how can i make this code more optimized

how can i optimized this code? i dont like to have case statement, is there a way i can improve this code?

protected void ddlFilterResultBy_SelectedIndexChanged(object sender, EventArgs e)
{ 
    string selVal = ddlFilterResultBy.SelectedValue.ToString().ToLower();

    switch (selVal)
    {
        case "date":
            pnlDate.Visible = true; 
            pnlSubject.Visible = false;
            pnlofficer.Visible = false;
            pnlCIA.Visible = false;
            pnlMedia.Visible = false;
            pnlStatus.Visible = false;                    
            break;

        case "subject":
            pnlDate.Visible = false;
            pnlSubject.Visible = true;
            pnlofficer.Visible = false;
            pnlCIA.开发者_如何学运维Visible = false;
            pnlMedia.Visible = false;
            pnlStatus.Visible = false;
            break;

        case "officer":
            pnlDate.Visible = false;
            pnlSubject.Visible = false;
            pnlofficer.Visible = true;
            pnlCIA.Visible = false;
            pnlMedia.Visible = false;
            pnlStatus.Visible = false;
            break;

        case "status":
            pnlDate.Visible = false;
            pnlSubject.Visible = false;
            pnlofficer.Visible = false;
            pnlCIA.Visible = false;
            pnlMedia.Visible = false;
            pnlStatus.Visible = true;
            break;

        default:
            pnlDate.Visible = false;
            pnlSubject.Visible = false;
            pnlofficer.Visible = false;
            pnlCIA.Visible = false;
            pnlMedia.Visible = false;
            pnlStatus.Visible = false;
            break;
    }
}

Easy enough. You're only ever making one item visible depending on the case option, so just set the visibility as follows:

pnlDate.Visible = (selVal == "date"); 
pnlSubject.Visible = (selVal == "subject");
pnlofficer.Visible = (selVal == "officer");
pnlCIA.Visible = false;
pnlMedia.Visible = false;
pnlStatus.Visible = (selVal == "status");    

This is better than setting everything to visible = false; and then only showing the item you need as this contains it all into just 6 lines of code for the actual visibility setting.

Another way:

// set everything to false   
Dictionary<string, type> d = new Dictionary<string, type>()
{
    {"date", pnlDate},
    {"subject", plnSubject},
    {"officer", plnOfficer},
    {"status", plnStatus}
};

d[selVal].Visible = true;

protected void ddlFilterResultBy_SelectedIndexChanged(object sender, EventArgs e)
            { 
                string selVal = ddlFilterResultBy.SelectedValue.ToString().ToLower();
                        pnlDate.Visible = false;
                        pnlSubject.Visible = false;
                        pnlofficer.Visible = false;
                        pnlCIA.Visible = false;
                        pnlMedia.Visible = false;
                        pnlStatus.Visible = false;
                switch (selVal)
                {
                    case "date":
                        pnlDate.Visible = true;                    
                        break;

                    case "subject":
                        pnlSubject.Visible = true;
                        break;

                    case "officer":
                        pnlofficer.Visible = true;
                        break; 
                    case "status":
                        pnlStatus.Visible = true;
                        break;  
                }

            }

You could do this:

protected void ddlFilterResultBy_SelectedIndexChanged(object sender, EventArgs e) { 
  string selVal = ddlFilterResultBy.SelectedValue.ToString().ToLower();

  pnlDate.Visible = (selVal == "date");
  pnlSubject.Visible = (selVal == "subject");
  pnlofficer.Visible = (selVal == "officer");
  pnlCIA.Visible = (selVal == "cia");
  pnlMedia.Visible = (selVal == "media");
  pnlStatus.Visible = (selVal == "status");
}

Or this one, while less readable, would be more accurate:

protected void ddlFilterResultBy_SelectedIndexChanged(object sender, EventArgs e) { 
  string selVal = ddlFilterResultBy.SelectedValue.ToString();

  pnlDate.Visible = String.Equals(selVal, "date", StringComparison.OrdinalIgnoreCase);
  pnlSubject.Visible = String.Equals(selVal, "subject", StringComparison.OrdinalIgnoreCase);
  pnlofficer.Visible = String.Equals(selVal, "officer", StringComparison.OrdinalIgnoreCase);
  pnlCIA.Visible = String.Equals(selVal, "cia", StringComparison.OrdinalIgnoreCase);
  pnlMedia.Visible = String.Equals(selVal, "media", StringComparison.OrdinalIgnoreCase);
  pnlStatus.Visible = String.Equals(selVal, "status", StringComparison.OrdinalIgnoreCase);
}

There is a difference between optimization and improving readability. So I guess you are looking at improving readability more as optimization is not really needed here. There is no algo here which you can tune to make this faster by a significant time .

Answer 1 and 2 will be my choice of improving readability

I think you need a tabcontrol here..

Just hide the tabs if you don't like those, and page index via code.

The advantage is that you'll be able to edit and view the GUI at designtime.

It'll be a lot easier to maintain.