为什么这个程序的输出不是我认为的

Question

我对这个程序的输出有点困惑。这是代码中的一个真实场景，但我已将其缩短为以下内容：

class Program 
{ 
    static void Main(string[] args) 
    { 
     Dummy obj = new Dummy(); 
     obj.FillList(); 
     obj.MyPublicMethod(); 

    } 
} 

public class Dummy 
{ 
    public Dummy() 
    { 
     NamesCollection = new List<string>(); 
    } 
    public ICollection<string> NamesCollection { get; set; } 

    private List<string> _names; 
    public List<string> Names 
    { 
     get 
     { 
      //return _names ?? 
      //  (_names = NamesCollection.ToList()); 

      if (ReferenceEquals(_names, null)) 
      { 
       _names = NamesCollection.ToList(); 
      } 

      if (_names.Count != NamesCollection.Count) 
      { 
       _names.Clear(); 
       _names.Add("Aamir"); 
      } 
      return _names; 
     } 
     set { _names = value; } 
    } 


    public void FillList() 
    { 
     this.NamesCollection.Add("Atif"); 
     this.NamesCollection.Add("Ali"); 
     this.NamesCollection.Add("haris"); 

     this.Names.Add("Asif"); 
    } 

    public void MyPublicMethod() 
    { 
     foreach (var item in Names) 
     { 
      Console.WriteLine(item); 
     } 
     //I am thinking that output should be: 
     //Atif 
     //Ali 
     //haris 
     //Aamir 
     //But the output that I am getting is only: 
     //Aamir 
    } 
} 

Answer 1

问题出在MyPublicMethod方法中。当您执行foreach (var item in Names){}时，获取方法Names执行。 _names.Count = 4，但是NamesCollection.Count = 3。所以_names被清除。并添加'Aamir'。