如何获取richTextBox来读取列表框

Question

what i'm trying to do is this i have a listBox that shows all .txt files in a folder but I want to be able to click a .txt in the listBox and have my richTextBox show the text from that .txt file. Code to show files:

    private void Scripts_Load(object sender, EventArgs e)
    {
        DirectoryInfo dinfo = new DirectoryInfo(@"scripts");
        FileInfo[] Files = dinfo.GetFiles("*.txt");
        foreach (FileInfo file in Files)

            list.Items.Add(file.Name);
    }

As for the code to show in textBox I have tried many internet answers and got nowhere main errors being Argument 1: cannot convert from 'object' to 'string' The closest I have got is with this

    //Get the FileInfo from the ListBox Selected Item
FileInfo SelectedFileInfo = (FileInfo) listBox.SelectedItem;  

//Open a stream to read the file  
StreamReader FileRead = new StreamReader(SelectedFileInfo.FullName);

//Read the file to a string
string FileBuffer = FileRead.ReadToEnd();

//set the rich text boxes text to be the file
richTextBox.Text = FileBuffer;

//Close the stream so the file becomes free!
FileRead.Close();

It Crashes saying: `System.InvalidCastException: 'Unable to cast object of type 'System.String' to type 'System.IO.FileInfo'.'

There was already a comment saying that this happens and the guy replied saying change line 1 to FileInfo SelectedFileInfo = new FileInfo(listBox1.SelectedItem); this failed saying Argument 1: cannot convert from 'object' to 'string' `

I did it YAY!!!

        private async void listBox1_SelectedIndexChanged(object sender, EventArgs e)
    {
        string value1 = list.SelectedItem.ToString();
        richTextBox1.Text = value1;
        using (StreamReader sr = new StreamReader("scripts\\" + value1))
        {
            {
                String line = await sr.ReadToEndAsync();
                richTextBox1.Text = line;
            }
        }
    }

Answer 1

The reason is that in your Listbox are strings stored.

You musst try to convert them.

        var filename as listBox.SelectedItem as string;
        if(string.IsNullOrWhiteSpace(filename))
        {
            return;
        }
        var path = Path.Combine(@"C:\", filename);
        var fileinfo = new FileInfo(path);

Answer 2

I did it, it took me some time but I realized that I could get the text and move it to the textbox I didn't think that would help because I wanted the document not the name but then I put the Var as the file path, Here:

        private async void listBox1_SelectedIndexChanged(object sender, EventArgs e)
    {
        string value1 = list.SelectedItem.ToString();
        richTextBox1.Text = value1;
        using (StreamReader sr = new StreamReader("scripts\\" + value1))
        {
            {
                String line = await sr.ReadToEndAsync();
                richTextBox1.Text = line;
            }
        }
    }