Java 安卓 : Comparator gets OutOfBoundsException

Question

我不是专家，不知道为什么会越界

public class ParticipantIndexComparator implements Comparator<Integer> {
    final List<Participant> participants;       
    public ParticipantIndexComparator(ArrayList<Integer> numbersToSort) {
        Log.d("MyLog","numbersToSort.size=" + numbersToSort.size());

        participants = new ArrayList<Participant>();

        for (int i=0;i<numbersToSort.size();i++) {     
            participants.add(i, competition.participant.get(numbersToSort.get(i)));
            participants.get(i).comparator = numbersToSort.get(i);
        }

        Log.d("MyLog","participants.size="+participants.size());
    }

    @Override
    public int compare(Integer i1, Integer i2) {
        Log.d("MyLog","in compare: participants.size=" + participants.size() + "i1=" + i1 + " i2=" + i2);
        long l1 = participants.get(i1).kpTime.get(kpSelected); 
        long l2 = participants.get(i2).kpTime.get(kpSelected);
        return Long.valueOf(l1).compareTo(Long.valueOf(l2));
    }
}

好吧，我的第一个日志显示了 participants.size=8.第二个日志显示 participants.size=8.第三个日志显示 participants.size=8, i1=13 i2=14.

为什么？？？为什么我在每一步检查尺寸时都是 13 和 14 而它总是 8 - 我无法理解。我不是专家，我自己也想不通

这里是堆栈跟踪:

11-24 02:41:23.612: E/AndroidRuntime(4802): java.lang.IndexOutOfBoundsException: Invalid index 14, size is 8
11-24 02:41:23.612: E/AndroidRuntime(4802):     at java.util.ArrayList.throwIndexOutOfBoundsException(ArrayList.java:251)
11-24 02:41:23.612: E/AndroidRuntime(4802):     at java.util.ArrayList.get(ArrayList.java:304)
11-24 02:41:23.612: E/AndroidRuntime(4802):     at ru.maximhasanov.skitimer.FinalProtocolActivity$ParticipantIndexComparator.compare(FinalProtocolActivity.java:311)
11-24 02:41:23.612: E/AndroidRuntime(4802):     at ru.maximhasanov.skitimer.FinalProtocolActivity$ParticipantIndexComparator.compare(FinalProtocolActivity.java:1)
11-24 02:41:23.612: E/AndroidRuntime(4802):     at java.util.TimSort.countRunAndMakeAscending(TimSort.java:320)
11-24 02:41:23.612: E/AndroidRuntime(4802):     at java.util.TimSort.sort(TimSort.java:185)
11-24 02:41:23.612: E/AndroidRuntime(4802):     at java.util.TimSort.sort(TimSort.java:169)
11-24 02:41:23.612: E/AndroidRuntime(4802):     at java.util.Arrays.sort(Arrays.java:2038)
11-24 02:41:23.612: E/AndroidRuntime(4802):     at java.util.Collections.sort(Collections.java:1891)
11-24 02:41:23.612: E/AndroidRuntime(4802):     at ru.maximhasanov.skitimer.FinalProtocolActivity.sortNumbers(FinalProtocolActivity.java:213)

Answer 1

好的，我要试一试。我想我有点了解你的情况。

正如我在评论中所说，我认为 numbersToSort持有 competition.participant 子集的数字列表(本质上是索引)您想要按特定 kpTime 排序.

如果这是正确的，那么你得到 OutOfBoundsException 的原因是因为你的numbersToSort包含大于 participants 大小的数字(索引) , 作为 participants是更大列表的子集。

我相信你应该做的是创建你的 ArrayList<Participant> participants在 sortNumbers FinalProtocolActivity的方法| , 然后调用 Collections.sort()在上面加上以下 Comparator :

public class ParticipantIndexComparator implements Comparator<Participant>
{
    public int compare(Participant p1, Participant p2)
    {
        Long time1 = p1.kpTime.get(kpSelected);
        Long time2 = p2.kpTime.get(kpSelected);
        return Long.valueOf(time1).compareTo(time2);
    }
}