Question

我有两个与一个和另一个相关的课程，一个城镇有很多人。

public class Town
{
    List<People> collectionOfPeople;

    public string town { get; set; }

    public Town()
    {
        townName = "";

        collectionOfPeople = new List<People>();
        collectionOfPeople.Add(new People());
    }

    public Town(string tmp_townName)
    {
        townName = tmp_townName;

        collectionOfPeople = new List<People>();
        collectionOfPeople.Add(new People("Daniel Smith", "22"));
    }
}

在List中构建Town的实例，以及与之关联的记录之后，我想在表单上显示结果。

    private int numberOfPeople;
    private int currentPeopleShown;
    private int numberOfTown;
    private int currentTown;
    private List<People> peopleList;
    private List<Town> townList;

    // ************************* Methods/Functionality
    private void LoadData()
    {
        txt_townName.Text = (townList[0]).townName;
        txt_peopleName.Text = (peopleList[currentPeopleShown]).name;

        numberOfPeople = peopleList.Count();
        currentPeopleShown = 0;
    }

如何引用List中的List，显示或计算其中的记录数（town0 ..显示people1,2,3等）？

Answer 1

您必须将列表公开为属性

public List<People> CollectionOfPeople { get; set; }
^                                      ^ ^    ^    ^

然后引用它：

var people = myTown.CollectionOfPeople;

Answer 2

您可以使用SelectMany（...）将所有嵌套项合并为单个可枚举

townList.SelectMany(t=>t.collectionOfPeople).Count();

Answer 3

如何在List中引用List，以显示或计算其中的记录数。（town0 ..显示人员1,2,3等）

foreach (Town town in townList)
  foreach (People people in town.collectionOfPeople)
    MessageBox.Show(people.Name);

关联类（列表中的列表）

3 个答案: