迭代列表时运行到java.util.ConcurrentModificationException
我正在尝试将记录列表拆分为记录子列表。我成功地将列表拆分为子列表,我想查看子列表的内容,但不知何故,我一直遇到ConcurrentModificationException 我的拆分方法:迭代列表时运行到java.util.ConcurrentModificationException,java,list,concurrentmodification,Java,List,Concurrentmodification,我正在尝试将记录列表拆分为记录子列表。我成功地将列表拆分为子列表,我想查看子列表的内容,但不知何故,我一直遇到ConcurrentModificationException 我的拆分方法: /** * @param list - list of results * @param size - how many sublists * @return ret - returns a list containing the sublists * */ p
/**
* @param list - list of results
* @param size - how many sublists
* @return ret - returns a list containing the sublists
* */
public static <T> List<List<T>> split(List<T> list, int size) throws NullPointerException, IllegalArgumentException {
if (list == null) {
throw new NullPointerException("The list parameter is null.");
}
if (size <= 0) {
throw new IllegalArgumentException("The size parameter must be more than 0.");
}
int recordsPerSubList = list.size() / size; // how many records per sublist
List<List<T>> sublists = new ArrayList<List<T>>(size); // init capacity of sublists
// add the records to each sublist
for (int i=0; i<size; i++) {
sublists.add(i, list.subList(i * recordsPerSubList, (i + 1) * recordsPerSubList));
}
// for the remainder records, just add them to the last sublist
int mod = list.size() % recordsPerSubList;
if (mod > 0) {
int remainderIndex = list.size() - mod;
sublists.get(size - 1).addAll(list.subList(remainderIndex, list.size()));
}
return sublists;
}
subList.get(size-1)
是列表子范围的实时视图,因此当您向其中添加元素时,您也将元素添加到原始列表中,同时尝试从list.subList
中取出元素。通常,在对列表进行迭代时,不能对其进行修改
最简单的解决方案不是将元素添加到子列表中。get(size-1)
,而只是更新它:
sublists.set(size - 1,
list.subList(remainderIndex - recordsPerSublist, list.size()));
发布异常堆栈跟踪。@Pangea补充道,当我试图对列表进行gson时,似乎出现了问题。此异常通常意味着列表在迭代时被修改。GSON在引擎盖下做什么?您可能还想将公司名称更改为其他名称。@ZiyaoWei公司名称?@ZiyaoWei哈哈,谢谢!目前在我的代码中,我有5个列表,其中前4个列表的长度相等。最后一个(第5个)列表将包含其他列表的长度加上任何剩余记录。该代码不会取代第五个列表吗?这看起来是答案,但是stacktrace说异常不会发生在
split
方法中;有什么评论吗?
java.util.ConcurrentModificationException
at java.util.SubList.checkForComodification(AbstractList.java:752)
at java.util.SubList.listIterator(AbstractList.java:682)
at java.util.AbstractList.listIterator(AbstractList.java:284)
at java.util.SubList.iterator(AbstractList.java:678)
at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.write(CollectionTypeAdapterFactory.java:95)
at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.write(CollectionTypeAdapterFactory.java:60)
at com.google.gson.Gson.toJson(Gson.java:546)
at com.google.gson.Gson.toJson(Gson.java:525)
at com.google.gson.Gson.toJson(Gson.java:480)
at com.google.gson.Gson.toJson(Gson.java:460)
at com.crover.QuoteSearchRover.execute(QuoteSearchRover.java:41)
at com.crover.CroverMain.execute(CroverMain.java:85)
at com.crover.CroverMain.main(CroverMain.java:35)
sublists.get(size - 1).addAll(list.subList(remainderIndex, list.size()));
sublists.set(size - 1,
list.subList(remainderIndex - recordsPerSublist, list.size()));