VB Web服务调用错误未设置对象引用

Question

嘿所有我想弄清楚为什么我会收到以下错误：

Object reference not set to an instance of an object.

代码第2行：

1.  Dim HTPCws As HTPCWS.ServiceVB
2.  Dim returned As String = HTPCws.DisplayMessageVB(what2send)

当我知道 what2send 确实有值发送....

Web服务代码是：

<WebMethod()> Public Function DisplayMessageVB(ByVal beingSent As String) As String
    _strfromws = beingSent
    Return "DONE"
End Function

我有什么可忘记的？

Answer 1

HTPCws尚未实例化。将代码更改为：

Dim HTPCws = New HTPCWS.ServiceVB()
Dim returned As String = HTPCws.DisplayMessageVB(what2send)

Dim HTPCws As HTPCWS.ServiceVB声明一个变量，但不为它指定一个对象。命名也有点令人困惑。更好：

Dim service = New HTPCWS.ServiceVB()
Dim returned As String = service.DisplayMessageVB(what2send)