在调用方法之前，VB.Net检查以确定对象是否为null

Question

我遇到了以下问题，但无法识别错误，他指出这是“Me.sr.Read（Me.srcBT，0，CInt（Me.sr.Length））”的一部分。帮助

Public Function getFile(ByVal srcFile As String) As String
    Dim result As String

    If File.Exists(srcFile) Then
        Using sr As FileStream = New FileStream(srcFile, FileMode.Open, FileAccess.ReadWrite, FileShare.None)
            Dim srcBT(CInt(sr.Length) + 1) As Byte
            Me.sr.Read(Me.srcBT, 0, CInt(Me.sr.Length))
            Me.sr.Flush()
            Me.sr.Dispose()
            Me.sr.Close()
            result = Encoding.[Default].GetString(Me.srcBT)
            Return result
        End Using
    End If
    result = Nothing

    Return result
End Function