Question

I’m loading values from file via File.ReadAllText, straight into ListBox1

the file is .txt – Comma Separated.

HealthyFood.Txt

content:

Dairy,Fruits,Vegetables,Whole Grains

to populate Listbox1 (LstBox_HealthyCat) in its simple way (no Condition applied ) With little Help of my Helper-Method actually, so I will not have repeat my code for the other files(:

public string GetFileContent(string FileName)
{
    string Filecontent = "";
    string ExtTXT = ".txt";
    string initialDir = @"G:\RobDevI5-3xRaid-0\Projects\WindowsFormsApplication1\bin\x64\Debug\HealthFood\";

    Filecontent = File.ReadAllText(intialDir + FileName + ExtTXT);
    return Filecontent;

}

string[] HealthyFood = GetFileContent(HealthyFood).Split(',');
LstBox_HealthyCat.Items.AddRange(HealthyFood);

So now the result is ListBoxMainCategory will be

Dairy

Fruits

Vegetables

Whole Grains

So Far it’s good example for new developers

My Question is, next step I would like to populate
The Sub-Category oF HealthyFood e.g Fruits

fruits.txt

content:

Apple,Banana,Cherry,Dates

So when I will click on Main Category: Fruits
it will populate ListBox2 with selection of ListBox1
and rest of items availble in listBox1 as well(when clicked).

alternative to my

 Filecontent = File.ReadAllText(intialDir + FileName + ExtTXT);

Tim Schmelter’s code:

 System.IO.Path.Combine(initialDir, item + ExtTXT); 

path combine … nice one !

Answer 1

So if i understood your requirement correctly, you want to fill the second ListBox according to the SelectedItem(s) of ListBox1. For instance, if fruit was selected then fruits.txt should be used and so on. Then this might help you:

const string initialDir = @"G:\RobDevI5-3xRaid-0\Projects\WindowsFormsApplication1\bin\x64\Debug\HealthFood\";
const string ExtTXT = ".txt";

private void listBox1_SelectedIndexChanged(object sender, EventArgs e)
{
    listBox2.Items.Clear();
    foreach (String item in listBox1.SelectedItems)
    {
        String path = System.IO.Path.Combine(initialDir, item + ExtTXT);
        if(System.IO.File.Exists(path))
        {
            listBox2.Items.AddRange(System.IO.File.ReadAllText(path).Split(','));
        }
    }
}