Try/Catch 不停止程序中的 C# Return 语句

Question

I created a Windows form project with a web browser object. I created a method to reading from a CSV file into a list. And once the list is populated and the form loads, the first item in the list will appear in the website's text box.

I'm using a try/catch block to perform error handling. I noticed that if the file is already open it is showing the message box, but the code continues to run once I close the message box.

It is then throwing an Argument Out of Range Exception when the browser navigates to the web page.

Is it correct that the code continues to run. Should I just add additional error handling before navigating the web browser to the website?

private void LoadAccounts()
{
        if (!File.Exists(path))
        {
            MessageBox.Show("File Doesn't Exist");
        }

            try
            {
                using (StreamReader reader = new StreamReader(path))

                    while (!reader.EndOfStream)
                {
                    string line = reader.ReadLine();
                    string[] accountinfo = line.Split(',');
                    accounts.Add(new WaterAccount(accountinfo[0], accountinfo[1], accountinfo[2],accountinfo[3],string.Empty, string.Empty));
                }

            }

            catch (IOException ex)
            {
                MessageBox.Show(ex.Message);
                return;
            }

 }

This is the code block calling LoadAccounts:

public FormWRB()
{
        InitializeComponent();
        LoadAccounts();
        webBrowserWRB.Navigate("https://secure.phila.gov/WRB/WaterBill/Account/GetAccount.aspx");
        buttonExport.Enabled = false;
}

Answer 1

A try catch statement does not stop the program from running, it just affords you the chance to handle an exception. Most commonly logging the exception. Essentially what your code is doing is trying to run a block of code, if it catches an IOException then display the error message in a message box and the return just terminates the execution of the method.

Here's a solution that could work for you.

    private void LoadAccounts()
    {
        if (!File.Exists(path))
        {
            throw new FileNotFoundException($"{path} does not exist");
        }

        using (StreamReader reader = new StreamReader(path))
        {
            while (!reader.EndOfStream)
            {
                string line = reader.ReadLine();
                string[] accountinfo = line.Split(',');
                accounts.Add(new WaterAccount(accountinfo[0], accountinfo[1], accountinfo[2], accountinfo[3], string.Empty, string.Empty));
            }
        }
    }

Then in the code block that handles LoadAccounts()

    try
    {
        LoadAccounts();
        webBrowserWRB.Navigate("https://secure.phila.gov/WRB/WaterBill/Account/GetAccount.aspx");
        buttonExport.Enabled = false;
    }
    catch (FileNotFoundException ex)
    {
        // Do stuff when file not found here...
    }
    catch (IOException ex)
    {
       // Handle other exceptions here
    }

References: return - https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/return try catch - https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/try-catch