How to get the selectedItems on top of the list?

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Hello Experts,

I have a windows forms. I have to create a multiple selection which is like checked dropdownlist. I want to get the selected Items on the top once it is selected. And clear the rest of the list. Is it possible? I don't have idea about how to do this.
Here is my code for Checkeddropdown list Datasource

VB

Dim dsclass As DataSet = dbDev.GetClass()
   CheckedListBox1.DataSource = dsclass.Tables(0)
   CheckedListBox1.DisplayMember = "RMCCLS"
   CheckedListBox1.ValueMember = "RMCCLS"

After I check the boxes in the drop down list, I need to get the selected items on Top.

If the idea is bad and not amicable. Could you please share any such ideas?

Posted 7-Apr-15 6:04am

sudevsu

Updated 7-Apr-15 6:40am

v2

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Sergey Alexandrovich Kryukov 7-Apr-15 12:33pm

To avoid confusions, please add the tag "System.Windows.Forms". Once UI is concerned, always add the tags related to the application type and UI library you want to use; and/or specify full type names.
—SA

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Sascha Lefèvre · Answer 1 · 2015-04-07T16:08:00

If it's ok for you to remove the rows not only from being displayed but also from the original DataTable, then do this:

C#

// get the DataTable "back":
DataTable dataTable = ((DataView)CheckedListBox1.DataSource).Table;

// the selected Rows are "in" .CheckedItems in form of DataRowViews:
IEnumerable<DataRow> selectedRows = CheckedListBox1.CheckedItems.Cast<DataRowView>().Select(x => x.Row);

// create a HashSet of the selected DataRows for fast lookup:
HashSet<DataRow> selectedRowsHashset = new HashSet<DataRow>(selectedRows);

// loop over the DataRows in the DataTable in reverse order:
// (required because we're going to remove DataRows)
for (int rowIndex = dataTable.Rows.Count - 1; rowIndex >= 0; rowIndex--)
{
    // remove the DataRow at rowIndex if it is not among the selected rows:
    if (!selectedRowsHashset.Contains(dataTable.Rows[rowIndex]))
    {
        dataTable.Rows.RemoveAt(rowIndex);
    }
}

If you only want the rows removed from being displayed, then do this:

C#

// get the DataTable "back":
DataTable sourceDataTable = ((DataView)CheckedListBox1.DataSource).Table;

// create a structural clone:
DataTable newDataTable = sourceDataTable.Clone();

// loop over the selected DataRows:
foreach (DataRow sourceRow in CheckedListBox1.CheckedItems.Cast<DataRowView>().Select(x => x.Row))
{
    // create a new DataRow and copy the values of the selected DataRow:
    DataRow newRow = newDataTable.NewRow();
    for (int columnIndex = 0; columnIndex < newDataTable.Columns.Count; columnIndex++)
    {
        newRow[columnIndex] = sourceRow[columnIndex];
    }
    // add the DataRow-copy to the new DataTable:
    newDataTable.Rows.Add(newRow);
}

// set the new DataTable as new DataSource for the CheckedListBox:
CheckedListBox1.DataSource = newDataTable;