mscorlib.dll中发生类型为'System.ArgumentOutOfRangeException'的未处理异常

Question

在以下代码中，出现以下错误。

mscorlib.dll中发生类型为'System.ArgumentOutOfRangeException'的未处理异常

附加信息：索引超出范围。 必须为非负数并且小于集合的大小。

这是代码：

public ProcessInformation GetMaxRunTimeForApplicationsBetween(DateTime StartingTime, DateTime EndingTime)
    {

        //Filter Based on Timer
        List<ProcessInformation> filterList = new List<ProcessInformation>();

        foreach (HarvestApp.ProcessInformation item in this.ProcessList)
        {
            if (item.started_at.CompareTo(StartingTime) >= 0 && item.ended_at.CompareTo(EndingTime) <= 0)
            {
                filterList.Add(item);
            }
        }

        //Count Max Occurrence of Application
        List<int> countApplicationList = new List<int>();
        List<string> applicationNameList = new List<string>();


        foreach (HarvestApp.ProcessInformation item in filterList)
        {
            if (applicationNameList.Contains(item.name))
            {
                countApplicationList[applicationNameList.IndexOf(item.name)]++;
            }
            else
            {
                applicationNameList.Add(item.name);
                countApplicationList.Add(1);

            }
        }


        //if (countApplicationList.Count == 0)
        //{
        //    throw new InvalidOperationException("Empty list");
        //}


        int max = int.MinValue;
        foreach (int item in countApplicationList)
        {
            if (item > max)
            {
                max = item;
            }

        }

            //Return corresponding ProcessInformation Class of applicationNameList
            return filterList[filterList.FindIndex(delegate
                (ProcessInformation proc)
                {
                    return proc.name.Equals(applicationNameList[countApplicationList.IndexOf(max)], StringComparison.Ordinal);
                })];




    }

Answer 1

我认为错误行在这里：

return filterList[filterList.FindIndex(delegate(ProcessInformation proc)
    {
        return proc.name.Equals(applicationNameList[countApplicationList.IndexOf(max)], StringComparison.Ordinal);
    })];

因为List<T>.FindIndex在找不到索引时可以返回-1 。

相反，您应该在使用索引之前测试索引是否小于0，这表明存在错误：

int result = filterList.FindIndex(delegate(ProcessInformation proc)
        {
            return proc.name.Equals(applicationNameList[countApplicationList.IndexOf(max)], StringComparison.Ordinal);
        });

if(result < 0) throw new Exception("Cant't Find ProcessInformation"); 
return  filterList[result];

Answer 2

这是问题所在：

if (applicationNameList.Contains(item.name))
{
       **countApplicationList[applicationNameList.IndexOf(item.name)]++;**
}

应该是这样

if (applicationNameList.Contains(item.name) && countApplicationList.Count > applicationNameList.IndexOf(item.name))
    {
       countApplicationList[applicationNameList.IndexOf(item.name)]++;
    }