Question

再试一次问我的问题 - 上次搞砸了。

这是我的示例代码：

小形式，仅包含按钮和组合框：

public partial class question : Form
{
public question()
{
    InitializeComponent();
}

private void button1_Click(object sender, EventArgs e)
{
    comboBox1.DataSource = new List<string>() { "a", "b", "c" };
}

private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{
    MessageBox.Show("In comboBox1_SelectedIndexChanged");
    throw new Exception();
}
}

项目的Program类调用question表单并处理异常：

 class Program
{
static void Main(string[] args)
{
    try
    {
        Application.EnableVisualStyles();
        Application.SetCompatibleTextRenderingDefault(false);

        // Add the event handler for handling UI thread exceptions to the event.
        Application.ThreadException += new ThreadExceptionEventHandler(MyCommonExceptionHandlingMethod);

        // Set the unhandled exception mode to force all Windows Forms errors to go through
        // our handler.
        Application.SetUnhandledExceptionMode(UnhandledExceptionMode.CatchException);

        // Add the event handler for handling non-UI thread exceptions to the event. 
        AppDomain.CurrentDomain.UnhandledException +=
            new UnhandledExceptionEventHandler(CurrentDomain_UnhandledException);

        Application.Run(new question());
    }
    catch (Exception ex)
    {
        Console.WriteLine(ex.Message + "3");
    }
}
private static void MyCommonExceptionHandlingMethod(object sender, ThreadExceptionEventArgs t)
{
    Console.WriteLine(t.Exception.Message + "1");
}

private static void CurrentDomain_UnhandledException(object sender, UnhandledExceptionEventArgs e)
{
    Console.WriteLine(((Exception)e.ExceptionObject).Message + "2");
}
}

现在，当单击该按钮时，事件“SelectedIndexChanged”将上升（并显示messageBox）但将忽略该异常。只有当用户手动选择组合框中的另一个索引时，才会处理异常。

问题是，如何处理这些例外呢？

Answer 1

即使使用try-catch，

也无法拦截异常：

try
{
    comboBox1.DataSource = new List<string>() {"a", "b", "c"};
}
catch (Exception ex)
{
}

似乎ComboBox忽略了设置DataSource时发生的异常：

ListControl.DataSource source code

try 
{
    SetDataConnection(value, displayMember, false);
} catch 
{
    DisplayMember = "";
}

ComboBox.DataSource uses base ListControl implementation

C＃winforms在特定情况下不会捕获异常

1 个答案: