如何从文本文件中获取键和值并在组合框中设置值

Question

我的窗口窗体应用程序中有两个组合框。第一个组合框显示我已经从 xls 文件的数据库中获得的国家/地区的城市名称。组合框像这样显示城市名称 -

     Berlin
     Munich 
     Stuttgart //etc.

现在我编写了一个文本文件，其中包含该地点的兴趣点列表。我的文本文件看起来像

Berlin,Berlin Wall,Brandenburg Gate,Reichstag Building
Munich,Nymphenburg palace,Museum Island,Marienplatz
Stuttgart,Old Castle,Staatsgalerie Stuttgart,schlossplatz stuttgart //etc

现在我希望当一个地方出现在第一个组合框中时，所有 POI 项目将在第二个组合框中以列表形式自动生成，就像我点击柏林时第二个组合框会显示

  Berlin Wall
  Brandenburg Gate
  Reichstag Building

但我不确定如何继续执行此操作。

我的代码是-

ComboBox 1 按以下方式填写

 class PlaceList
   {
      public static ComboBox Combo_list = new ComboBox();
      public static DataGridView dataTable = new DataGridView();

      public static 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_list.Items.Add(data.Rows[i]["City"]);
        }
        string Place_Json = "Place_List:" + JsonConvert.SerializeObject(data, Formatting.Indented);
        File.WriteAllText(Saving_path, Place_Json);

       }
    }
  }

然后我从 From1.cs 中调用它就像这样

 public partial class Form1 : Form
 {
    public Form1()
    {

        InitializeComponent();
        PlaceList.Combo_list = comboBox1;


    }
 }

Answer 1

您需要加载文件并在字典中逐行构建一个条目，其中键是带有城市名称的字符串，值是带有 POI 的字符串列表。然后，当您从组合中选择一个城市时，只需使用该字符串作为关键字来搜索您的字典

例如，这是一个完整的示例，您可以使用 LinqPAD 进行测试，并展示如何读取您的 txt 文件并构建一个全局变量，让您的兴趣点以城市名称为关键字

Form f;
ComboBox cboCities;
ComboBox cboPoi;
Dictionary<string, List<string>> poi = new Dictionary<string, List<string>>();
void Main()
{
    f = new Form();
    cboCities = new ComboBox();
    cboCities.DropDownStyle = ComboBoxStyle.DropDownList;
    cboCities.Items.AddRange(new string[] { "Berlin", "Munich", "Stuttgart"});
    cboCities.SelectedIndexChanged += cboCities_SelectedIndexChanged;
    f.Controls.Add(cboCities);
    cboPoi = new ComboBox();
    cboPoi.Location = new System.Drawing.Point(0, 30);
    f.Controls.Add(cboPoi);
    foreach (string line in File.ReadLines(@"D:\temp\poi.txt"))
    {
        string[] parts = line.Split(new char[] { ',' }, StringSplitOptions.RemoveEmptyEntries);
        poi.Add(parts[0], new List<string>(parts.Skip(1)));
    }
    f.ShowDialog();
}
void cboCities_SelectedIndexChanged(object sender, EventArgs e)
{
    string txt = cboCities.SelectedItem.ToString();
    if (poi.ContainsKey(txt))
    {
        List<string> points = poi[txt];
        cboPoi.Items.Clear();
        cboPoi.Text = string.Empty;
        cboPoi.Items.AddRange(points.ToArray());
    }
}

Answer 2

这是我编辑的答案：

 private void button1_Click(object sender, EventArgs e)
    {

        LoadKeys();

    }
    Dictionary<string, List<string>> poi = new Dictionary<string, List<string>>();
    private void LoadKeys()
    {

       foreach (string line in File.ReadLines("TextFile1.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));
                }

    }

    void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
    {
        if (comboBox1.SelectedItem != null)
        {
            string txt = comboBox1.SelectedItem.ToString();
            if (poi.ContainsKey(txt))
            {
                List<string> points = poi[txt];
                comboBox2.Items.Clear();
                comboBox2.Items.AddRange(points.ToArray());
            }
        }
    }