从另一个类的列表中填充组合框

Question

所以我试图通过调用另一个类中的方法来从List填充ComboBox ，该方法将返回List 。

public endStation()
    {
        InitializeComponent();
        startingStation.Items.Add("Test");
        Line CC = new Line();

        foreach (Station station in CC.GetCC())
        {
            startingStation.Items.Add($"{station.Number} {station.Desc}");
        } 
    }
public List<Station> GetCC()                         // Create List of CC Stations
    {
        var CC = new List<Station>();
        int count = 0;
        for (int i = 0; i < Program.file.Count; i++)
        {
            if (Program.file[i].Number.Contains("CC"))
            {
                CC.Insert(count, Program.file[i]);
                count++;
            }
        }
        return CC;
    }

Answer 1

好吧， List<T>没有GetCC()但Line有； 像这样：

private void startingStation_SelectedIndexChanged(object sender, EventArgs e) {
  //TODO: you have to obtain Line instance here
  Line line = new Line();

  // In order to avoid constant redrawing: we want repaint combobox once,
  // after all items being inserted
  startingStation.BeginUpdate();

  try {
    // It is line (not List<T>) that provides GetCC() method
    foreach (Station station in line.GetCC()) {
      // String interpolation - $"..." is more readable than concatenation
      startingStation.Items.Add($"{station.Number} {station.Desc}");
    } 
  }
  finally {
    startingStation.EndUpdate();
  }
}

编辑：您可以在Linq （专为查询而设计）的帮助下改进GetCC()实现：

using System.Linq;

...

class Line : Station {
  ...
  public List<Station> GetCC() {
    return file
      .Where(item => item.Number.Contains("CC"))
      .ToList();
  }
  ...
}