NullReferenceException was unhandled

Question

I am Building a Webbrowser in C#: this is the code
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace Web_Browser
    public partial class Form1 : Form
        public Form1()
            InitializeComponent();
        private void goButton_Click(object sender, EventArgs e)
            webBrowser1.Navigate(new Uri(comboBox1.SelectedItem.ToString()));
        private void homeToolStripMenuItem_Click(object sender, EventArgs e)
            webBrowser1.GoHome();
        private void goBackToolStripMenuItem_Click(object sender, EventArgs e)
            webBrowser1.GoForward();
        private void goForwardToolStripMenuItem_Click(object sender, EventArgs e)
            webBrowser1.GoBack();
        private void Form1_Load(object sender, EventArgs e)
            comboBox1.SelectedText = "0";
            webBrowser1.GoHome();
the problem is: when I run it I get this error
"NullReferenceException was unhandeled"
at the bold line
can someone explane to me what I need to do??

Answer 1

Hi programming,
I have reproduced your code, and I was wondering what operation you made. If you debug your project and click the “goButton” after the form_load, it would appear the error message. It was becase your call the “comboBox1.SelectedItem” and “comboBox1.SelectedItem”
was never set. I think you could modify your Form1_Load like below:
private void Form0109_Load(object sender, EventArgs e)
//comboBox1.SelectedText = "0";
comboBox1.SelectedItem = comboBox1.Items[0];
webBrowser1.GoHome();
It would be helpful if you could share us how you get the error message.
Best Regards,
Edward
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