Sort ObservableCollection 通过C＃

Question

我低于ObservableCollection<string>。我需要按字母顺序[。

private ObservableCollection<string> _animals = new ObservableCollection<string>
{
    "Cat", "Dog", "Bear", "Lion", "Mouse",
    "Horse", "Rat", "Elephant", "Kangaroo", "Lizard", 
    "Snake", "Frog", "Fish", "Butterfly", "Human", 
    "Cow", "Bumble Bee"
};

我尝试过_animals.OrderByDescending。但是我不知道如何正确使用它。
_animals.OrderByDescending(a => a.<what_is_here_?>);

我该怎么做？

Answer 1

简介

Answer 2

/// <summary>
/// Inserts an item into a list in the correct place, based on the provided key and key comparer. Use like OrderBy(o => o.PropertyWithKey).
/// </summary>
public static void InsertInPlace<TItem, TKey>(this ObservableCollection<TItem> collection, TItem itemToAdd, Func<TItem, TKey> keyGetter)
{
    int index = collection.ToList().BinarySearch(keyGetter(itemToAdd), Comparer<TKey>.Default, keyGetter);
    collection.Insert(index, itemToAdd);
}

Answer 3

我对某个类别的字段（距离）进行了排序。

Answer 4

这里是Shimmy的稍有变化，用于收集已经实现了众所周知的Move的类。在这种情况下，“ order by”选择器是隐式的。

Answer 5

我知道这是一个古老的问题，但是“ sort observablecollection”的第一个Google搜索结果是Google的结果，因此我认为值得离开我的两分钱。

Answer 6

我创建了ObservableCollection的扩展方法

Answer 7

我看着这些东西，得到了整理，然后像上面那样打破了装订。提出了这个解决方案，尽管它比大多数解决方案简单，但似乎可以满足我的要求，,,

Answer 8

这是一个

public static void MySort<TSource,TKey>(this ObservableCollection<TSource> observableCollection, Func<TSource, TKey> keySelector)
    {
        var a = observableCollection.OrderBy(keySelector).ToList();
        observableCollection.Clear();
        foreach(var b in a)
        {
            observableCollection.Add(b);
        }
    }

，它会根据更改自动对自身进行排序，仅在必要时才触发排序，并且仅触发单个move collection更改操作。

Answer 9

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Collections.Specialized;
using System.Linq;

namespace ConsoleApp4
{
  using static Console;

  public class SortableObservableCollection<T> : ObservableCollection<T>
  {
    public Func<T, object> SortingSelector { get; set; }
    public bool Descending { get; set; }
    protected override void OnCollectionChanged(NotifyCollectionChangedEventArgs e)
    {
      base.OnCollectionChanged(e);
      if (SortingSelector == null 
          || e.Action == NotifyCollectionChangedAction.Remove
          || e.Action == NotifyCollectionChangedAction.Reset)
        return;

      var query = this
        .Select((item, index) => (Item: item, Index: index));
      query = Descending
        ? query.OrderBy(tuple => SortingSelector(tuple.Item))
        : query.OrderByDescending(tuple => SortingSelector(tuple.Item));

      var map = query.Select((tuple, index) => (OldIndex:tuple.Index, NewIndex:index))
       .Where(o => o.OldIndex != o.NewIndex);

      using (var enumerator = map.GetEnumerator())
       if (enumerator.MoveNext())
          Move(enumerator.Current.OldIndex, enumerator.Current.NewIndex);


    }
  }


  //USAGE
  class Program
  {
    static void Main(string[] args)
    {
      var xx = new SortableObservableCollection<int>() { SortingSelector = i => i };
      xx.CollectionChanged += (sender, e) =>
       WriteLine($"action: {e.Action}, oldIndex:{e.OldStartingIndex},"
         + " newIndex:{e.NewStartingIndex}, newValue: {xx[e.NewStartingIndex]}");

      xx.Add(10);
      xx.Add(8);
      xx.Add(45);
      xx.Add(0);
      xx.Add(100);
      xx.Add(-800);
      xx.Add(4857);
      xx.Add(-1);

      foreach (var item in xx)
        Write($"{item}, ");
    }
  }
}

的参数是一个返回要排序的键的函数。在您的情况下，关键是字符串本身：

Answer 10

var result = _animals.OrderByDescending(a => a);

Answer 11

_animals.OrderByDescending(a => a.<what_is_here_?>);

Answer 12

此扩展方法无需对整个列表进行排序。