不同的字符串数组初始化之间的行为不同

Question

If I fill an array like

Return New String() {"A", "B"}

and return it in a property to display its elements into a combobox

Public Class Test
    Public ReadOnly Property TLTeams As String()
        Get
            'Return New String() {"A", "B"}
        End Get
    End Property
End Class

Public Class Form1
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Dim t As New Test
        For i As Integer = 0 To t.TLTeams.Length
            ComboBox1.Items.Add(t.TLTeams(i).ToString)
        Next i
    End Sub
End Class

It works fine. But if I change the initialization to

Public ReadOnly Property TLTeams As String()
    Get
        Dim a As String = "A"
        Dim b As String = "B"
        Dim ArS(1) As String
        Return ArS
    End Get
End Property

my combobox is empty (I dont get any error though). Could anyone explain that to me?

Answer 1

In the second example, if you want something to get back from the property then you need to fill the array.

Public ReadOnly Property TLTeams As String()
    Get
        Dim a As String = "A"
        Dim b As String = "B"
        Dim ArS(1) As String
        ArS(0) = a
        ArS(1) = b
        Return ArS
    End Get
End Property

However, given the context, returning a fixed set of constant strings, the first approach seems to be preferable. (Less code and the array size is calculated automatically).

If the context changes and you find yourself the need to return a variable number of strings then consider to use as a return type a List(Of String)