排序 ObservableCollection<string>通过 C# [英] Sort ObservableCollection&lt;string&gt; through C#

问题描述

我有以下 ObservableCollection.我需要按字母顺序排序.

I have below ObservableCollection<string>. I need to sort this alphabetically.

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"
};

我尝试了 _animals.OrderByDescending.但我不知道如何正确使用它.

I tried _animals.OrderByDescending. But I don't know how to use it correctly.

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

我该怎么做?

推荐答案

简介

基本上，如果需要显示排序的集合，请考虑使用CollectionViewSource 类:将其Source 属性分配(绑定")到源集合 — ObservableCollection 类的一个实例.

Introduction

Basically, if there is a need to display a sorted collection, please consider using the CollectionViewSource class: assign ("bind") its Source property to the source collection — an instance of the ObservableCollection<T> class.

这个想法是 CollectionViewSource 类提供了 CollectionView 类 的实例.这是一种投影"原始(源)集合，但应用了排序、过滤等.

The idea is that CollectionViewSource class provides an instance of the CollectionView class. This is kind of "projection" of the original (source) collection, but with applied sorting, filtering, etc.

参考文献:

• 如何:使用 XAML 中的视图对数据进行排序和分组.
• WPF 的 CollectionViewSource.

WPF 4.5 引入了实时整形"；CollectionViewSource 的功能.

WPF 4.5 introduces "Live Shaping" feature for CollectionViewSource.

参考文献:

• WPF 4.5 新功能:Live Shaping.
• CollectionViewSource.IsLiveSorting 属性.
• 将数据重新定位为数据的值更改(实时整形).

如果仍然需要对 ObservableCollection<T> 类的实例进行排序，这里是如何完成的.ObservableCollection 类本身没有 sort 方法.但是，可以重新创建集合以对项目进行排序:

If there still a need to sort an instance of the ObservableCollection<T> class, here is how it can be done. The ObservableCollection<T> class itself does not have sort method. But, the collection could be re-created to have items sorted:

// Animals property setter must raise "property changed" event to notify binding clients.
// See INotifyPropertyChanged interface for details.
Animals = new ObservableCollection<string>
    {
        "Cat", "Dog", "Bear", "Lion", "Mouse",
        "Horse", "Rat", "Elephant", "Kangaroo",
        "Lizard", "Snake", "Frog", "Fish",
        "Butterfly", "Human", "Cow", "Bumble Bee"
    };
...
Animals = new ObservableCollection<string>(Animals.OrderBy(i => i));

其他详细信息

请注意OrderBy() 和OrderByDescending() 方法(与其他LINQ 扩展方法一样)不要修改源集合！相反，它们创建一个新序列(即实现 IEnumerable 接口的类的新实例).因此，有必要重新创建集合.

Additional details

Please note that OrderBy() and OrderByDescending() methods (as other LINQ–extension methods) do not modify the source collection! They instead create a new sequence (i.e. a new instance of the class that implements IEnumerable<T> interface). Thus, it is necessary to re-create the collection.

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