这个出错应该怎么处理？

guohq

    Public Function CurveLength(ByVal ID As ObjectId, ByRef Len As Double) As Boolean
        CurveLength = True
        Dim DB As Database = HostApplicationServices.WorkingDatabase

        Using Trans As Transaction = DB.TransactionManager.StartTransaction
            Try
                Dim Ent As Entity = Trans.GetObject(ID, OpenMode.ForRead)
                Dim Cur As Curve = Ent '此处如果不是线，会出错，用了TRY了，为什么不能跳到CATCH 处执行
                Len = Cur.GetDistanceAtParameter(Cur.EndParam)
            Catch ex As Exception
                CurveLength = False
                MsgBox("不正常")
            End Try
        End Using
    End Function

 

Dim Cur As Curve = Ent '此处如果不是线，会出错，用了TRY了，为什么不能跳到CATCH 处执行

雪山飞狐_lzh

If Ent Is Curve Then

guohq

谢谢！我想问的是为什么此处出错，不跳到CATCH处执行呢？