C #: How to save a list of elements, such as Combobox, into a .NET settings file?

Question

C #: How to save a list of elements, such as Combobox, into a .NET settings file?

Answer 1

The only type of collection that allows you to use the settings constructor is System.Collections.ArrayList. If you use an ArrayList, all of its element types must be serializable (have the [Serializable] attribute or implement System.Runtime.Serialization.ISerializable.)

Here is some code to get data from an ArrayList (named cboCollection) in the settings in the combo box and vice versa.

    private void Form1_Load(object sender, EventArgs e)
    {
        if (Settings.Default.cboCollection != null)
            this.comboBox1.Items.AddRange(Settings.Default.cboCollection.ToArray());
    }


    private void Form1_FormClosing(object sender, FormClosingEventArgs e)
    {
        ArrayList arraylist = new ArrayList(this.comboBox1.Items);
        Settings.Default.cboCollection = arraylist;
        Settings.Default.Save();
    }

    //A button to add items to the ComboBox
    private int i;
    private void button1_Click(object sender, EventArgs e)
    {
        this.comboBox1.Items.Add(i++);
    }

Answer 2

If you are talking about user preferences for the application, I would skip the combo box and save the values ​​in a separation line:

StringBuilder sb = new StringBuilder();
foreach(var item in combo.Items){
  sb.Append(item.ToString() + ";");
}
Properties.Settings.MyListSetting = sb.ToString();

, , , .

, !

Answer 3

Windows Forms objects cannot be serialized. Therefore, you cannot serialize and store them in a binary formatted file. You need to save the combobox values ​​manually in a file.

string comboboxFileName = @"c:\workDir\settings.settings";

private void saveComboboxInFile (String comboboxFileName )
{
   //--------------------------------------------------------
   //- Store the combobox values in a file. 1 value = 1 line
   //--------------------------------------------------------
   try
    {
        using (StreamWriter comboboxsw = new StreamWriter(comboboxFileName))
        {
            foreach (var cfgitem in comboBox.Items)
            {
                comboboxsw.WriteLine(cfgitem);
            }
        } // End Using`
    }
    catch (Exception e)
    {
       //process exception
    }
}



private void reloadCombboxFromFile (string  comboboxFileName )
   {
    //-------------------------------------------------
    //- Read the values back into the combobox
    //------------------------------------------------- 
        try
        {
            using (StreamReader comboboxsr = new StreamReader(comboboxFileName))
            {
                 while (!comboboxsr.EndOfStream)
                 {
                      string itemread = comboboxsr.ReadLine();
                      comboBox.Items.Add(itemread);
                 }
            } // End Using
      }
      catch (DirectoryNotFoundException dnf)
      {
         // Exception Processing
      }
      catch (FileNotFoundException fnf)
      {
         // Exception Processing
      }
      catch (Exception e)
      {
         // Exception Processing
      }
   }