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why do I get nullref....?

Posted on 2009-07-09
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Last Modified: 2012-05-07
Why do I get nullreference here?

 CM.Contacts.Add(cust);

How should it be done?
namespace MyPhoneBook
{
    public partial class Form1 : Form
    {
        private ContactManager CM;
 
 
        public Form1()
        {
            InitializeComponent();
            ContactManager CM = new ContactManager();
        }
 
        private void button1_Click(object sender, EventArgs e)
        {
            Contact cust = new Contact();
            cust.FirstName = textBox1.Text;
            CM.Contacts.Add(cust);
            
 
 
            Console.ReadLine();
        }
    }
}
 
 
 
 
--------------------------
 
using System;
using System.Collections.Generic;
using System.Text;
 
namespace Persons
{
    public class ContactManager
    {
 
        //Deklaration
        List<Contact> contact;
        bool exists = false;
 
        #region Konstruktor
 
 
 
        public ContactManager()
        {
            contact = new List<Contact>();           
            exists = true;
        } //end CustomerManager
 
 
 
         public ContactManager(List<Contact> constact)
        {
            this.contact = constact;
        } //end CustomerManager
 
        #endregion
        
 
        #region Egenskaper
 
 
 
        public int Count
        {
            get { return contact.Count; }
        } //end Count
 
 
 
        public List<Contact> Contacts
        {
            get { return contact; }
            set { contact = value; }
        } //end Customers
 
 
        #endregion
 
 
        #region Metoder
 
 
 
        public int Search(Contact cust)
        {
            int found = -1;
 
            if (exists)
            {
                for (int i = 0; i < contact.Count; i++)
                {
                    if (contact[i].FirstName.Equals(cust.FirstName) && contact[i].LastName.Equals(cust.LastName))
                    {
                        found = i;
                    } //end if                                    
                } //end for
            } //end if
 
            return found;
        } //end Search
 
 
 
        public void DeleteCustomer (int index) 
        {
            if (exists)
            {
                contact.RemoveAt(index);                
            } //end if        
        } //end DeleteCustomer
 
 
 
        public void ChangeCustomer(Contact cust)
        {
 
        }
 
 
 
        public Contact GetCustomer(int index)
        {
            return null;
        } //end GetCustomer
 
 
 
 
        public void AddCustomer(Contact cust)
        {
            if(exists)
            {
                contact.Add(cust);
            } //end if
 
            else
            {
                contact = new List<Contact>();
                contact.Add(cust);
                exists = true;
            } //end else            
        } //end AddCustomer
 
 
 
 
 
        #endregion
 
    } //end class
} //end namespace

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Question by:Mickeys
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2 Comments
 
LVL 5

Accepted Solution

by:
Pablissimo earned 500 total points
ID: 24811833
       public Form1()
        {
            InitializeComponent();
            ContactManager CM = new ContactManager();
        }


is wrong - should be

        public Form1()
        {
            InitializeComponent();
            CM = new ContactManager();
        }

You're actually declaring a local variable called CM (rather than initialising the CM member variable) at the minute.
0
 

Author Closing Comment

by:Mickeys
ID: 31601489
Ah thx. Get blind sometimes :-)  .....or maybe all the time is a more correct word. :-)
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