which is causing a ConcurrentModificationException. I've seen that ListIterator has an add() function that handles this, but Iterator does not.

HashMap是这样设置的 -

The HashMap is set up like this -

HashMap<Pair<Integer, Integer>, Object>

迭代器像这样 -

Iterator<Entry<Pair<Integer, Integer>, Object>> iter;

使用Object（不是真名）是我程序中的一个类。
有人知道如何在循环或任何其他选项时添加到迭代器吗？

With Object (not the real name) being a class from my program. Does anybody know how I can go about adding to the iterator while I'm looping or any other options?

推荐答案

改为循环显示地图的副本，然后添加到原始地图中。地图的输入集是Map的键值对的视图，并且不支持添加，但您可以移除项目。

Loop through a copy of the map instead, and add to the original map. The entry set of a map is a view of the Map's key value pairs, and does not support addition though you can remove items.

或者，您可以将元素添加到新的然后迭代地图，然后使用 putAll（） ...来想一想，这可能更有效率。

Alternatively you can add elements to a new map while iterating and then use putAll() afterwards ... come to think of it, that is probably more efficient.

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