删除文本文件中重复行（vb.net）

    ''' <summary>
    ''' 读文本文件，删除重复行并输出：
    ''' </summary>
    ''' <returns></returns>
    ''' <remarks></remarks>
    Private Function delDuplicate() As ArrayList
        Dim arrContent(), strFileWritePath As String
        Dim sr As StreamReader
        Dim sw As StreamWriter
        Dim list As New ArrayList()
        Dim strFileReadPath As String = mString.mTrim(txtFilePath.Text)

        If File.Exists(strFileReadPath) Then
            sr = New StreamReader(strFileReadPath, System.Text.Encoding.Default)
            arrContent = sr.ReadToEnd.Split(vbCrLf)
            sr.Close()
            If arrContent.Count > 0 Then
                For i As Integer = 0 To arrContent.Count - 1
                    Dim blIsSingle As Boolean = True
                    For j As Integer = 0 To list.Count - 1
                        If list.Count > 0 AndAlso String.Compare(mString.mTrim(list(j).ToString), mString.mTrim(arrContent(i).ToString)) = 0 Then
                            blIsSingle = False
                            Exit For
                        End If
                    Next
                    If blIsSingle Then
                        list.Add(arrContent(i))
                    End If
                Next
                strFileWritePath = strFileReadPath.Remove(strFileReadPath.IndexOf(".")) & "_去重.txt"