Windows Form ListBox Selections

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I am trying to develop a Digital Clock in a Windows Form that allows the user to choose the TimeZone they want to display from a ListBox. How can I convert the SelectedItem in the event handler to the corresponding TimeZone? Thx.

MIDL

lb1.Items.Add("(UTC-12:00) International Date Line West");
           lb1.Items.Add("(UTC-11:00) Coordinated Universal Time-11");
           lb1.Items.Add("(UTC-11:00) Samoa");
           lb1.Items.Add("(UTC-10:00) Hawaii");

        public void timer1_Tick(object sender, EventArgs e)
        {
            DateTime timeUtc = DateTime.UtcNow;
            TimeZoneInfo HstZone = TimeZoneInfo.FindSystemTimeZoneById("Hawaiian Standard Time");
            TimeZoneInfo CstZone = TimeZoneInfo.FindSystemTimeZoneById("China Standard Time");
            DateTime HstTime = TimeZoneInfo.ConvertTimeFromUtc(timeUtc, HstZone);
            DateTime CstTime = TimeZoneInfo.ConvertTimeFromUtc(timeUtc, CstZone);

            if (sender == timer1)
            {
                LocalDisplay.Text = DateTime.Now.ToString();
                Clock2.Text = DateTime.UtcNow.ToString();
                Clock4.Text = HstTime.ToString();
                Clock3.Text = CstTime.ToString();
                
            }
        }

Posted 15-Jul-11 11:20am

77Jeff

Updated 15-Jul-11 11:41am

Dr.Walt Fair, PE

v2

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Dr.Walt Fair, PE 15-Jul-11 17:42pm

Fixed the code formatting due to a misplaced </pre> tag.

4 solutions

Solution 1

you can add a TimeZoneInfo objects into the listBox

then get the seleteditem object ( TimeZoneInfo object ) from the listbox.

 TimeZoneInfo HstZone ; 
....
lb1.Items.Add(HstZone.ToString() );


...
public void timer1_Tick(object sender, EventArgs e)
       {
     TimeZoneInfo selectedtimeZone  = (TimeZoneInfo)lb1.SelectedItem ; 

}

good luck.

Posted 15-Jul-11 12:04pm

Salmen Essridi

Updated 15-Jul-11 12:12pm

v2

Comments

Sergey Alexandrovich Kryukov 15-Jul-11 23:04pm

This is the reasonable answer; my 5.
Your method could be slightly improved in part of string presentation of the list.

Please see my solution.
--SA

Solution 3

Simple statement :

textBox1.Text = ( ( TimeZoneInfo )lb1.SelectedItem ).ToString ();

good luck :) .

Posted 15-Jul-11 14:14pm

Dev. RoOo7

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Sergey Alexandrovich Kryukov · Accepted Answer · 2011-07-15T17:03:00

The correct and practical method so far is the one by Salmen.

In case the strings shown in dialog box are not perfectly nice, this method could be slightly improved.
First, you need to understand the simple fact: list boxes and combo boxes can populate lists with objects of any type. When the objects are accessed, items should be cast to the type of the object added, as Salmen demonstrated. The only problem is string representation of the item. It is obtained by .NET from what the method object.ToString returns.

Hence, the general method is: to create appropriate type for the list item and, class or structure, and override its ToString method:

C#

internal struct ItemHelper {
   internal ItemHelper(TimeZoneInfo info) { this.fInfo = info; }
   public override string ToString() { return FormatInfo(this.fInfo); }
   internal TimeZoneInfo Info { get fInfo; }
   private TimeZoneInfo fInfo;
   private static FormatInfo(TimeZoneInfo info) {
      return /* info formatted the right way */;
   } //FormatInfo
} //struct ItemHelper

Add items of this type to the list items and cast them back to ItemHelper when time zone info is needed.

—SA

JOAT-MON · Accepted Answer · 2011-07-15T12:33:00

Solution 2

Rather than adding individual time zones, you should get all the time zones on the system:

C#

lb1.Items.AddRange ( TimeZoneInfo.GetSystemTimeZones ().ToArray () );
lb1.DisplayMember = "DisplayName";

Then wherever you need to show the time zone that is selected:

C#

this.textBox1.Text = ( ( TimeZoneInfo )lb1.SelectedItem ).ToString ();

And to set the time on the digital clock:

C#

yourDigitalClockControl.Value = TimeZoneInfo.ConvertTimeFromUtc ( DateTime.UtcNow, ( TimeZoneInfo )lb1.SelectedItem );

Posted 15-Jul-11 12:33pm

JOAT-MON

Updated 15-Jul-11 14:10pm

v4

Comments

77Jeff 15-Jul-11 19:38pm

I am still trying to get the SelectedIndexChanged Event to show the selected timezone with its UtcOffset in a TextBox under the timer1_Tick Event. Thanks for the code reduction.

JOAT-MON 15-Jul-11 20:01pm

I modified my answer to show how this can be done.

77Jeff 15-Jul-11 20:10pm

Thanks, that got me through most of it.

JOAT-MON 15-Jul-11 20:13pm

No problem. I added one more item to show how to convert the time for setting you digital clock control.

77Jeff 15-Jul-11 20:29pm

Thanks again, just cleaning up the mess now... works well.

Sergey Alexandrovich Kryukov 15-Jul-11 23:06pm

Good answer, my 5. It could be slightly improved in part of string representation of items.
Please see my solution.
--SA

Windows Form ListBox Selections

4 solutions

Solution 1

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Solution 2

Solution 3

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