問題描述

情況:我有一個自定義對象的 TreeSet，并且我還使用了一個自定義比較器.我創(chuàng)建了一個迭代器以在此 TreeSet 上使用.

SITUATION: I have a TreeSet of custom Objects and I have also used a custom Comparator. I have created an iterator to use on this TreeSet.

TreeSet<Custom> ts=new TreeSet<Custom>();
Iterator<Custom> itr=ts.iterator();
while(itr.hasNext()){
    Custom c=itr.next();
    //Code to add a new element to the TreeSet ts
}

問題:好吧，我想知道，如果我在 while 循環(huán)中向 TreeSet 添加一個新元素，那么該新元素是否會立即排序.換句話說，如果我在 while 循環(huán)中添加一個新元素并且它小于我當(dāng)前在 c 中保存的元素，那么在下一次迭代中，我會在 c 中獲得與上一次迭代中相同的元素嗎?(因為經(jīng)過排序后，新添加的元素會占據(jù)當(dāng)前元素之前的某個位置).

QUESTION: Well I want to know that if I add a new element to the TreeSet within the while loop, then will that new element get sorted immediately. In other words, if I add a new element within the while loop and it is less than the one which I am currently holding in c, then in the next iteration will I be getting the same element in c as in the last iteration?(since after sorting, the newly added element will occupy a place somewhere before the current element).

推薦答案

如果您在迭代期間添加一個元素，您的下一次迭代器調(diào)用可能會拋出 ConcurrentModificationException.請參閱 TreeSet 文檔中的快速失敗行為.

If you add an element during your iteration, your next iterator call will likely throw a ConcurrentModificationException. See the fail-fast behavior in TreeSet docs.

要迭代和添加元素，您可以先復(fù)制到另一個集合:

To iterate and add elements, you could copy first to another set:

TreeSet<Custom> ts = ...
TreeSet<Custom> tsWithExtra = new TreeSet(ts);

for (Custom c : ts) {
  // possibly add to tsWithExtra
}

// continue, using tsWithExtra

或者按照 Colin 的建議創(chuàng)建一個單獨的集合，以便在迭代后與 ts 合并.

or create a separate collection to be merged with ts after iteration, as Colin suggests.

這篇關(guān)于在 TreeSet 上使用迭代器的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網(wǎng)！