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- What is a NullReferenceException, and how do I fix it? 31 answers
什么是NullReferenceException,我该如何解决? 31个答案
I am getting the object reference error in just start of the method.
我刚刚在方法的开头得到了对象引用错误。
For Ex.:
259: public ActionResult ShowAddress(FormCollection formCollection)
260: {
In the above sample i am getting the error Line number 260.
在上面的示例中,我得到错误行号260。
2 个解决方案
#1
Here is the code from the question comments
这是问题评论中的代码
259: public ActionResult ShowAddress(FormCollection formCollection) {
260: long _userId= long.Parse(formCollection["UserId"].ToString());
261: UserDetails _userDetails = _userDAL.GetUserDetails(_userId);
262: if(!string.IsNullOrEmpty(_userDetails.Address1)) return RedirectToAction("GetAddress", "User"); else return View(); }
If you're seeing a NullReferenceException at line 260, either formCollection or the result of formCollection["UserId"] is null. You need to account for this in your code. For instance you could do the following.
如果您在第260行看到NullReferenceException,则formCollection或formCollection [“UserId”]的结果为null。您需要在代码中考虑到这一点。例如,您可以执行以下操作。
public ActionResult ShowAddress(FormCollection formCollection) {
if ( null == formCollection ) {
return View();
}
object obj = formCollection["UserId"];
if ( null == obj ) {
return View();
}
long _userId = long.Parse(obj.ToString());
...
}
#2
Finally, Enough information to attempt to post an answer...
最后,有足够的信息试图发布答案......
I suppose formCollection must be null.
我想formCollection必须为null。
PS: You'd benifit from reading this: http://catb.org/esr/faqs/smart-questions.html#intro Think of it as a life investment in life assurance.
PS:你读这篇文章是有益的:http://catb.org/esr/faqs/smart-questions.html#intro把它当作生命保障的生命投资。
#1
Here is the code from the question comments
这是问题评论中的代码
259: public ActionResult ShowAddress(FormCollection formCollection) {
260: long _userId= long.Parse(formCollection["UserId"].ToString());
261: UserDetails _userDetails = _userDAL.GetUserDetails(_userId);
262: if(!string.IsNullOrEmpty(_userDetails.Address1)) return RedirectToAction("GetAddress", "User"); else return View(); }
If you're seeing a NullReferenceException at line 260, either formCollection or the result of formCollection["UserId"] is null. You need to account for this in your code. For instance you could do the following.
如果您在第260行看到NullReferenceException,则formCollection或formCollection [“UserId”]的结果为null。您需要在代码中考虑到这一点。例如,您可以执行以下操作。
public ActionResult ShowAddress(FormCollection formCollection) {
if ( null == formCollection ) {
return View();
}
object obj = formCollection["UserId"];
if ( null == obj ) {
return View();
}
long _userId = long.Parse(obj.ToString());
...
}
#2
Finally, Enough information to attempt to post an answer...
最后,有足够的信息试图发布答案......
I suppose formCollection must be null.
我想formCollection必须为null。
PS: You'd benifit from reading this: http://catb.org/esr/faqs/smart-questions.html#intro Think of it as a life investment in life assurance.
PS:你读这篇文章是有益的:http://catb.org/esr/faqs/smart-questions.html#intro把它当作生命保障的生命投资。