AppSettings.Update C# (CSharp) Method

    void Update()
    {
    }

    private void cmdUpdate_Click(object sender, System.EventArgs e)
    {
        // Update an existing item.
        try
        {
            if (this.txtSettingKey.Text == string.Empty)
            {
                MessageBox.Show("You must enter a value for the key.", this.Text, MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
                this.txtSettingKey.Select();
                return;
            }

            if (this.txtSettingValue.Text == string.Empty)
            {
                MessageBox.Show("You must enter a value for the value field.", this.Text, MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
                this.txtSettingValue.Select();
                return;
            }

            mcustAppSet = new AppSetting(this.txtSettingKey.Text, this.txtSettingValue.Text);
            mcustAppSettings.Update(mcustAppSet);

            this.ListCustomSettings();

            MessageBox.Show("Existing setting updated.", this.Text, MessageBoxButtons.OK, MessageBoxIcon.Information);
        }
        catch (Exception exp)
        {
            MessageBox.Show(exp.Message, exp.Source, MessageBoxButtons.OK, MessageBoxIcon.Error);
        }
    }