List转Tree（List转树状结构）

网上发现没有简洁明晰的List to Tree代码，众所周知宇宙第一IDE的原因对写了一个C#版本的，后续有机会再写一个java的吧。需要java的可以看一下思路

  1 using System;
  2 using System.Collections.Generic;
  3 using Newtonsoft.Json;
  4 using System.Linq;
  5 
  6 namespace ListToTree
  7 {
  8     class Program
  9     {
 10         static void Main(string[] args)
 11         {
 12             List tree = ListToTree(CreteListNameData(), 0);
 13             string res = JsonConvert.SerializeObject(tree);
 14 
 15 
 16             Console.WriteLine(res);
 17             Console.ReadLine();
 18 
 19 
 20         }
 21         private static List ListToTree(List list, int pid)
 22         {
 23 
 24             if (list == null || list.Count == 0)
 25             {
 26                 return null;
 27             }
 28             else
 29             {
 30                 List treeList = new List();
 31                 GetTreeListByPid(list, pid, treeList);
 32                 return treeList;
 33             }
 34 
 35 
 36         }
 37         private static List GetTreeListByPid(List list, int pid, List treeList)
 38         {
 39 
 40             List listPidName = list.Where(a => a.pid == pid).ToList();
 41             //list.RemoveAll(a => a.pid == pid);
 42             List treeRes = listPidName.Select(a => new Tree() { id = a.id, name = a.name, pid = a.pid }).ToList();
 43             if (treeList == null || treeList.Count == 0)
 44             {
 45                 treeList.AddRange(treeRes);
 46             }
 47            
 48             foreach (var tree in treeRes)
 49             {
 50                 tree.children = GetTreeListByPid(list, tree.id, treeList);
 51             }
 52             return treeRes;
 53 
 54         }
 55         private static List CreteListNameData()
 56         {
 57             List list = new List()
 58             {
 59                 new Name(1,0,"北京"),
 60                 new Name(2,0,"河北"),
 61 
 62                 new Name(3,1,"密云"),
 63                 new Name(4,1,"海淀"),
 64 
 65                 new Name(5,2,"兴隆"),
 66                 new Name(6,2,"邢台"),
 67 
 68                 new Name(7,3,"密云镇1"),
 69                 new Name(8,3,"密云镇2"),
 70                 new Name(9,4,"海淀镇1"),
 71                 new Name(10,4,"海淀镇2"),
 72 
 73                 new Name(11,5,"兴隆镇1"),
 74                 new Name(12,5,"兴隆镇2"),
 75                 new Name(13,6,"邢台镇1"),
 76                 new Name(14,6,"邢台镇2"),
 77             };
 78             return list;
 79         }
 80 
 81 
 82     }
 83     public class Name
 84     {
 85         public int id { set; get; }
 86         public int pid { set; get; }
 87 
 88         public string name { set; get; }
 89         public Name(int id, int pid, string name)
 90         {
 91             this.id = id;
 92             this.pid = pid;
 93             this.name = name;
 94         }
 95 
 96     }
 97     public class Tree
 98     {
 99         public int id { set; get; }
100         public int pid { set; get; }
101 
102         public string name { set; get; }
103         public List children { set; get; } = new List();
104     }
105 }