How to solve Object reference not set to an instance of an object.? [duplicate]

Question

In my asp.net program.I set one protected list.And i add a value in list.But it shows Object reference not set to an instance of an object error

protected List<string> list;
protected void Page_Load(object sender, EventArgs e)
{
     list.Add("hai");
}

How to solve this error?

Almost all cases of NullReferenceException are the same. Please see "What is a NullReferenceException in .NET?" for some hints. — John Saunders
– John Saunders, Commented Nov 22, 2013 at 8:28

Tinsa · Accepted Answer · 2013-11-22 08:15:58Z

102

You need to initialize the list first:

protected List<string> list = new List<string>();

answered Nov 22, 2013 at 8:15

Tinsa

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Comments

Soner Gönül · Accepted Answer · 2013-11-22 08:22:50Z

32

I think you just need;

List<string> list = new List<string>();
list.Add("hai");

There is a difference between

List<string> list;

and

List<string> list = new List<string>();

When you didn't use new keyword in this case, your list didn't initialized. And when you try to add it hai, obviously you get an error.

answered Nov 22, 2013 at 8:16

Soner Gönül

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