VB.NET Queryable.Any方法代码示例

Dim numbers As New List(Of Integer)(New Integer() {1, 2})

' Determine if the list contains any elements.
Dim hasElements As Boolean = numbers.AsQueryable().Any()

MsgBox(String.Format("The list {0} empty.", _
    IIf(hasElements, "is not", "is")))

Structure Pet
    Public Name As String
    Public Age As Integer
End Structure

Structure Person
    Public LastName As String
    Public Pets() As Pet
End Structure

Sub AnyEx2()
    Dim people As New List(Of Person)(New Person() _
        {New Person With {.LastName = "Haas", _
                          .Pets = New Pet() {New Pet With {.Name = "Barley", .Age = 10}, _
                                             New Pet With {.Name = "Boots", .Age = 14}, _
                                             New Pet With {.Name = "Whiskers", .Age = 6}}}, _
          New Person With {.LastName = "Fakhouri", _
                           .Pets = New Pet() {New Pet With {.Name = "Snowball", .Age = 1}}}, _
          New Person With {.LastName = "Antebi", _
                           .Pets = New Pet() {}}, _
          New Person With {.LastName = "Philips", _
                           .Pets = New Pet() {New Pet With {.Name = "Sweetie", .Age = 2}, _
                                              New Pet With {.Name = "Rover", .Age = 13}}}})

    ' Determine which people have a non-empty Pet array.
    Dim names = From person In people _
                Where person.Pets.AsQueryable().Any() _
                Select person.LastName

    For Each name As String In names
        Console.WriteLine(name)
    Next

    ' This code produces the following output:
    '
    ' Haas
    ' Fakhouri
    ' Philips

End Sub

Structure Pet
    Dim Name As String
    Dim Age As Integer
    Dim Vaccinated As Boolean
End Structure

Shared Sub AnyEx3()
    ' Create an array of Pet objects.
    Dim pets() As Pet = _
        {New Pet With {.Name = "Barley", .Age = 8, .Vaccinated = True}, _
         New Pet With {.Name = "Boots", .Age = 4, .Vaccinated = False}, _
         New Pet With {.Name = "Whiskers", .Age = 1, .Vaccinated = False}}

    ' Determine whether any pets over age 1 are also unvaccinated.
    Dim unvaccinated As Boolean = _
    pets.AsQueryable().Any(Function(p) p.Age > 1 And p.Vaccinated = False)

    MsgBox(String.Format( _
        "There {0} unvaccinated animals over age one.", _
        IIf(unvaccinated, "are", "are not any") _
    ))
End Sub