在迭代列表时将元素添加到列表中.(爪哇)

You can't modify a Collection while iterating over it using an Iterator, except for Iterator.remove().

但是，如果您使用 listIterator() 方法，它返回一个 ListIterator，并迭代你有更多的选项可以修改.来自 add() 的 javadoc:

However, if you use the listIterator() method, which returns a ListIterator, and iterate over that you have more options to modify. From the javadoc for add():

新元素被插入到隐式游标之前:... 对 previous() 的后续调用将返回新元素

The new element is inserted before the implicit cursor: ... a subsequent call to previous() would return the new element

鉴于此，这段代码应该可以将新元素设置为迭代中的下一个:

Given that, this code should work to set the new element as the next in the iteration:

ListIterator<T> i;
i.add(e);
i.previous(); // returns e
i.previous(); // returns element before e, and e will be next

这将起作用，除非列表开始迭代为空，在这种情况下将没有前一个元素.如果这是一个问题，您将不得不维护某种标志来指示这种极端情况.

This will work except when the list starts iteration empty, in which case there will be no previous element. If that's a problem, you'll have to maintain a flag of some sort to indicate this edge case.

这篇关于在迭代列表时将元素添加到列表中.(爪哇)的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持html5模板网！