![](/img/trans.png)
[英]Why gettype for two different objects of same type has same reference
[英]Why sometimes 2 objects reference the same but not always
遵循最后一個答案: 將平面集合轉換為分層集合的遞歸方法?
我想使用相同的方法 CreateTree 但使用另一個對象而不是層次結構:ItemNode:
public class ItemNode
{
public string Id { get; set; }
public Item Item { get; set; }
public ICollection<ItemNode> Children { get; set; }
}
以及 Item 的定義:
public class Item
{
public string ID { get; set; }
public string Name { get; set; }
public int Level { get; set; }
public string ParentId { get; set; }
}
這里是帶有 ItemNode 的 CreateTree 方法:
static List<ItemNode> CreateTreeItems(IEnumerable<ItemNode> nodes)
{
Dictionary<string,ItemNode> idToNode = nodes.ToDictionary(n => n.Id, n => n);
List<ItemNode> roots = new List<ItemNode>();
ItemNode root = null;
foreach (var n in nodes)
{
if (n.Item.ParentId == null)
{
if (root != null)
{
roots.Add(root);
}
root = n;
continue;
}
ItemNode parent = idToNode[n.Item.ParentId];
//if (!idToNode.TryGetValue(n.Item.ParentId, out parent))
//{
// //Parent doesn't exist, orphaned entry
//}
parent?.Children.Add(n);
// RETURNS FALSE WHEREAS IN THE ORIGINAL METHOD IT RETURNS TRUE
var test = Object.ReferenceEquals(parent, root);
Debug.WriteLine(test);
}
if (root == null)
{
//There was no root element
}
roots.Add(root);
return roots;
}
它不起作用,因為 parent 和 root 沒有引用同一個對象(而在原始方法中,它確實如此)。 我想這與我在 ItemNode 類中添加了一個 Item 屬性有關。 但我不知道如何修復它。
謝謝 !
為什么您希望根節點和父節點引用相等? 每個根節點都可能是父節點,但並非每個父節點都是根節點。
可能存在引用相等的情況,但這在很大程度上取決於nodes
集合的排序順序。 實際上,當根節點放置在第一級子節點之前時,您會看到引用相等的情況。
我想你的問題在別處,例如,如果Nodes
集合根本沒有根節點,它可能無法工作。
這是示例,請在此處嘗試https://dotnetfiddle.net/4r52xP
using System;
using System.Collections.Generic;
using System.Linq;
public class Hierarchy
{
public Hierarchy(string iD, string name, int level, string parentID, string topParent)
{
ID = iD;
Name = name;
Level = level;
ParentID = parentID;
Children = new HashSet<Hierarchy>();
}
public string ID { get; set; }
public string Name{ get; set; }
public int Level { get; set; }
public string ParentID { get; set; }
public ICollection<Hierarchy> Children { get; set; }
}
public class Program
{
static Hierarchy CreateTree(IEnumerable<Hierarchy> Nodes)
{
var idToNode = Nodes.ToDictionary(n => n.ID, n => n);
Hierarchy root = null;
foreach (var n in Nodes)
{
if (n.ParentID == null)
{
if (root != null)
{
//there are multiple roots in the data
}
root = n;
continue;
}
Hierarchy parent = null;
if (!idToNode.TryGetValue(n.ParentID, out parent))
{
//Parent doesn't exist, orphaned entry
}
parent.Children.Add(n);
Console.WriteLine("ReferenceEquals: {0}", Object.ReferenceEquals(parent, root));
}
if (root == null)
{
//There was no root element
}
return root;
}
public static void Main()
{
Console.WriteLine("Test #1");
List<Hierarchy> l = new List<Hierarchy>();
l.Add(new Hierarchy("295152","name1",1,null, null)); // <-root node at the top of the list
l.Add(new Hierarchy("12345","child1",2,"295152", null));
l.Add(new Hierarchy("54321","child2",2,"295152", null));
l.Add(new Hierarchy("44444","child1a",3,"12345", null));
l.Add(new Hierarchy("33333","child1b",3,"12345", null));
l.Add(new Hierarchy("22222","child2a",3,"54321", null));
l.Add(new Hierarchy("22221","child2b",3,"54321", null));
l.Add(new Hierarchy("22002","child2c",3,"54321", null));
l.Add(new Hierarchy("20001","child2a2",4,"22222", null));
l.Add(new Hierarchy("20101","child2b2",4,"22222", null));
CreateTree(l);
Console.WriteLine("\nTest #2");
l = new List<Hierarchy>();
l.Add(new Hierarchy("12345","child1",2,"295152", null));
l.Add(new Hierarchy("54321","child2",2,"295152", null));
l.Add(new Hierarchy("44444","child1a",3,"12345", null));
l.Add(new Hierarchy("33333","child1b",3,"12345", null));
l.Add(new Hierarchy("22222","child2a",3,"54321", null));
l.Add(new Hierarchy("22221","child2b",3,"54321", null));
l.Add(new Hierarchy("22002","child2c",3,"54321", null));
l.Add(new Hierarchy("20001","child2a2",4,"22222", null));
l.Add(new Hierarchy("20101","child2b2",4,"22222", null));
l.Add(new Hierarchy("295152","name1",1,null, null)); // <-root node at the bottom of the list
CreateTree(l);
}
}
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.