c# - 为具有 KeyValuePair 列表的 ComboBox 选择最初选择的值作为 DataSource

Question

我正在从 List 创建一个组合框的 KeyValuePair<int, string> .到目前为止，它在向用户提供描述性名称同时返回数字 ID 方面效果很好。
但是，无论我尝试什么，我都无法选择最初选择的值。

public StartUpForm()
{
    InitializeComponent();

    FlowLayoutPanel flowLayout = new FlowLayoutPanel(); //This is necessary to protect the table, which is for some reason collapsing...
    flowLayout.FlowDirection = FlowDirection.TopDown;
    flowLayout.AutoSize = true;
    flowLayout.AutoSizeMode = AutoSizeMode.GrowAndShrink;

    var comboBox = new ComboBox();

    {
        var choices = new List<KeyValuePair<int, string>> ();
        choices.Add(new KeyValuePair<int, string>(1, "hello"));
        choices.Add(new KeyValuePair<int, string>(2, "world"));
        comboBox.DataSource = choices;
        comboBox.ValueMember = "Key";
        comboBox.DisplayMember = "Value";
        flowLayout.Controls.Add(comboBox);
    }
    Controls.Add(flowLayout);

    //None of these work:
    comboBox.SelectedValue = 2;
    comboBox.SelectedValue = 2.ToString();
    comboBox.SelectedValue = new KeyValuePair<int, string>(2, "world");
    comboBox.SelectedValue = "world";
    comboBox.SelectedItem = 2;
    comboBox.SelectedItem = 2.ToString();
    comboBox.SelectedItem = new KeyValuePair<int, string>(2, "world");
    comboBox.SelectedItem = "world";

    return;
}

结果总是一样的:

如何在 ComboBox 中选择最初选择的值使用 List<KeyValuePair<int, string>> 作为数据源？

Answer 1

绑定(bind)在构造函数中不能很好地工作，所以尝试将 ComboBox 声明移动到表单范围并尝试使用 OnLoad 覆盖:

ComboBox comboBox = new ComboBox();

protected override void OnLoad(EventArgs e) {
  comboBox.SelectedValue = 2;
  base.OnLoad(e);
}