C＃填充列表的最佳方法 <Class> 从清单 <string>

Question

I have very simple code which explains itself.

List<string> Files = new List<string>( Directory.EnumerateFiles(PathLocation));

However I now wish to make life complicated and I have a file object.

public class File
{
    public int FileId { get; set; }
    public string Filename { get; set; }
}

Is there an optimal way to populate the string property of the class, ie is there a better way than using a foreach loop or similar?

Answer 1

You can use LINQ Select to replace foreach loop:

List<File> files = Files.Select(s => new File() { FileId = id, Filename = s})
                        .ToList();

But needless to create new List to optimize your code:

List<File> files = Directory.EnumerateFiles(PathLocation)
                            .Select(s => new File() { FileId = id, Filename = s})
                            .ToList();

MSDN is here

Answer 2

当然：

List<File> Files = Directory.EnumerateFiles(PathLocation).Select(f=> new File { FileId = /*...*/, Filename = f }).ToList();

Answer 3

You can map the contents of Files into a List<File> :

var files = Files.Select(f => new File { Filename = f })
                 .ToList();

The same using LINQ syntax:

var query = from f
            in Files 
            select new File { Filename = f };

var files = query.ToList();

Answer 4

List<File> bigList;
var stringList = bigList.Select(f=>f.Filename);