In C# WPF, is there a way to make it sort to the top of the listview whenever a new item is added?

Question

I'm making a WPF app that implements a folder explorer.
And I want to add a new folder item to the top of the folder list view when the new folder button is pressed.
So I put a code that adds a sortdirection to sort by date, folder, and filename.
However, although the new folder is added to the top, there is a problem that the sort order of existing items is changed.
So, I would like to know how to make the existing items are sorted on top while new items are added. I know it is possible by using customsort, but it is difficult to implement with my skills.
Can anyone help me?

Below is the function code to add a new folder.

private void LocalNewFolder(int set_flag)
        {
            if (set_flag > 2) return;
            if (uiList_textbox[set_flag - 1].Text == "") return;

            var str_newfolder = "";
            NewFolderInputBox Local_Mk_NewFolder = new NewFolderInputBox();
            if (Local_Mk_NewFolder.ShowDialog() == true)
            {
                str_newfolder = Local_Mk_NewFolder.Text_NewFolder.Text;

                if (str_newfolder == "")
                    return;
            }
            else
            {
                return;
            }
            string path_newfolder = uiList_textbox[set_flag - 1].Text + "\\" + str_newfolder;
            //string path_newfolder = this.line_set1_local.Text + "\\" + str_newfolder;

            if (!Directory.Exists(path_newfolder))
            {
                Directory.CreateDirectory(path_newfolder);
            }
            else
            {
                return;
            }

            var folderdate = Directory.GetLastWriteTime(path_newfolder);

            if (set_flag == 1)
            {
                source_Local_path_all1.Insert(0, new Local_path_all1()
                {
                    local_all_date = folderdate,
                    local_all_extension = "folder",
                    local_all_filename = str_newfolder,
                    local_all_size = "",
                    local_all_src = "Resources/icon_folder.png"
                });                                
                this.list_set1_local_all.Items.SortDescriptions.Clear();
                this.list_set1_local_all.Items.SortDescriptions.Add(new SortDescription("local_all_date", ListSortDirection.Descending));
                this.list_set1_local_all.Items.SortDescriptions.Add(new SortDescription("local_all_extension", ListSortDirection.Descending));
                this.list_set1_local_all.Items.SortDescriptions.Add(new SortDescription("local_all_filename", ListSortDirection.Ascending));
                this.list_set1_local_all.Items.Refresh();
            }
            else if (set_flag == 2)
            {
                source_Local_path_all2.Insert(0, new Local_path_all2()
                {
                    local_all_date = folderdate,
                    local_all_extension = "folder",
                    local_all_filename = str_newfolder,
                    local_all_size = "",
                    local_all_src = "Resources/icon_folder.png"
                });
                this.list_set2_local_all.Items.SortDescriptions.Clear();
                this.list_set2_local_all.Items.SortDescriptions.Add(new SortDescription("local_all_date", ListSortDirection.Descending));
                this.list_set2_local_all.Items.SortDescriptions.Add(new SortDescription("local_all_extension", ListSortDirection.Descending));
                this.list_set2_local_all.Items.SortDescriptions.Add(new SortDescription("local_all_filename", ListSortDirection.Ascending));
                this.list_set2_local_all.Items.Refresh();
            }            
        }

Answer 1

Hi,@JunYoungLee . What is the code for your NewFolderInputBox , list_set1_local_all and uiList_textbox ? Is it possible to show the complete code that reproduces the problem for analysis?

Possible solutions1:
Use Insert instead of Add :

collection.Insert(0, newItem);  

Note that it's slower than Add since it has to shift all items by 1 position. It might be an issue if the list is very big.

Possible solutions2:
Adapt CustomSort for your needs:

• You could give all new items an extreme value for the property used in IComparer object for sorting, e.G. int.MaxValue or string.Empty.
• Or create an additional property IsNew and include it into comparing process.

For more details, you could try and see if the solutions here work for you.

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