反序列化Xml对象循环抛出NullReferenceException
本文关键字:NullReferenceException 循环 Xml 对象 反序列化 | 更新日期: 2023-09-27 18:07:33
这是另一个问题的延续,与这个问题相关的所有代码都可以在这里找到。我正在经历一个奇怪的NullReferenceException错误,我只是无法弄清楚。我正试图从反序列化的web响应建立一个表。当我去迭代对象项时,我碰到了一个NRE。奇怪的是,我自己测试了条件语句,我能够捕捉到它。下面是我的代码:
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();
}
这是我不明白的部分。当我注释掉Create Table代码并在我知道为空的项上添加if语句时,条件会正确地处理它。下面是我注释掉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();
}
返回"null"。我不知道发生了什么事。也许我的for循环没有正确设置?谢谢你的帮助!
你知道,我经常看到调试器在之后的行中把执行点作为异常,
也许这是你的问题:
object[] rowItems = null;
rowItems[0] = jobs.Items[i].Date;
NRE是由索引器调用null数组抛出的。