Vb.net VB：对象“；由于其保护级别而无法访问”；（Visual Studio 2012）

我在VB（Visual Studio 2012）中使用此

搜索按钮时遇到问题：

Form1.VB中的此代码：

Private Sub SearchButton_Click(sender As Object, e As EventArgs) Handles SearchButton.Click 
    Dim results As Artist 
    results = Array.SearchArray(artistArray(), SearchTextBox.Text) 
End Sub 

我得到一个错误，
artistArray
由于其保护级别而无法访问

我是VB新手，所以我肯定这是我做错了什么，但我找不到它

我检查了拼写、可见性（
Public
）等

array.vb目前：

Public Class Array 
    Public artistArray() As Artist 
    Public searchResults(artistArray.Length) As Artist 
    Dim searchString As String 

    Public Function SearchArray(ByVal artistArray(), searchString) As Artist() 
        Dim x As Integer ' artist index variable for loop 
        Dim index As Integer = 0 ' index for results 
        For x = 0 To artistArray.GetUpperBound(0) 
            Dim temp As Artist = artistArray(x) 
            If temp.Name.ToLower().Contains(searchString.ToLower()) Then 
                searchResults(index) = artistArray(x) ' if search hit then add current item to result array 
                index += 1 ' and incr. result index 
            End If 
         Next 
         ReDim Preserve searchResults(index) 
         Return searchResults 
    End Function 

    ' ...
End Class

Public
与global不同。事实上，VB.NET甚至不支持
Global
变量，这是严格意义上的旧VB6。即使它是
公共的
，它的作用域仍然是
数组
类，因此您必须作为该类的属性访问if。但是，它也是一个实例属性，这意味着它是每个
数组
对象（即实例）的成员，而不是类本身的成员，例如：

Dim first As Artist = Array.artistArray(0)  ' Does not work

但是：

如果要使其成为共享属性，这意味着它将是类本身的成员，而不是该类的每个实例，因此，实际上是全局的，则需要添加
shared
关键字，如下所示：

Public Class Array
    Public Shared arrayArtist() As Artist
    ' ...
End Class

Dim first As Artist = Array.artistArray(0)  ' Works now

Public Class ArtistBusiness
    Public Shared Artists() As Artist

    Public Shared Function SearchArtists(artists() As Artist, searchString As String) As Artist()
        Dim results As New List(Of Artist)()
        For Each i As Artist In artists
            If i.Name.IndexOf(searchString, StringComparison.CurrentCultureIgnoreCase) >=0 Then
                results.Add(i)
            End If
        Next
        Return results.ToArray()
    End Function
End Class

Private Sub SearchButton_Click(sender As Object, e As EventArgs) Handles SearchButton.Click 
    Dim results() As Artist 
    results = ArtistBusiness.SearchArtists(ArtistBusiness.Artists, SearchTextBox.Text) 
End Sub

Public Shared Function SearchArtists(artists() As Artist, searchString As String) As Artist()
    artists.Select(Function(x) x.Name.IndexOf(searchString, StringComparison.CurrentCultureIgnoreCase) >= 0).ToArray()
End Function

然后，您将能够从项目中的任何位置访问它，如下所示：

Public Class Array
    Public Shared arrayArtist() As Artist
    ' ...
End Class

Dim first As Artist = Array.artistArray(0)  ' Works now

Public Class ArtistBusiness
    Public Shared Artists() As Artist

    Public Shared Function SearchArtists(artists() As Artist, searchString As String) As Artist()
        Dim results As New List(Of Artist)()
        For Each i As Artist In artists
            If i.Name.IndexOf(searchString, StringComparison.CurrentCultureIgnoreCase) >=0 Then
                results.Add(i)
            End If
        Next
        Return results.ToArray()
    End Function
End Class

Private Sub SearchButton_Click(sender As Object, e As EventArgs) Handles SearchButton.Click 
    Dim results() As Artist 
    results = ArtistBusiness.SearchArtists(ArtistBusiness.Artists, SearchTextBox.Text) 
End Sub

Public Shared Function SearchArtists(artists() As Artist, searchString As String) As Artist()
    artists.Select(Function(x) x.Name.IndexOf(searchString, StringComparison.CurrentCultureIgnoreCase) >= 0).ToArray()
End Function

当然，拥有全局变量几乎总是一个糟糕的设计决策，但这是另一个主题

所有这些都有点让人困惑，因为您正在调用类
Array
。从技术上讲，如果您真的愿意，您可以这样做，但我不建议这样做，因为.NET Framework已经包含了一个名为
Array
的类，这是非常基本的

此外，没有理由将搜索结果存储在类的字段中。如果将其范围限定为搜索方法的本地，则会更好。如果对每个
循环使用
，并使用
列表
，则会更简单，如下所示：

Public Class Array
    Public Shared arrayArtist() As Artist
    ' ...
End Class

Dim first As Artist = Array.artistArray(0)  ' Works now

Public Class ArtistBusiness
    Public Shared Artists() As Artist

    Public Shared Function SearchArtists(artists() As Artist, searchString As String) As Artist()
        Dim results As New List(Of Artist)()
        For Each i As Artist In artists
            If i.Name.IndexOf(searchString, StringComparison.CurrentCultureIgnoreCase) >=0 Then
                results.Add(i)
            End If
        Next
        Return results.ToArray()
    End Function
End Class

Private Sub SearchButton_Click(sender As Object, e As EventArgs) Handles SearchButton.Click 
    Dim results() As Artist 
    results = ArtistBusiness.SearchArtists(ArtistBusiness.Artists, SearchTextBox.Text) 
End Sub

Public Shared Function SearchArtists(artists() As Artist, searchString As String) As Artist()
    artists.Select(Function(x) x.Name.IndexOf(searchString, StringComparison.CurrentCultureIgnoreCase) >= 0).ToArray()
End Function

然后，你可以这样称呼它：

Public Class Array
    Public Shared arrayArtist() As Artist
    ' ...
End Class

Dim first As Artist = Array.artistArray(0)  ' Works now

Public Class ArtistBusiness
    Public Shared Artists() As Artist

    Public Shared Function SearchArtists(artists() As Artist, searchString As String) As Artist()
        Dim results As New List(Of Artist)()
        For Each i As Artist In artists
            If i.Name.IndexOf(searchString, StringComparison.CurrentCultureIgnoreCase) >=0 Then
                results.Add(i)
            End If
        Next
        Return results.ToArray()
    End Function
End Class

Private Sub SearchButton_Click(sender As Object, e As EventArgs) Handles SearchButton.Click 
    Dim results() As Artist 
    results = ArtistBusiness.SearchArtists(ArtistBusiness.Artists, SearchTextBox.Text) 
End Sub

Public Shared Function SearchArtists(artists() As Artist, searchString As String) As Artist()
    artists.Select(Function(x) x.Name.IndexOf(searchString, StringComparison.CurrentCultureIgnoreCase) >= 0).ToArray()
End Function

甚至在我的例子中加入globals都让我感到痛苦，但事实就是这样。注意，我将
ToLower.Contains
更改为
IndexOf
，因为考虑到某些区域性问题，这样更安全。我还将click事件处理程序中的
results
变量更改为数组，因为该方法返回的是数组

通过使用LINQ，您还可以进一步简化代码，如下所示：

Public Class Array
    Public Shared arrayArtist() As Artist
    ' ...
End Class

Dim first As Artist = Array.artistArray(0)  ' Works now

Public Class ArtistBusiness
    Public Shared Artists() As Artist

    Public Shared Function SearchArtists(artists() As Artist, searchString As String) As Artist()
        Dim results As New List(Of Artist)()
        For Each i As Artist In artists
            If i.Name.IndexOf(searchString, StringComparison.CurrentCultureIgnoreCase) >=0 Then
                results.Add(i)
            End If
        Next
        Return results.ToArray()
    End Function
End Class

Private Sub SearchButton_Click(sender As Object, e As EventArgs) Handles SearchButton.Click 
    Dim results() As Artist 
    results = ArtistBusiness.SearchArtists(ArtistBusiness.Artists, SearchTextBox.Text) 
End Sub

Public Shared Function SearchArtists(artists() As Artist, searchString As String) As Artist()
    artists.Select(Function(x) x.Name.IndexOf(searchString, StringComparison.CurrentCultureIgnoreCase) >= 0).ToArray()
End Function

但是我建议你在开始做任何花哨的事情之前，花更多的时间学习基础知识。
你的整个代码可以被一行
LINQ
替换

Public artists As Artist()

Public Function FindArtists(searchString As String) As Artist()
    Return artists.Where(Function(a) a.Name.ToLower().Contains(searchString)).ToArray()
End Function

你写的代码没有意义。
Array
类上没有方法
SearchArray
。如果您试图编写一个扩展方法，那么这也不正确。这可能是因为“Public artistArray（）As Artist”在array.vb中，您是否尝试过这样做：results=array.SearchArray（array.artistArray（），SearchTextBox.Text）
System.array
和您的
数组
之间是否存在冲突？尝试重命名您的类，使其更具描述性。示例：
Class ArtistArray继承了（艺术家的）收藏
，因为
SearchArray
不是静态的，所以您的
Array.SearchArray（…）
将导致编译错误--您确定代码正常吗？顺便说一句，类的名称“Array”是一个坏主意。您的函数返回
Artist（）
，并且您正在将结果分配给类型
Artist
。注意到区别了吗？谢谢你的解释。我现在正在学习VB的基础知识，教授希望以某种方式完成。我会根据你的建议，让你知道我的想法。在2013年，这个答案可能还可以，但我认为LINQ已经死了。这是一个观点。我认为很多人仍然在使用LINQ，因为在C#wold还没有更新的技术。没错，没有什么东西会消亡，但事情确实会消失。