Exception Handling

Question

I have a browse button which allows users to browse folders, when the folder has been selected it is put into a textbox, the user then clicks a button to open the folder.

What sort of exception handling do I need for the open button? If you click it when there is no path in the textbox the program stops. I tried something like:

if textbox1.text = true;

but didn't work, please help if you know how!

Brandon Lewis · Answer

Thats what I did in mine and it worked :) EDIT: Im still going to see if I cant get it to work the other way. I know I can and it bothers me when I just havent done it lol. Ill get back to you with the working code so you can implement it if you want. Brandon EDIT[2]: Drew I have a question for you. Are you building this program just for fun or are you building it for a client or something? Ive kind of run out of idea's for programs to build myself and I would like to help you out on this particular one your working on. After reviewing some of your coding I would say were really at about the same level of knowledge right now so itd be a learning experience for the both of us!

Drew Taylor · Answer

I got two errors: Operator || cannot be applied to operands of type string and object Possible uninitiated reference comparison I have another idea what if I have an error message if the user clicks the button and there is nothing selected? Would that be easier to do? I added an if else to the button but it breaks on the following line of code: FileStream fsFileInfo = new FileStream(FilePath + selectedFile FileMode.Open FileAccess.Read); Here is the code: if (Convert.ToBoolean(filesListBox.SelectedItem = false )) { MessageBox.Show(Please select a folder); } else { string selectedFile; string header = File Name; //string[] items = text.Split(new char[]{''} StringSplitOptions.RemoveEmptyEntries); //Grab the file name that is selected selectedFile = Convert.ToString(filesListBox.SelectedItem); string fileName = selectedFile; //Open the file and assign a StreamReader to read the contents FileStream fsFileInfo = new FileStream(FilePath + selectedFile FileMode.Open FileAccess.Read); StreamReader srFileInfo = new StreamReader(fsFileInfo); //Finally display the entire contents of the file with a header at start of file fileContentsText.Text = Convert.ToString(header + Environment.NewLine + ************ + Environment.NewLine + fileName + Environment.NewLine + Environment.NewLine + Contents + Environment.NewLine + ************ + Environment.NewLine + srFileInfo.ReadToEnd()); srFileInfo.Close(); fsFileInfo.Close(); this .textBox1.Text=(DateTime.Now.ToShortTimeString() +  File was opened succussfully); }

Brandon Lewis · Answer

Try this: Double click the list box and it will create a listBox1_SelectedIndexChanged() code stub for you to handle the event. Put this code in that event: if(listBox1.SelectedItem = String.Empty || listBox1.SelectedItem = null) { button.Enabled = false; } else if(listBox1.SelectedItem != String.Empty || listBox1.SelectedItem != null) { button.Enabled = true; } I think that will work you might have to tweak it a bit but thats the general idea. It evaluates the listbox contents to see if an item is selected and if it is it enabled the button. And because _SelectedIndexChanged is almost an autonomous event it checks it whenever the contents change the user selects something different or anything else happens to that listBox. I used one and it gave me a few problems in the future but I fixed them easily and it works very dynamically and clean. Just remember if ANYTHING happens to that listbox it will almost definitely trigger the _SelectedIndexChanged event. Good luck! Brandon

David Isaac · Answer

the SelectedIndexChanged event on the list box should allow you to play about with enabling and disabling buttons

Drew Taylor · Answer

Thanks for your replies the code works great! Thanks! I tried something like that earlier but didn't know how. I have a different button which opens highlighted files in a listbox is there a way to have it enabled only when an item is selected?

David Isaac · Answer

Disable the open button until you have populated the text box

Mahesh Chand · Answer

if (textBox1.text.Length { MessageBox.Show(Please select a folder); Return; }