无法弄清楚基于类制作数组

Question

我想做的是从一个包含信息列表的类创建一个数组。

到目前为止我尝试过的是 - 首先，创建类：

Public Class PowerArray
    Public Name As String
    Public Action As String
    Public Cost As Integer
    Public Pool1 As String
    Public Pool2 As String
    Public Range As String
    Public Duration As String
    Public Tags As ArrayList = New ArrayList
    Public Desc As String
End Class

然后，定义一个使用 PowerArray 作为类型的新对象，包含在公共类中，以便可以在任何子类中调用它：

Public Class GVar
    Public Shared CharPowers(100) As PowerArray
    Public Shared PCount As Integer = 0
End Class

但是当我尝试写入该对象时，它不断抛出空引用异常。

例子：

尝试向 CharPowers(GVar.Pcount) 写入条目（其中 PCount 当前为 0，“txt.PowerName.Text”为任意字符串）：

GVar.CharPowers(GVar.PCount).Name = txtPowerName.Text

...抛出异常。无论我尝试写入哪个值，都会发生这种情况。

在使用该类型（不是数组，而只是一个简单的对象）在 sub 中定义新对象时，我没有遇到任何重大的挂断，所以我猜它是一个数组的对象投掷适合。我只是无法弄清楚如何或为什么。它显然存在，它是在启动时定义的。

Answer 1

GVar 中的数组是一个元素数组，类型为 PowerArray，值为 Nothing。您必须创建PowerArray 的实例并将其分配给数组元素，然后才能设置PowerArray 对象的字段。

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    Dim PA As New PowerArray
    GVar.CharPowers(GVar.PCount) = PA
    GVar.CharPowers(GVar.PCount).Name = TextBox1.Text
    MessageBox.Show(GVar.CharPowers(GVar.PCount).Name)
End Sub

您是否打算增加PCount？如果您使用List(Of PowerArray)，则无需跟踪您在数组中的位置。

编辑

Public Class PowerArray
    Public Property Name As String
    Public Property Action As String
    Public Property Cost As Integer
    Public Property Pool1 As String
    Public Property Pool2 As String
    Public Property Range As String
    Public Property Duration As String
    Public Property Tags As New List(Of Object)
    Public Property Desc As String
End Class

Public Class GVar
    Public Shared Property CharPowers As New List(Of PowerArray)
End Class

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    Dim PA As New PowerArray
    PA.Name = TextBox1.Text
    GVar.CharPowers.Add(PA)
    For Each item As PowerArray In GVar.CharPowers
        MessageBox.Show(item.Name)
    Next
End Sub

Answer 2

似乎我被一个答案绊倒了。特别是：

Public Class GVar
    Public Shared CharPowers(100) As PowerArray
    Public Shared PCount As Integer = 0
    Shared Sub New()
        For i = 0 To CharPowers.GetUpperBound(0)
            CharPowers(i) = New PowerArray
        Next
    End Sub
End Class