Question

如何在迭代时修改arraylist？我希望只有在我迭代的情况下处理它的答案，请不要回答我可以保存它然后修改它。

for (ListIterator<CardGroup> ShortSeqGroupListIterator = ShortSeqGroupList
                            .listIterator(); ShortSeqGroupListIterator.hasNext();) {
    CardGroup ShortSeqGroup = ShortSeqGroupListIterator.next();
    System.out.println("Iteration ---  "+ShortSeqGroup.getCardList());
    for (ListIterator<CardGroup> cardGroupListIterator = this.cardGroupList
                                .listIterator(); cardGroupListIterator.hasNext();) {
        CardGroup cardGroup = cardGroupListIterator.next();
        if (cardGroup.getCardGroupType() == CardGroupType.PURESEQUENCE
            || cardGroup.getCardGroupType() == CardGroupType.SHORTSEQUENCE) {
            continue;
        }
        Listindex = cardGroupListIterator.nextIndex() - 1;
        listOfIndex.add(Listindex); 
        cardGroup.setCardGroupType(CardGroupType.NONE);
        this.mergeExtraGroups();
    } 
    ShortSeqGroup.setCardGroupType(CardGroupType.NONE);
    this.mergeExtraGroups();
    this.markSets();
    this.markSequences(false);
    int PenaltyPointsShSeq = totalPenaltyOfUser(this.cardGroupList);
    PenaltyMapShortSeq.put(PenaltyPointsShSeq, this.cardGroupList);
    this.cardGroupList = clonedCardGroupList;
    System.out.println("&************************&");
    this.print();
}
NavigableMap<Integer, List<CardGroup>> descendedPenaltyMapShortSeq=PenaltyMapShortSeq.descendingMap();
System.out.println(descendedPenaltyMapShortSeq.firstKey());

我想在列表上操作，然后在保存操作后，我需要返回列表的先前状态.. 问题当然是并发修改异常。

this.cardList是我正在操作的那个，克隆的cardgrouplist是它的副本...... cardGrouplist第一个元素再次包含：一个arraylist

Answer 1

请勿使用Iterator，将其切换为正常的for(int i = 0; i < list.length; i++)循环。

Answer 2

在迭代时修改集合看起来很麻烦。我建议你迭代收集要添加/删除的项目列表。然后，相应地执行添加/删除收集的项目。

在迭代时修改数组列表

2 个答案: