如何迭代和修改 Java 集? [英] How do I iterate and modify Java Sets?

问题描述

假设我有一个整数集，我想递增集合中的每个整数.我该怎么做?

Let's say I have a Set of Integers, and I want to increment every Integer in the Set. How would I do this?

我是否可以在迭代时添加和删除集合中的元素?

Am I allowed to add and remove elements from the set while iterating it?

我是否需要创建一个新集合，以便在迭代原始集合时将元素复制并修改"到其中?

Would I need to create a new set that I would "copy and modify" the elements into, while I'm iterating the original set?

如果集合的元素是不可变的怎么办?

What if the elements of the set are immutable?

推荐答案

您可以在迭代期间使用 Iterator 对象安全地从集合中移除；尝试在迭代时通过其 API 修改集合将破坏迭代器.Set 类通过 getIterator() 提供了一个迭代器.

You can safely remove from a set during iteration with an Iterator object; attempting to modify a set through its API while iterating will break the iterator. the Set class provides an iterator through getIterator().

然而，Integer 对象是不可变的；我的策略是遍历集合，对于每个整数 i，将 i+1 添加到一些新的临时集合中.完成迭代后，从原始集合中移除所有元素并添加新临时集合的所有元素.

however, Integer objects are immutable; my strategy would be to iterate through the set and for each Integer i, add i+1 to some new temporary set. When you are finished iterating, remove all the elements from the original set and add all the elements of the new temporary set.

Set<Integer> s; //contains your Integers
...
Set<Integer> temp = new Set<Integer>();
for(Integer i : s)
    temp.add(i+1);
s.clear();
s.addAll(temp);

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