Question

在我的代码中，我从一个大的.xls文件中获取城市名称和人口编号。我在窗口表单应用程序的datagridview表中设置这些值。然后我只提取城市名称并将其设置为第一个Combobox。 fisrt组合框项目看起来像这样 -

    Flensburg
    Kiel
    Lübeck

然后我制作一个文本文件，其中包含该城市的名称和有趣的地方列表。我的txt文件看起来像这样。

Flensburg;Nordertor;Naval Academy Mürwik;Flensburg Firth
Kiel;Laboe Naval Memorial;Zoological Museum of Kiel University;Kieler    Förde;German submarine U-995;Sparkassen-Arena;Aquarium GEOMAR;Old Botanical Garden, Kiel;Holstein-Stadion;Botanischer Garten der Christian-Albrechts-Universität zu Kiel;Schwentine;Schulensee;Lanker See;Postsee;Rosensee
Lübeck;Holstentor;St. Mary's Church, Lübeck;Passat (ship);Burgtor;Lübeck Museum of Theatre Puppets;Trave;St. Catherine's Church, Lübeck;Lübeck Cathedral;St. Anne's Museum Quarter, Lübeck;Behnhaus;Behnhaus;Theater Lübeck;Ratzeburger See;Bucu;Hemmelsdorfer See;Stadion an der Lohmühle;Dassower See

现在我实现了一个字典来根据第一个组合框更改第二个组合框值。例如当第一个组合框展示弗伦斯堡时，它将在第二个组合框上显示弗伦斯堡的所有地方。然而，代码是完美的，直到它在主Form中实现，即Form1.cs。但是现在我尝试用另一个类用单独的方法编写它。所以现在我面临问题，因为我无法修复objectsender和evetaverage问题并将其传递给Form1.cs。

我的数据类代码是 -

       namespace POIList
        {
                public class POI
                {

                    public static ComboBox Combo_list1 = new ComboBox();
                    public static ComboBox Combo_list2 = new ComboBox();
                    public static DataGridView dataTable = new DataGridView();
                    Dictionary<string, List<string>> poi = new Dictionary<string, List<string>>();

                    public void List()
                    {

                        var startPath = Application.StartupPath;
                        string folderName = Path.Combine(startPath, "POI_List");
                        System.IO.Directory.CreateDirectory(folderName);
                        string SavedfileName = "POI_list.json";
                        var Saving_path = Path.Combine(folderName, SavedfileName);

                        string fileName = "Zensus_Gemeinden_org.xlsx";
                        var path = Path.Combine(startPath, fileName);

                        String name = "Gemeinden_31.12.2011_Vergleich";
                        String constr = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" +
                                       path + ";Extended Properties='Excel 12.0 XML;HDR=YES;';";

                        OleDbConnection con = new OleDbConnection(constr);
                        OleDbCommand oconn = new OleDbCommand("Select [3] as City,[4] as Population, * From [" + name + "$D7:E11300] Where [4] > 10000", con);
                        con.Open();

                        OleDbDataAdapter sda = new OleDbDataAdapter(oconn);
                        DataTable data = new DataTable();

                        sda.Fill(data);
                        dataTable.DataSource = data;

                        for (int i = 0; i < data.Rows.Count; i++)
                        {
                            Combo_list1.Items.Add(data.Rows[i]["City"]);
                        }
                        string Place_Json = "Place_List:" + JsonConvert.SerializeObject(data, Formatting.Indented);
                        File.WriteAllText(Saving_path, Place_Json);

                        foreach (string line in File.ReadLines("POIList.txt"))
                        {
                            string[] parts = line.Split(new char[] { ';' }, StringSplitOptions.RemoveEmptyEntries);
                            poi.Add(parts[0], new List<string>());
                            poi[parts[0]] = new List<string>(parts.Skip(1));


                        }

                    }

                   public void Combo_list_SelectedIndexChanged(object sender, EventArgs e)
                    {
                        if (Combo_list1.SelectedItem != null)
                        {
                            string txt = Combo_list1.SelectedItem.ToString();
                            if (poi.ContainsKey(txt))
                            {
                                List<string> points = poi[txt];
                                Combo_list2.Items.Clear();
                                Combo_list2.Items.AddRange(points.ToArray());

                            }
                        }
                    }



                }
            }

Form1.cs是

 namespace TouristPlace
  {
   public partial class Form1 : Form
  {
    public Form1()
    {
        InitializeComponent();
        POI.Combo_list1 = comboBox1;
        POI.dataTable = dataGridView1;

        POI poi1 =new POI();
        poi1.List();

        POI poi2 = new POI();
        //poi2.Combo_list_SelectedIndexChanged();

    }

    private void button1_Click(object sender, EventArgs e)
    {
    }
    public string ComboText1
    {
        get { return comboBox1.Text; }
        set { comboBox1.Text = value; }
    }
    public string ComboText2
    {
        get { return comboBox2.Text; }
        set { comboBox2.Text = value; }
    }

Answer 1

查看您的代码，我无法看到您将回调分配给Combo_list1.SelectedIndexChanged事件的位置。也许这就是问题所在。

尝试添加：

Combo_list1.SelectedIndexChanged += Combo_list_SelectedIndexChanged;

在POI类中的

，例如在List（）函数中。确保仅调用List（）函数一次，否则将多次调用回调函数。如果你不能确定，你可以这样做：

Combo_list1.SelectedIndexChanged -= Combo_list_SelectedIndexChanged;
Combo_list1.SelectedIndexChanged += Combo_list_SelectedIndexChanged;

无论如何，正如其他人在OP中告诉你的那样，你应该将ComboBox移到表单中，将它们留在数据类中是不安全的。

使用c＃，组合框的selectedindex更改无法正常工作

1 个答案: