Question

I’m trying to make a multiWindowsForm.

Just to try how it is working I started with a a simple form that I added a button to. When clicking on it, another window should pop up. But I can’t get it to work. It crashes with error:

Object reference not set to an instance of an object!

I used Project → Add → Windows form and named it Mupp.cs

Here’s my code for Form1.cs :

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace MultiForm
{
    public partial class tryout : Form
    {
        public tryout()
        {
            InitializeComponent();
        }

        Mupp theMupp;

        private void Form1_Load(object sender, EventArgs e)
        {
            theMupp = new Mupp();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            theMupp.Show();
        }
    }
}

What can I have missed out on?

Answer 1

It looks like the load event is not firing and thus not initilising your object. Make sure that the load event is hooked up.

Alternatively, initialise in the click event.

 private void button1_Click(object sender, EventArgs e)
 {
     using (Mupp theMupp = new Mupp())
     {
         theMupp.ShowDialog();
     }
 }

I hope this helps.