Sorting ListViewItems by Date, Number or String

As shown in this article, you can sort a ListView items by date.

This code is very slow however.

Here’s an improved version which also handles sorting of numbers.

First create a static Dictionary in your MainForm, like this:

internal static Dictionary<int, ListViewColumnSorter.cDataType> columnType = new Dictionary<int,ListViewColumnSorter.cDataType>();

cDataType

is an enum:
public enum cDataType

{

    number, datetime, text

}

When re-loading your ListView, or when changing the columns, clear the Dictionary, because the data type of the column can change.

public int Compare(object x, object y)

{

    int compareResult;

    ListViewItem listviewX, listviewY;

    // Cast the objects to be compared to ListViewItem objects

    listviewX = (ListViewItem)x;

    listviewY = (ListViewItem)y;

    // Compare the two items

    //Determine data type of object

    string objectX = listviewX.SubItems[ColumnToSort].Text;

    string objectY = listviewY.SubItems[ColumnToSort].Text;

    cDataType dType = cDataType.text;

    if (!MainForm.columnType.TryGetValue(ColumnToSort, out dType))

    {

        long tempLong;

        DateTime tempDateTime;

        if (Int64.TryParse(objectX, out tempLong))

        {

            MainForm.columnType.Add(ColumnToSort, cDataType.number);

        }

        else if (DateTime.TryParse(objectX, out tempDateTime))

        {

            MainForm.columnType.Add(ColumnToSort, cDataType.datetime);

        }

        else

        {

            MainForm.columnType.Add(ColumnToSort, cDataType.text);

        }

    }

    switch (MainForm.columnType[ColumnToSort])

    {

        case cDataType.number:

            compareResult = ObjectCompare.Compare(Convert.ToInt64(objectX), Convert.ToInt64(objectY));

            break;

        case cDataType.datetime:

            compareResult = ObjectCompare.Compare(DateTime.Parse(objectX), DateTime.Parse(objectY));

            break;

        default:

            compareResult = ObjectCompare.Compare(objectX, objectY);

            break;

    }

   

    // Calculate correct return value based on object comparison

    if (OrderOfSort == SortOrder.Ascending)

    {

        // Ascending sort is selected, return normal result of compare operation

        return compareResult;

    }

    else if (OrderOfSort == SortOrder.Descending)

    {

        // Descending sort is selected, return negative result of compare operation

        return (-compareResult);

    }

    else

    {

        // Return '0' to indicate they are equal

        return 0;

    }

}