LinkedList：删除一个对象 [英] LinkedList: remove an object

问题描述

这是使用for循环在Java中从LinkedList中查找和删除项目的有效方法，是否可能出现不一致：

Is this a valid way to find and remove item from a LinkedList in Java using a for each loop, is it possible that inconsistency may arise:

for(ObjectType ob : obList) {
  if(ob.getId() == id) {
    obList.remove(ob);
    break;
   }
}

推荐答案

其他已经提到了有效点，通常这不是你如何从集合中删除对象。但是，在这种情况下，一旦你删除，打破就可以了。

Others have mentioned the valid point that normally this is not how you remove an object from a collection. HOWEVER, in this case it's fine since you break out of the loop once you remove.

但是，如果要在 remove 之后继续迭代，则需要使用迭代器。否则你将得到一个 ConcurrentModificationException ，或者在更一般的情况下，得到未定义的行为。

If you want to keep iterating after a remove, though, you need to use an iterator. Otherwise you'll get a ConcurrentModificationException, or in the more general case, undefined behavior.

所以是的，如果您在删除之后中断 >，你会没事的。

So yes, if you break out of the foreach after you remove, you'll be fine.

对于那些说这会失败的人，因为你可以'修改 foreach 中的集合 - 只有当你想继续迭代时才会这样。这不是这种情况，所以这个快捷方式很好。

To those who's saying that this will fail because you can't modify a collection in a foreach -- this is true only if you want to keep iterating. That's not the case here, so this shortcut is fine.

迭代器检查并抛出一个 ConcurrentModificationException 。这里，在 remove （符合并发修改条件）之后，你中断了。迭代器甚至没有机会检测它。

A ConcurrentModificationException is checked and thrown by the iterator. Here, after the remove (which qualifies as concurrent modification), you break out of the loop. The iterator doesn't even get a chance to detect it.

最好是在中断，为什么它是绝对必要的等等，因为如果稍后修改此代码以在 remove 之后继续迭代，它将失败。

It may be best if you add a comment on the break, why it's absolutely necessary, etc, because if this code is later modified to continue iterating after a remove, it will fail.

我会把这个成语看作类似于 goto （或者更确切地说，标记为 break / 继续）：一开始可能看起来不对，但是明智地使用它会使代码更清晰。

I would treat this idiom similar to goto (or rather, labeled break/continue): it may seem wrong at first, but when used wisely, it makes for a cleaner code.

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