VB/CLASS問題：只顯示所有記錄的最後一條記錄

Question

我嘗試獲取每張專輯的歌曲列表。我已經建立2類：相冊&歌，所以我可以爲波紋管組織他們：

Public Class Album 
    Sub New() 
     Entered = Now 
    End Sub 
    Public Entered As DateTime 
    Public AlbumName As String = "" 
    Public Artist As String = "" 
    Public YearReleased As Integer = 1900 
    Public Songs As New List(Of Song) 
End Class 

Public Class Song 
    Public SongName As String = "" 
    Public SongLength As String = "" 
End Class 

然而，當我添加歌曲專輯，我總是進入了最後一首歌曲。這裏是輸出結果的例子。

Protected Sub Test() 
    Dim vAlbum As New Album 
    Dim vsong As New Song 

    vAlbum.AlbumName = "Test 01" 
    vAlbum.Artist = "Jackie" 
    vAlbum.YearReleased = 2012 

    vsong.SongName = "Exit" 
    vsong.SongLength = "1.5" 
    vAlbum.Songs.Add(vsong) 

    vsong.SongName = "Exit II" 
    vsong.SongLength = "2.5" 
    vAlbum.Songs.Add(vsong) 

    For Each sSong As Song In vAlbum.Songs 
     Response.Write(sSong.SongName + "<br>") 
    Next 
End Sub 

OUTPUT：

退出II

退出II

我有谷歌，但到處都找不到磺酰基的最新記錄顯示，所有歌曲。

任何幫助，歡迎。

謝謝，弗雷德

Answer 1

你添加相同Song兩次，只是改變其領域。

你應該使用這樣的事情：

Dim vAlbum As New Album 

vAlbum.AlbumName = "Test 01" 
vAlbum.Artist = "Jackie" 
vAlbum.YearReleased = 2012 

Dim vsong As New Song 
vsong.SongName = "Exit" 
vsong.SongLength = "1.5" 
vAlbum.Songs.Add(vsong) 

vsong As New Song ' create a new instance of Song 
vsong.SongName = "Exit II" 
vsong.SongLength = "2.5" 
vAlbum.Songs.Add(vsong) 

或更好，使用對象初始化或創建一個constructur即採取一切必要的值：

Public Class Song 

    Public SongName As String = "" 
    Public SongLength As String = "" 

    Public Sub new(name as String, length as String) 
     SongName = name 
     SongLength = length 
    End Sub 

End Class 

... 

vAlbum.Songs.Add(new Song("Exit", "1.5")) 
vAlbum.Songs.Add(new Song("Exit II", "2.5")) 

Answer 2

經典參考書的問題。你的vsong永遠是同一個對象。您需要實例化一個新的實例：

... 
vAlbum.Songs.Add(vsong) 
vsong = new Song() 
vsong.SongName = "Exit II" 
...