C# 如何仅在以下情况下返回值；“好的”；点击

我已经创建了一个custimazibale提示符

public static class Prompt
{
    public static string ShowDialog(int columnnumber, string columnname)
    {
        Form prompt = new Form();
        prompt.Width = 500;
        prompt.Height = 150;
        prompt.FormBorderStyle = FormBorderStyle.FixedDialog;
        prompt.Text = columnname;
        prompt.StartPosition = FormStartPosition.CenterScreen;
        Label textLabel = new Label() { Left = 50, Top = 20 };
        ComboBox comboBox = new ComboBox() { Left = 50, Top = 50, Width = 400 };
        comboBox.Items.AddRange(new string[] { "a","b","c" });
        comboBox.DropDownStyle = ComboBoxStyle.DropDownList;
        comboBox.SelectedItem = columnname;
        Button confirmation = new Button() { Text = "Ok", Left = 350, Width = 100, Top = 80 };
        confirmation.Click += (sender, e) => { prompt.Close(); };
        textLabel.Text = "Colonne " + (columnnumber + 1).ToString() + " : " + columnname;
        prompt.Controls.Add(comboBox);
        prompt.Controls.Add(confirmation);
        prompt.Controls.Add(textLabel);
        prompt.AcceptButton = confirmation;
        prompt.ShowDialog();
        prompt.AcceptButton = confirmation;

        return comboBox.Text;
    }
}

然后单击标题时，我在主窗体中调用它

private void dataGridView1_ColumnHeaderMouseClick(object sender, DataGridViewCellMouseEventArgs e)
{
     dt.Columns[e.ColumnIndex].ColumnName = Prompt.ShowDialog(e.ColumnIndex, dataGridView1.Columns[e.ColumnIndex].Name);
}

问题是，即使单击“关闭”按钮，我的文本也会更改。

---

但我希望只有当用户单击“确定”按钮时，它才会更改。

您可以在确认时设置布尔值，如果未确认，则使用该值返回null，如下所示：

public static string ShowDialog(int columnnumber, string columnname)
{
    Form prompt = new Form();
    prompt.Width = 500;
    prompt.Height = 150;
    prompt.FormBorderStyle = FormBorderStyle.FixedDialog;
    prompt.Text = columnname;
    prompt.StartPosition = FormStartPosition.CenterScreen;
    Label textLabel = new Label()
    {
        Left = 50,
        Top = 20
    };
    ComboBox comboBox = new ComboBox()
    {
        Left = 50,
        Top = 50,
        Width = 400
    };
    comboBox.Items.AddRange(new string[] { "a", "b", "c" });
    comboBox.DropDownStyle = ComboBoxStyle.DropDownList;
    comboBox.SelectedItem = columnname;
    Button confirmation = new Button()
    {
        Text = "Ok",
        Left = 350,
        Width = 100,
        Top = 80
    };

    bool confirmed = false;

    confirmation.Click += (sender, e) =>
    {
        prompt.Close();
        confirmed = true;
    };
    textLabel.Text = "Colonne " + (columnnumber + 1).ToString() + " : " + columnname;
    prompt.Controls.Add(comboBox);
    prompt.Controls.Add(confirmation);
    prompt.Controls.Add(textLabel);
    prompt.AcceptButton = confirmation;
    prompt.ShowDialog();
    prompt.AcceptButton = confirmation;

    return confirmed ? comboBox.Text : null;
}

using(Form prompt = new Form())
{
    //Initialize the components of your form

    DialogResult result = prompt.ShowDialog();
    if(result == DialogResult.OK)
    {
       //return whatever it is you want to return
    }
}

您的调用代码将需要检查返回值是否为null，并且仅在返回值不为null时执行操作。

您可以计算返回值，如果返回值不为null，则返回

null

：

public static class Prompt
{
    public static string ShowDialog(int columnnumber, string columnname)
    {
        using (Form prompt = new Form())
        {
            // other code
            return prompt.DialogResult == DialogResult.OK ? comboBox.Text : null;
        }
    }
}

然后用另一种方法：

private void dataGridView1_ColumnHeaderMouseClick(object sender, EventArgs e)
{
    var result = Prompt.ShowDialog(e.ColumnIndex, 
                                   dataGridView1.Columns[e.ColumnIndex].Name);
    if (result != null)
        dt.Columns[e.ColumnIndex].ColumnName = result;
}

在

提示符中

应相应地设置

对话框结果

：

confirmation.Click += (sender, e) =>
    {
        prompt.DialogResult = DialogResult.OK;
        prompt.Close();
    };

---

提示：而不是

result！=空

您也可以使用

！String.IsNullOrWhiteSpace（result）

仅在输入内容时更新列名。

我会选择以下内容：

public static string ShowDialog(int columnnumber, string columnname)
{
    Form prompt = new Form();
    prompt.Width = 500;
    prompt.Height = 150;
    prompt.FormBorderStyle = FormBorderStyle.FixedDialog;
    prompt.Text = columnname;
    prompt.StartPosition = FormStartPosition.CenterScreen;
    Label textLabel = new Label()
    {
        Left = 50,
        Top = 20
    };
    ComboBox comboBox = new ComboBox()
    {
        Left = 50,
        Top = 50,
        Width = 400
    };
    comboBox.Items.AddRange(new string[] { "a", "b", "c" });
    comboBox.DropDownStyle = ComboBoxStyle.DropDownList;
    comboBox.SelectedItem = columnname;
    Button confirmation = new Button()
    {
        Text = "Ok",
        Left = 350,
        Width = 100,
        Top = 80
    };

    bool confirmed = false;

    confirmation.Click += (sender, e) =>
    {
        prompt.Close();
        confirmed = true;
    };
    textLabel.Text = "Colonne " + (columnnumber + 1).ToString() + " : " + columnname;
    prompt.Controls.Add(comboBox);
    prompt.Controls.Add(confirmation);
    prompt.Controls.Add(textLabel);
    prompt.AcceptButton = confirmation;
    prompt.ShowDialog();
    prompt.AcceptButton = confirmation;

    return confirmed ? comboBox.Text : null;
}

using(Form prompt = new Form())
{
    //Initialize the components of your form

    DialogResult result = prompt.ShowDialog();
    if(result == DialogResult.OK)
    {
       //return whatever it is you want to return
    }
}

---

在表单中，您可以通过

prompt.DialogResult=DialogResult.OK

和其他一些选项（DialogResult.Cancel、DialogResult.Retry等）设置DialogResult

这可能比根据我的答案设置局部变量要好。一旦设置了DialogResult，表单就会隐藏，但是，如果表单位于使用对话框的内部，则在您处理完DialogResult后，如果我没有弄错的话，它将被处理。@meansomerandoms:True，只要您使用

ShowDialog

。使用

Show

（这里不是这种情况）只会设置属性。此外，表单仅被隐藏，并且在这种情况下，

Close

不会自动调用，因此，如果有人正在侦听关闭事件，则会使用“手动调用”…我最后使用了此解决方案，这样更好。非常感谢。