Question

如何使用lambda表达式搜索作为对象的字典值。（使用下面的课程）

Dictionary<int, House[]> houseDict = new Dictionary<int, House[]>();

假设有3个元素，每个元素有10个房子。

如何根据元素找到属于客户的房屋/房屋，例如

这是我到目前为止所得到的，但不知道如何缩小到houseNumber

houseDict[0].Where(s => s.GetCustomer() == theCustomer)

这不起作用 - ＆gt; houseDict[0].SelectMany(s => s.GetHouseNumber()).Where(c => c.GetCustomer() == theCustomer);

public class House
{
  private static int _instances = 0;
  private int houseNumber;
  private bool sold;
  private bool reserved;
  private bool free;

  private Customer customer;

  public House(int theHouseNumber)
  {
      houseNumber = theHouseNumber;
      sold = false;
      reserved = false;
      free = true;
  }

  ~House()
  {
      _instances--;
  }

  public void SellHouse(Customer buyer)
  {
      customer = buyer;
      sold = true;
      free = false;
  }

  public void ReserveHouse(Customer reserver)
  {
      customer = reserver;
      free = false;
      sold = false;
      reserved = true;
  }

  public void ReturnHouse()
  {
      customer = null;
      free = true;
      sold = false;
      reserved = false;
  }

  public void BuyReservedHouse(Customer buyer)
  {
      sold = true;
  }

  public bool IsFree()
  {
      return free;
  }

  public bool IsReserved()
  {
      return reserved;
  }


  public int GetHouseNumber()
  {
      return houseNumber;
  }

  public void SetCustomer(Customer buyer)
  {
      customer = buyer;
  }

  public Customer GetCustomer()
  {
      return customer;
  }

}

public class Customer
{
    private static int _instances = 0;
    private String name;
    private int id = 0;

  public Customer(String customerName)
  {
    _instances++;
    name = customerName;
    id = _instances;
  }

  public String GetName()
  {
    return name;
  }

  public int GetId()
  {
    return id;
  }
}

Answer 1

如果特定客户的房屋可以分布在许多ID上，那么您需要搜索所有价值集：

houseDict.SelectMany(kvp => kvp.Value)
         .Where(s => s.GetCustomer() == theCustomer)

这假设theCustomer 实例与多个值集合中的实例相同。如果您根据ID进行匹配，则可以使用：

houseDict.SelectMany(kvp => kvp.Value)
         .Where(s => s.GetCustomer().GetId() == theCustomer.GetId())

Answer 2

听起来你想要搜索字典，而不仅仅是字典中的第一项。只要您有using System.Linq;语句，您就应该能够这样做：

houseDict.ToList().Where(s => s.Value.GetCustomer() == theCustomer);

这会将您的词典更改为列表＆gt;，您可以使用lambda。

使用lambda进行字典数组值搜索

2 个答案: