Solved

calling c# dll from VB.Net, setting a property of type list

Posted on 2014-01-23
2
458 Views
Last Modified: 2014-01-23
Hello.

I have a c# dll, and it has this class:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace CRPassThrough
{
    public class StringParams
    {
        public string ParamName { get; set; }
        public string ParamValue { get; set; }
    }
}

My plan is to use it like this:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using CrystalDecisions.CrystalReports.Engine;
using CrystalDecisions.Shared;
using System.Windows.Forms;

namespace CRPassThrough
{
    public class Main
    {
        public List<StringParams> SParams { get; set; }


        public bool Report()
        {
            try
            {
                if (SParams != null)
                {
                    foreach (StringParams SP in SParams)
                    {
                        -- do something with the parameters sent in --
                    }
                }

                return true;
            }
            catch (Exception ex)
            {
                return false;
            }
        }
    }
}



I am trying to call this dll from a VB.Net project:

    Private Sub bFull_Click(sender As Object, e As EventArgs) Handles bFull.Click

        Try
            Dim PT As New CRPassThrough.Main()

            Dim SParam As CRPassThrough.StringParams = New CRPassThrough.StringParams()
            SParam.ParamName = "Job_Number"
            SParam.ParamValue = Me.tJob.Text
            PT.SParams.Add(SParam)

        Catch ex As Exception
            Globals.WriteMessage(Me, "E", "Error Printing Report: " & ex.Message & vbCrLf, "frmPacklistReports,bFull_Click")
        End Try

    End Sub


At the line PT.SParams.Add(SParam), I get "Object Reference not set to an instance of an object.

PT.SParams is nothing, as the error would indicate.

However, when I try to create an instance of the object, e.g. with

Dim something as PT.SParams = new PT.SParams()

PT is not present (no intellisense, etc.)

What am I doing wrong, either in the dll or the VB project?



Thanks.
0
Comment
Question by:g_johnson
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
2 Comments
 
LVL 40

Accepted Solution

by:
Kyle Abrahams earned 500 total points
ID: 39803965
public List<StringParams> SParams { get; set; }

The list is never instantiated.

In the Main Constructor add the following:

SParams = new List<StringParams>();
0
 
LVL 4

Author Closing Comment

by:g_johnson
ID: 39804275
Thanks.
0

Featured Post

SharePoint Admin?

Enable Your Employees To Focus On The Core With Intuitive Onscreen Guidance That is With You At The Moment of Need.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Parsing a CSV file is a task that we are confronted with regularly, and although there are a vast number of means to do this, as a newbie, the field can be confusing and the tools can seem complex. A simple solution to parsing a customized CSV fi…
Real-time is more about the business, not the technology. In day-to-day life, to make real-time decisions like buying or investing, business needs the latest information(e.g. Gold Rate/Stock Rate). Unlike traditional days, you need not wait for a fe…
In this video, viewers will be given step by step instructions on adjusting mouse, pointer and cursor visibility in Microsoft Windows 10. The video seeks to educate those who are struggling with the new Windows 10 Graphical User Interface. Change Cu…
In this video, viewers are given an introduction to using the Windows 10 Snipping Tool, how to quickly locate it when it's needed and also how make it always available with a single click of a mouse button, by pinning it to the Desktop Task Bar. Int…

734 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question