按文件收集日期排序

Question

我认为 System.Collections.ObjectModel 没有任何排序或排序功能。

我有一个文件列表，我想按文件日期排序。

Dim list AS System.Collections.ObjectModel.ReadOnlyCollection(Of String)
list = My.Computer.FileSystem.GetFiles("C:\SearchFolder" _ 
    , FileIO.SearchOption.SearchByTopLevelOnly _
    , "TheFileName*.txt")

Dim sTheLastFile AS String

sTheLastFile = list.Max()

这将返回最后一个文件，但基于文件名而不是日期。我想我需要补充 .OrderBy(... 就是拿不到那部分。

Answer 1

using System.IO;

public static void Main()
{
    DirectoryInfo di = new DirectoryInfo("c:\\temp\\");
    FileSystemInfo[] files = di.GetFileSystemInfos("*.mp3");
    printFiles(files);

    Array.Sort(files, CompareFileByDate);
    printFiles(files);

}

public static int CompareFileByDate(FileSystemInfo f1, FileSystemInfo f2)
{
    return DateTime.Compare(f1.LastWriteTime, f2.LastWriteTime);
}

public static void printFiles(FileSystemInfo[] files)
{
    foreach(FileSystemInfo file in files)
    {
        Console.WriteLine(file.Name);
    }
    Console.WriteLine("********************************");
}

看看这是否对你有帮助。

我使用了LastWriteTime 属性。您可以选择适合您的（CreationTime 或 LastAccessTime）。

编辑：当然，这可以使用 c# 3.0 转换为更紧凑的语法并支持 lambda 表达式。

编辑2：

from file in new DirectoryInfo(@"c:\temp\").GetFileSystemInfos("*.mp3")
orderby file.LastWriteTime
select file

EDIT3：上述c#代码的vb.net版本

from file in new DirectoryInfo("c:\temp\").GetFileSystemInfos("*.mp3") _
order by file.LastWriteTime _
select file

EDIT4：这是您要找的吗？
这会给你最大。所有 *.mp3 文件的 LastWriteTime 日期。

(from file in new DirectoryInfo("c:\temp\").GetFileSystemInfos("*.mp3") _
order by file.LastWriteTime descending _
select file.LastWriteTime).Take(1)

或

(from file in new DirectoryInfo("c:\temp\").GetFileSystemInfos("*.mp3") _
select file.LastWriteTime).Max()

Answer 2

使用这个类，您可以使用适当的条件对文件进行排序（您必须为您需要的每个条件添加私有帮助程序类 ;-)）

Imports System.IO

Class FilesTools
    Private Class HelperSortByLastWriteTimeAsc
        Implements IComparer(Of FileInfo)

        Public Function Compare(ByVal x As System.IO.FileInfo, _
                                ByVal y As System.IO.FileInfo) As Integer Implements System.Collections.Generic.IComparer(Of System.IO.FileInfo).Compare
            Return Date.Compare(x.LastWriteTime, y.LastWriteTime)
        End Function
    End Class

    Private Class HelperSortByLastWriteTimeDesc
        Implements IComparer(Of FileInfo)

        Public Function Compare(ByVal x As System.IO.FileInfo, _
                                ByVal y As System.IO.FileInfo) As Integer Implements System.Collections.Generic.IComparer(Of System.IO.FileInfo).Compare
            Return Date.Compare(y.LastWriteTime, x.LastWriteTime)
        End Function
    End Class

    Public Shared Function sortByLastTime() As IComparer(Of FileInfo)
        Return New HelperSortByLastWriteTimeAsc
    End Function

    Public Shared Function sortByLastTimeDesc() As IComparer(Of FileInfo)
        Return New HelperSortByLastWriteTimeDesc
    End Function

    Public Shared Function GetFilesSorted(ByVal path As String, _
                                          ByVal sort As IComparer(Of FileInfo)) As FileInfo()
        Dim info As FileInfo()
        info = New DirectoryInfo(path).GetFileSystemInfos()

        Array.Sort(Of FileInfo)(info, sort)

        Return info
    End Function

End Class

Answer 3

要完成此操作，请尝试以下操作...

设置一个实现IComparer 接口的新类。这将用于执行比较。 IComparer 提供了一种自定义集合排序顺序的方法。请注意，下面的示例使用 LastWriteTime 作为比较的基础，但是可以将其更改为您认为合适的任何属性。

Public Class clsCompareFileInfo
    Implements IComparer
    Public Function Compare(ByVal x As Object, ByVal y As Object) As Integer Implements IComparer.Compare
        Dim File1 As FileInfo
        Dim File2 As FileInfo

        File1 = DirectCast(x, FileInfo)
        File2 = DirectCast(y, FileInfo)

        Compare = DateTime.Compare(File1.LastWriteTime, File2.LastWriteTime)
    End Function
End Class

然后，抓取文件集合并执行以下操作以对文件进行相应的排序。

 Dim dirinfo As DirectoryInfo = New DirectoryInfo("C:\SearchFolder")
        Dim allFiles() As FileInfo = dirinfo.GetFiles("TheFileName*.txt", SearchOption.TopDirectoryOnly)
        Array.Sort(allFiles, New clsCompareFileInfo)
        For Each fl As FileInfo In allFiles
            MsgBox(fl.FullName.ToString())
        Next