C# How to add to list class?

Question

I am trying to add new obj to to list class but is telling me i need obj reference to the property. I cant understand exactly what i should do, can you give me a tip ?

public class CreateContact
{
  logic...
}

public class AddedContacts
{
    private List<CreateContact> Contact;

    public List<CreateContact> ClassCreateContact
    {
        get { return Contact; }
        set { this.Contact = value; }
    }
}

I want to create and add to the list the new created "CreateContact" by clicking a button.

private void button4_Click(object sender, EventArgs e)
    {

        CreateContact p = new CreateContact(textBox1.Text, textBox2.Text, textBox3.Text, textBox4.Text);
        AddedContacts.ClassCreateContact.add(p); // Error 1 An object reference is required for the non-static field, method, or property

    }

possible duplicate of [What is a NullReferenceException and how do I fix it?](http://stackoverflow.com/questions/4660142/what-is-a-nullreferenceexception-and-how-do-i-fix-it) — walther, Nov 04 '14 at 09:28
Nope, he's trying to access an instance property like a static one. — Dirk, Nov 04 '14 at 09:29
Both are irrelevant links. Question is about how to access instance member :) — Sriram Sakthivel, Nov 04 '14 at 09:29
You need to instantiate the Lists in your AddedContacts class's constructor! — TaW, Nov 04 '14 at 09:30
possible duplicate of [An object reference is required for the non-static field, method, or property](http://stackoverflow.com/questions/3775721/an-object-reference-is-required-for-the-non-static-field-method-or-property) — Default, Nov 04 '14 at 09:32

score 0 · Answer 1 · answered Nov 04 '14 at 09:29

You have defined a property in a class, but the property will only exist when an instance of the class exists. You need to create an instance via AddedContacts contacts = new AddedContacts(). Then contacts will be a reference to an actual object which contains a list.

If you want the class itself to contain a list, declare the property as static

score 0 · Accepted Answer · answered Nov 04 '14 at 09:34

0

You need to instantiate the Lists in your AddedContacts class's constructor:

public class AddedContacts
{
    private List<CreateContact> Contact;

    public List<CreateContact> ClassCreateContact
    {
        get { return Contact; }
        set { this.Contact = value; }
    }

    public AddedContacts()
    {
        Contact = new List<CreateContact>();
        ClassCreateContact = new List<CreateContact>();
    }

}

You also need to create an instance of AddedContacts to work with and finally you need to watch case: It is Add not add:

 AddedContacts AC = new AddedContacts();
 AC.ClassCreateContact.Add(p);

answered Nov 04 '14 at 09:34

TaW

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The problem is that he hasn't even got an instance of AddedContacts, so adding a field initialiser won't help – Matthew Sainsbury Nov 04 '14 at 09:35
You're faster than my copy of VS..! ;-) – TaW Nov 04 '14 at 09:37

serdar · Answer 3 · 2014-11-04T09:42:51.503

0

If you will not use the setter

public class AddedContacts
{
    public readonly List<CreateContact> Contact = new List<CreateContact>();
}

private void button4_Click(object sender, EventArgs e)
{
    CreateContact p = new CreateContact(textBox1.Text, textBox2.Text, textBox3.Text, textBox4.Text);
    AddedContacts ac= new AddedContacts();
    ac.Contact.Add(p);
}

edited Nov 04 '14 at 09:42

answered Nov 04 '14 at 09:34

serdar

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1

The problem is that he hasn't even got an instance of AddedContacts, so adding a field initialiser won't help – Matthew Sainsbury Nov 04 '14 at 09:36

C# How to add to list class?

3 Answers3