反序列化的 Xml 对象循环引发 NullReferenceException

问：

这是另一个问题的延续，所有与这个问题相关的代码都可以在这里找到。我遇到了一个奇怪的NullReferenceException错误，我只是无法弄清楚。我正在尝试从反序列化的 Web 响应构建一个表。当我去遍历对象项时，我遇到了 NRE。奇怪的是，我通过它自己测试了我的条件陈述，我能够抓住它。这是我的代码：

    public string getExample()
    {
        DataTable dt = new DataTable();
        XmlSerializer serializer = new XmlSerializer(typeof(WeeklyJobs));
        WeeklyJobs jobs;
        string xml = @"<?xml version = ""1.0""?>"
            + @"<WeeklyJobs>"
            + @"<DailyJobs Date = ""02/03/2012""/>"
            + @"<DailyJobs Date = ""02/04/2012"" TotalJobs = ""2"">"
            + @"<Jobs>"
            + @"<Job JobName = ""Job Name"" Description = ""Description""/>"
            + @"<Job JobName = ""Job Name"" Description = ""Description""/>"
            + @"</Jobs>"
            + @"</DailyJobs>"
            + @"<DailyJobs Date = ""02/05/2012"" TotalJobs = ""1"">"
            + @"<Jobs>"
            + @"<Job JobName = ""Job Name"" Description = ""Description""/>"
            + @"</Jobs>"
            + @"</DailyJobs>"
            + @"<DailyJobs Date = ""02/06/2012"" TotalJobs = ""2"">"
            + @"<Jobs>"
            + @"<Job JobName = ""Job Name"" Description = ""Description""/>"
            + @"<Job JobName = ""Job Name"" Description = ""Description""/>"
            + @"</Jobs>"
            + @"</DailyJobs>"
            + @"<DailyJobs Date = ""02/07/2012""/>"
            + @"</WeeklyJobs>";

        // Create an XmlTextReader
        using (XmlReader reader = XmlReader.Create(new StringReader(xml)))
        {
            jobs = (WeeklyJobs)serializer.Deserialize(reader);
        }

    // Create Table
        dt.Columns.Add("Date");
        dt.Columns.Add("JobName");
        dt.Columns.Add("Description");

        for (int i = 0; i < jobs.Items.Length; i++ )
        {
            DataRow dr;
            object[] rowItems = null;
            rowItems[0] = jobs.Items[i].Date;
            if(jobs.Items[i].Jobs == null || jobs.Items[i].Jobs.Length == 0) //NRE is thrown Here <--
            {
                rowItems[1] = "";
                rowItems[2] = "";
            }
            else
            {
                foreach (WeeklyJobsDailyJobsJobsJob job in jobs.Items[i].Jobs)
                {
                    rowItems[1] = job.JobName;
                    rowItems[2] = job.Description;
                }
            }

            dr = dt.NewRow();
            dr.ItemArray = rowItems;
            dt.Rows.Add(dr);
        }

        return dt.Rows.Count.ToString();
    }

现在这是我无法弄清楚的部分。当我注释掉 Create Table 代码并在我知道为 null 的项上添加 if 语句时，条件会正确处理它。这是我在注释掉 Create Table 代码后添加的内容：

        if(jobs.Items[0].Jobs == null)
        {
            return "null";
        }
        else
        {
            return jobs.Items[0].Jobs.Length.ToString();
        }

它返回“null”。我不确定发生了什么。也许我的 for 循环设置不正确？感谢您的帮助！