how to fill a 2D panel in c# asp net webform

C# Corner

venus najad

2y725ASP.NET

hello every one

i will fill a 2D panel dynmically.

i have tried but i receive this error: Object reference not set to an instance of an object.

i have initialized the controls as following and try to fill the panel:

row=0, col=0;

HtmlForm form2 = new HtmlForm();
Panel[,] panelAd = new Panel[mm, 3];
Table mytable = new Table();

...

mytable.Controls.Add(trow_7);

if (col < 3)
{
panelAd[row, col].Controls.Add(mytable);
this.form2.Controls.Add(panelAd[row, col]);
}
else
{
row++;
col = 0;
panelAd[row, col].Controls.Add(mytable);
this.form2.Controls.Add(panelAd[row, col]);
}

how should i fix the error? on panelAd[row, col].Controls.Add(mytable); in if statement.

appreciate your respond with codes, kind regards

1 Reply

Know the answer? Post it — somebody with the same question will find it here.

Amit Mohanty2y ago

I think the error occurs because the Panel[,] panelAd array is created, but each individual Panel object inside that array is not initialized before you attempt to use it. Try the below code once:

int row = 0, col = 0;

HtmlForm form2 = new HtmlForm();
Panel[,] panelAd = new Panel[mm, 3];
Table mytable = new Table();

for (int i = 0; i < mm; i++)
{
    for (int j = 0; j < 3; j++)
    {
        panelAd[i, j] = new Panel(); // This initializes each panel
    }
}

mytable.Controls.Add(trow_7);

if (col < 3)
{
    panelAd[row, col].Controls.Add(mytable);
    this.form2.Controls.Add(panelAd[row, col]);
    col++;
}
else
{
    row++;
    col = 0;
    panelAd[row, col].Controls.Add(mytable);
    this.form2.Controls.Add(panelAd[row, col]);
}