How to fix 'file is in use by another process' error

Question

I've created a program that is able to modify the contents of a .exe.config file (app config) through a datagridview with key value pairs displayed on the datagridview. The problem is, I have a save setting, which replaces the old value with a new value typed by the user. It saves, and next time I open it the file will be overwritten, but I get a 'file is used by another process' error when i try to load the config file to update the user on what the setting has been changed to.

This is the code:

    private XmlDocument m_XmlDoc;

    private FileStream fIn;
    private StreamReader sr;
    private StreamWriter sw;

    private OrderedDictionary m_Settings;

    private void ProgramConfig_Load(object sender, EventArgs e)
    {
        try
        {
            loadconfigfile(GatewayConfiguration.Properties.Settings.Default.Config);

            BindingList<KeyValueType> list = new BindingList<KeyValueType>();
            for (index = 0; index < m_Settings.Count; index++)
            {
                list.Add(new KeyValueType(keys[index], values[index].ToString()));
            }

            var source = new BindingSource();
            source.DataSource = list;
            dataGridView1.DataSource = source;
        }
        catch (Exception ex)
        {
            textBox1.Text = ex.Message;
        }
    }

    public void loadconfigfile(string configfile)
    {
        if (File.Exists(configfile))
        {
            m_XmlDoc = new XmlDocument();
            GatewayConfiguration.Properties.Settings.Default.Config = configfile;
            GatewayConfiguration.Properties.Settings.Default.Save();

            // Error Occurs here at the fIn, telling me that the file is currently in use and cannot be accessed.
            fIn = new FileStream(configfile, FileMode.Open, FileAccess.ReadWrite);
            sr = new StreamReader(fIn);
            sw = new StreamWriter(fIn);
            try
            {
                m_XmlDoc.LoadXml(sr.ReadToEnd());
                loadAppSettings();
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }
        else
        {
            throw new FileNotFoundException(configfile + " does not exist.");
        }
    }

    private void loadAppSettings()
    {
        m_Settings = new OrderedDictionary();
        XmlNodeList nl = m_XmlDoc.GetElementsByTagName("setting");
        foreach (XmlNode node in nl)
        {
            try
            {
                m_Settings.Add(node.Attributes["name"].Value, node.ChildNodes[0].InnerText);
            }
            catch (Exception)
            {
            }
        }
    }

    private void SaveAppSettings_Click(object sender, EventArgs e)
    {
        // saves
        MessageBoxButtons buttons = MessageBoxButtons.YesNo;
        DialogResult result = MessageBox.Show("Overwrite the old values with the new values?", "Save Settings?", buttons);
        if (result == DialogResult.No)
        {
            return;
        }
        int index = 0;
        string[] keys = new string[m_Settings.Keys.Count];
        m_Settings.Keys.CopyTo(keys, 0);
        for (index = 0; index < dataGridView1.Rows.Count; index++)
        {
            if ((string)dataGridView1[2, index].Value != string.Empty)
            {
                setAppSetting(keys[index], (string)dataGridView1[2, index].Value);
            }
        }
        // Updates datagrid by loading configfile again
        loadconfigfile(GatewayConfiguration.Properties.Settings.Default.Config);
        textBox1.Text = "Settings Saved. You may now exit.";
        m_savecounter++;
        dataGridView1.Update(); 
        dataGridView1.Refresh();
    }

The error occurs at the loadconfigfile function under SaveAppSettings. It tells me that it cannot access the file because the file is used by another process. Is there something I need to do before I can open the file again and display it to the user?

Many thanks,

Tf.rz

Answer 1

How about this at the end of loadconfigfile()

fIn.Close();

You essentially need to close any stream you opened once you are done.