对象引用未设置为对象的实例，但是？

I must be missing something here, but I've got an instance of my submission object called up, in scope, and when I try to use it in another line, I throw this error about not setting the reference to an instance. What gives?

我必须在这里遗漏一些东西,但是我已经在范围内调用了我的提交对象的实例,当我尝试在另一行中使用它时,我抛出了关于不设置对实例的引用的错误。是什么赋予了?

protected void Page_Load(object sender, EventArgs e)
{

    string x = Request.QueryString["SubmissionId"];

    SubmissionService ss = new SubmissionService();
    Submission sub = ss.getSubmissionByID(x);

if (sub.Status1.Equals(0))
    {
        PanelComment.Visible = false;

    }
    else

4 个解决方案

#1

It's possible that the Status1 property on your submission object 'sub' is null...

提交对象'sub'上的Status1属性可能为null ...

#2

These could be null:

这些可以为null:

ss 
sub
sub.Status1
x

Put a breakpoint, and debug...

放一个断点,然后调试......

#3

Given the code that you supplied, there can be three causes:

鉴于您提供的代码,可能有三个原因:

the "Status1" property is null, this would generate a NullReferenceException.

“Status1”属性为null,这将生成NullReferenceException。

PanelComment is null

PanelComment为null

sub is null

sub为null

#4

Given the code, the following properties could be null:

给定代码,以下属性可以为null:

Submission sub (If there is no submission with the ID = x)

提交子(如果没有提交ID = x)

sub.Status1
List item

PanelComment

Just change your code by the following:

只需通过以下方式更改您的代码:

Submission sub = String.IsNullOrEmpty(x) ? null : ss.getSubmissionByID(x);

if (sub!= null && sub.Status1 == 0){
...

It should fix most of the null references.

它应该修复大多数空引用。

#1