Object reference not set to an instance of an object.

Question

4.00/5 (1 vote)

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I created a UserControl:

The cod in the UserControl form is:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Data;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using GestiuneProduse;

namespace FereastraPrincipala.Contracte
{
    public partial class InformatiiContracte : UserControl
    {

        private bool ClientiAdaugati = false;

        public InformatiiContracte()
        {
            InitializeComponent();
            
        }

       

        private void InformatiiContracte_Load(object sender, EventArgs e)
        {
            txtNumeClient.Focus();
            InformatiiDespreClient();
        }

        void InformatiiDespreClient()
        {

            txtNumeClient.Items.Clear();
            Program.Connection.CommandText = "select RTRIM(Nume) + ', '+ RTRIM(Prenume) AS NumeComplet, ClientId from DateClientiAmanet ORDER BY Nume";
            DataTable Table = new DataTable();
            Program.Connection.FillDataTable(Table, true);

            txtNumeClient.DataSource = Table;
            txtNumeClient.DisplayMember = "NumeComplet";
            txtNumeClient.ValueMember = "ClientId";
            ClientiAdaugati = true;

        }


        void InformatiiDespreClientDetaliate()
        {

            Program.Connection.CommandText = "select * from DateClientiAmanet where ClientId=" + txtNumeClient.SelectedValue.ToString();
            DataTable Table = new DataTable();
            Program.Connection.FillDataTable(Table, true);
            foreach (DataRow Row in Table.Rows)
            {
                txtNume.Text = Table.Rows[0]["Nume"].ToString() + ", " + Table.Rows[0]["Prenume"].ToString();
                txtAdresa.Text = "Strada " + Table.Rows[0]["Strada"].ToString() + ", nr. " + Table.Rows[0]["Numarul"].ToString() + ", bl. " + Table.Rows[0]["Bloc"].ToString() + ", sc. " + Table.Rows[0]["Scara"].ToString() + ", et. " + Table.Rows[0]["Etajul"].ToString() + ", ap. " + Table.Rows[0]["Apartament"].ToString();
                txtCNP.Text = Table.Rows[0]["CNP"].ToString();

            }

            this.txtBoxDetaliiClient.Text = "Client: " + txtNumeClient.SelectedValue.ToString();
        }

        private void txtNumeClient_SelectedIndexChanged(object sender, EventArgs e)
        {
            if (this.ClientiAdaugati)
                InformatiiDespreClientDetaliate();

        }

        
    }
}

In the main form I drag the UserControl to the form,
when i run the program i have an error:

Object reference not set to an instance of an object.

the cod in the main form is:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using Microsoft.Win32;
using FereastraPrincipala.Contracte;

namespace FereastraPrincipala
{
    public partial class frmPrincipala : Form
    {
        
        public frmPrincipala()
        {
            InitializeComponent();
            SeteazaCuloare("Azure");

            informatiiContracte1.Visible = false;
            
         
        }

       

        public void SeteazaCuloare(string Name)
        {
            Color HaloColor = Color.White;
            switch (Name)
            {
                case "Dark":
                    this.BackColor = Color.FromArgb(88,77,69);
                    HaloColor = Color.FromArgb(200,200,200);
                    SetBase(87,61,53,HaloColor);
                    break;
                case "Nature":
                    this.BackColor = Color.FromArgb(78, 127, 52);
                    HaloColor = Color.FromArgb(254, 209, 94);
                    SetBase(73, 118, 46,HaloColor );
                    break;
                case "Dawn":
                    this.BackColor = Color.FromArgb(177, 108, 45);
                    SetBase(172, 99, 39, Color.FromArgb(254, 209, 94));
                    break;
                case "Corn":
                    this.BackColor = Color.FromArgb(230, 193, 106);
                    SetBase(225, 184, 100, Color.FromArgb(191, 219, 255));
                    break;
                case "Chocolate":
                    this.BackColor = Color.FromArgb(87, 54, 34);
                    SetBase(82, 45, 28, Color.FromArgb(232,80,90));
                    break;
                case "Navy":
                    this.BackColor = Color.FromArgb(88,121,169);
                    SetBase(84,112,163, Color.FromArgb(254, 209, 94));
                    break;
                case "Ice":
                    this.BackColor = Color.FromArgb(235, 243, 236);
                    SetBase(228, 234, 230, Color.FromArgb(254, 209, 94));
                    break;
                case "Vanilla":
                    this.BackColor = Color.FromArgb(233, 243, 213);
                    SetBase(228, 234, 207, Color.FromArgb(254, 209, 94));
                    break;
                case "Canela":
                    this.BackColor = Color.FromArgb(235, 226, 197);
                    SetBase(228, 217, 191, Color.FromArgb(254, 209, 94));
                    break;
                case "Cake":
                    this.BackColor = Color.FromArgb(235, 213, 197);
                    SetBase(228, 204, 198, Color.FromArgb(254, 209, 94));
                    break;
                default:
                    
                    this.BackColor = Color.FromArgb(191, 219, 255);
                    SetBase(215, 227, 242, Color.FromArgb(254, 209, 94));
                    break;
            }


        }

        

        private void ribbonButton5_Click(object sender, EventArgs e)
        {

            informatiiContracte1.Visible = true;

        }

             
        
    }


    
}

so how do I remove error?

Posted 13-Mar-11 5:02am

aciobanita

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Comments

OriginalGriff 13-Mar-11 11:08am

What line is the exception occurring on?

aciobanita 13-Mar-11 11:17am

at FereastraPrincipala.Contracte.InformatiiContracte.InformatiiDespreClient() in E:\AddressBook AMANET\TRIAL MAKER\Source\TabStripApp\Contracte\InformatiiContracte.cs:line 36
at FereastraPrincipala.Contracte.InformatiiContracte..ctor() in E:\AddressBook AMANET\TRIAL MAKER\Source\TabStripApp\Contracte\InformatiiContracte.cs:line 21

aciobanita 13-Mar-11 11:20am

And when i drag the UserControl to the form

a nother error

The variable 'informatiiContracte1' is either undeclared or was never assigned. E:\AddressBook AMANET\TRIAL MAKER\Source\TabStripApp\FereastraPrincipala.Designer.cs

at line:
this.Controls.Add(this.informatiiContracte1);

aciobanita 13-Mar-11 11:21am

Im new in c#,

1 solution

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OriginalGriff · Answer 1 · 2011-03-13T05:39:00

Solution 1

Line 36 references "Program" and it's Property "Connection" and then "CommandText" which I do not see the definition of anywhere: Is the class class continued in a different file?

It looks like you have lifted a file directly from a Demo of some kind, and not included all the files you need.

"If i remouve the InformatiiDespreClient(); from
private void InformatiiContracte_Load(object sender, EventArgs e)
{
txtNumeClient.Focus();
InformatiiDespreClient();
}
the errors errors disappear"

Yes, because you are no longer referencing the variable that is not initialized.

Start by putting a breakpoint on the first line in "InformatiiDespreClient" and check each reference in turn. Then look for the code that initialises it.

Sorry, but without knowing your code, I can only be vague... :)

Posted 13-Mar-11 5:39am

OriginalGriff

Updated 13-Mar-11 6:13am

v2

Comments

aciobanita 13-Mar-11 12:07pm

ies the conections is in a separate file. The program run, but i whant to remove the error?

aciobanita 13-Mar-11 12:09pm

If i remouve the InformatiiDespreClient(); from

private void InformatiiContracte_Load(object sender, EventArgs e)
{
txtNumeClient.Focus();
InformatiiDespreClient();
}

the errors errors disappear

aciobanita 13-Mar-11 12:10pm

I have to declare an instance for my UserContro in the main form?

OriginalGriff 13-Mar-11 12:34pm

Answer updated

aciobanita 13-Mar-11 12:44pm

Is sims that a eror apeer at line 999 in FereastraPrincipala.Designer.cs

this.Controls.Add(this.informatiiContracte1);

OriginalGriff 14-Mar-11 4:44am

Yes, it will: because the Controls.Add method will cause your Load event to happen. You need to know where in "InformatiiDespreClient" the problems occurs. If you can't breakpoint it and single step, you will have to add tracing statements to write info to the console - it will appear in the "output" pane of the panel where your compilation errors are shown.

Sergey Alexandrovich Kryukov 13-Mar-11 15:30pm

Griff, how you get patience for reading of all that? My 5.
--SA