列表<string>自定义排序

Question

I currently have a List<string> object that stores following HTML strings, mainly the URLs, eg

List[0] = "<a href='#' id='1'>Banana</a>";
List[1] = "<a href='#' id='2'>Orange</a>";
List[2] = "<a href='#' id='3'>Apple</a>";
List[3] = "<a href='#' id='4'>Mango</a>";
...

And, when I sort the List<string> object, by doing URLList.Sort(); (assume that URLList.Sort(); (assume that URLList object has been instantiated.) , it gives such order, Banana=>Orange=>Apple=>Mango , which is not exactly what I wanted.

I'd like to have it sorted based on the alphabetical order of these fruit, which is like Apple=>Banana=>Mango=>Orange .

So how can I achieve this custom sorting? Any suggestions? Thanks.

Answer 1

If you want a simple way of doing it, and you expect your array to not change too much:

EDITED 11/30/2012

List.Sort((x, y) => x.Substring(x.IndexOf(">") + 1, 1).CompareTo(y.Substring(y.IndexOf(">") + 1, 1)));

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Answer 2

I'd consider turning your List<string> into a List<KeyValuePair<string, string>> . You can populate it with the Key being set to "Banana", "Apple", etc. and the Value being the url itself. Then you can sort on the Key .

Answer 3

Default sorting for strings is alphabetical , which in this case is controlled by the id attribute, since that is the first part of the strings that is different . You would want to use the version of sort which takes a comparison object and provide your own comparison function which correctly parses your tag and returns the order. Alternatively read your HTML tag into a class, and store it as a list of these objects, would make the code more readable.

Answer 4

This is expected. You are sorting simple strings and the first place they vary is at the value of the id attribute.

I assume it's calling ToString() to determine the sort order, so you could try overriding that to return only the inner text. But I really think you need a class here instead of just strings.

Answer 5

I'm new to C# and ASP.NET, but maybe you could use a System.Web.UI.WebControls.HyperLink instead of a string:

List<HyperLink> links = new List<HyperLink>();

links.Add(new HyperLink() { NavigateURL = "#", ID = "1", Text = "Banana" });
links.Add(new HyperLink() { NavigateURL = "#", ID = "2", Text = "Apple" });
links.Add(new HyperLink() { NavigateURL = "#", ID = "3", Text = "Orange" });
links.Add(new HyperLink() { NavigateURL = "#", ID = "4", Text = "Mango" });

links.Sort((x, y) => x.Text.CompareTo(y.Text));

These links can then be appended to another control on your page, such as a <div> etc.:

Control parent = Page.FindControl("id-of-control");
foreach (HyperLink l in links)
    parent.Controls.Add(l);

Answer 6

Because in your list, the string <a href='#' id='1'>Banana</a> contains id attribute, whose value is 1 , it's smaller than <a href='#' id='2'>Orange</a> , whose id value is 2 . So the result of URLList.Sort(); is correct.

I think you need to create your own String class, and override equals function, or implement Comparable interface, then override compare function.