问VB.net中的LINQ语句

EN

Module Module1


    Public Class GradeBook
        Implements IComparable(Of GradeBook)

        Private nameValue As String
        Private scoreValue As Integer
        Public Sub New(ByVal n As String, ByVal s As Integer)
            nameValue = n
            scoreValue = s
        End Sub
        Public Property Name() As String
            Get
                Return nameValue
            End Get
            Set(ByVal value As String)
                nameValue = value
            End Set
        End Property

        Public Property Score() As Integer
            Get
                Return scoreValue
            End Get
            Set(ByVal value As Integer)
                scoreValue = value
            End Set
        End Property
        Public Sub displayGradeBook()
            Console.WriteLine("Name: " & Name & vbTab & "Score: " & Score)
        End Sub

        Public Function CompareTo(ByVal other As GradeBook) As Integer Implements System.IComparable(Of GradeBook).CompareTo
            '-1 = less than other; 0 = same as other; +1 = greater than other'
            If IsNothing(other) Then
                Return 1
            End If

            If Me.Score > other.Score Then
                Return 1
            End If

            If Me.Score < other.Score Then
                Return -1
            End If

            Return 0


        End Function

    End Class

    Sub Main()
        Dim g1 As New GradeBook("AAA", 70)
        Dim g2 As New GradeBook("BBB", 50)
        Dim g3 As New GradeBook("CCC", 100)
        Dim g4 As New GradeBook("DDD", 80)
        'add g1, g2, g3 and g4 in a array and display all student scores 
        Dim gradeBooks As GradeBook() = {g1, g2, g3, g4}
        display(gradeBooks, "Scores for all students: ")

        'create a LINQ which get all scores in ascending order and display them.
        Dim ascending =
            From value In gradeBooks
            Order By value Ascending
            Select value
        display(ascending, "Ascending Order")


        'create a LINQ which get all students who passed the exam
        Dim passed =
            From gradeBook In gradeBooks
            Where gradeBook.Score > 60
            Order By gradeBook
            Select gradeBook

        display(passed, "Students who passed: ")



        'display number of passed students, their names and scores  




    End Sub


    'display gradeBook's information 
    Private Sub display(ByVal gradeBooks As IEnumerable, ByVal header As String)
        Console.WriteLine(header)
        For Each g As GradeBook In gradeBooks
            g.displayGradeBook()
        Next
        Console.WriteLine()
        Console.ReadLine()

    End Sub

End Module

Dim ordered =
    From value In gradeBooks
    Order By value.Score
    Select value
display(ordered, "Ascending Order")

Dim passed =
    From gradeBook In gradeBooks
    Where gradeBook.Score > 60
    Order By gradeBook.Score
    Select gradeBook
display(passed, "Students who passed: ")