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Transfer values from one class to another using a list

I am facing a problem in my winforms app I am building in Visual Studio 2019. My app has 8 forms and I constructed a new class in which I want to save the name of the forms that users visited through a list and save them in a .txt file. I am providing you the pieces of code that I am trying to implement.
Code of one of 8 forms
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.SQLite;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Speech.Synthesis;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace Delfoi_Tourist_Guide
{
public partial class Welcome : Form
{
SQLiteConnection connection;
private SpeechSynthesizer speech = new SpeechSynthesizer();
public Welcome()
{
InitializeComponent();
User_History.HistList.Add(this.Name);
User_History.SaveHistory();
}
private void Welcome_Load(object sender, EventArgs e)
{
String conn = "Data Source=Delfoidb1.db;Version=3";
connection = new SQLiteConnection(conn);
connection.Open(); //or Create Database
}
private void Timer1_Tick(object sender, EventArgs e)
{
label1.Show();
label2.Show();
button1.Visible = true;
button2.Visible = true;
timer2.Enabled = true;
timer1.Enabled = false;
}
private void button1_Click(object sender, EventArgs e)
{
if (speech.State == SynthesizerState.Speaking)
{
speech.Pause();
}
Form2 form2 = new Form2();
form2.Show();
this.Visible = false;
}
private void button6_Click(object sender, EventArgs e)
{
Application.Exit();
}
private void timer2_Tick(object sender, EventArgs e)
{
speech.SelectVoice("Microsoft Stefanos");
speech.SpeakAsync(label2.Text);
timer2.Enabled = false;
}
private void button2_Click(object sender, EventArgs e)
{
if (speech.State == SynthesizerState.Speaking)
{
speech.Pause();
}
Form8 form8 = new Form8();
form8.Show();
this.Visible = false;
}
private void aboutToolStripMenuItem1_Click(object sender, EventArgs e)
{
MessageBox.Show("Developed by Ανδρέας Κρεούζος(ΜΠΠΛ20040) and Δημήτρης Γιογάκης(ΜΠΠΛ20008)");
}
private void helpToolStripMenuItem_Click(object sender, EventArgs e)
{
//Implement try - catch to avoid exception specifically for url error
try
{
Help.ShowHelp(this, "_tmphhp/Delfoi_Tourist_Guide_Help.chm", HelpNavigator.KeywordIndex, "Topic 1");
}
catch (Exception exception)
{
MessageBox.Show(exception.ToString());
}
}
private void aboutToolStripMenuItem_Click(object sender, EventArgs e)
{
if (speech.State == SynthesizerState.Speaking)
{
speech.Pause();
}
Welcome welcome = new Welcome();
welcome.Show();
this.Visible = false;
}
private void έξοδοςToolStripMenuItem_Click(object sender, EventArgs e)
{
Application.Exit();
}
}
}
Code of the separate class that saves the data as txt
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace Delfoi_Tourist_Guide
{
public static class User_History
{
public static List<string> HistList = new List<string>();
public static void SaveHistory()
{
SaveFileDialog saveFileDialog = new SaveFileDialog();
if (saveFileDialog.ShowDialog() == DialogResult.OK)
{
string path = saveFileDialog.FileName;
StreamWriter sw = new StreamWriter(path);
sw.WriteLine(HistList);
sw.Close();
}
}
}
}
My problem is that I can't transfer the data (placed on the InitializeComponent) from forms to my class. I am getting my txt file with nothing in it. My data is actually saved on my public static list but I can't transfer it next to the rest of my User_History class.
Any ideas on how to accomplish this???

You can try this SaveHistory() method
public static void SaveHistory()
{
SaveFileDialog saveFileDialog = new SaveFileDialog();
if (saveFileDialog.ShowDialog() == DialogResult.OK)
{
string path = saveFileDialog.FileName;
using (StreamWriter writer = new StreamWriter(path, false))
{
foreach (string history in HistList)
{
writer.WriteLine(history);
}
}
}
}

CefSharp Set Object reference for buttons C#?

WinForms:
I am new to Cefsharp and C# , just wrote a freeware 'Kid Safe Browser' in VS vb.net in visual basic , but IE11 is too limited .
I am getting "Object reference not set" for all Buttons . How to fix this ? For example:
How do I set an Object Reference for Chrome Load and Navigate Back Forward Refresh etc. ?
System.NullReferenceException
HResult=0x80004003
Message=Object reference not set to an instance of an object.
Source=CefSharpBrowser01
StackTrace:
at CefSharpBrowser01.SafeBrowser.GotoBtn_Click(Object sender, EventArgs e) in
C:\Users\vmars\source\repos\CefSharpBrowser01\Form1.cs:line 64
using CefSharp.WinForms;
using CefSharp.WinForms.Internals;
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;
using CefSharp;
using cef;
namespace CefSharpBrowser01
{
public partial class SafeBrowser : Form
{
public SafeBrowser()
{
InitializeComponent();
}
ChromiumWebBrowser chrome;
private void SafeBrowser_Load(object sender, EventArgs e)
{
CefSettings settings = new CefSettings();
//Initialize;
Cef.Initialize(settings);
AddressTxt.Text = "https://www.google.com";
chrome = new ChromiumWebBrowser(AddressTxt.Text);
this.Controls.Add(chrome);
chrome.Dock = DockStyle.Fill;
chrome.AddressChanged += Chrome_AddressChanged;
}
private void Chrome_AddressChanged(object sender, AddressChangedEventArgs e)
{
this.Invoke(new MethodInvoker(() =>
{
AddressTxt.Text = e.Address;
}));
}
private void BackBtn_Click(object sender, EventArgs e)
{
if (chrome.CanGoBack)
chrome.Back();
}
private void ForwardBtn_Click(object sender, EventArgs e)
{
if (chrome.CanGoForward)
chrome.Forward();
}
private void RefreshBtn_Click(object sender, EventArgs e)
{
chrome.Refresh();
}
private void GotoBtn_Click(object sender, EventArgs e)
{
chrome.Load(AddressTxt.Text);
}
}
}
Thanks for your Help...

Your problem really isn't anything to do with CefSharp, it's that you haven't created an instance of a class that you are trying to reference. Refactoring your code like I've suggested in the comments so the class is actually instantiated.
namespace CefSharpBrowser01
{
public partial class SafeBrowser : Form
{
public SafeBrowser()
{
InitializeComponent();
CefSettings settings = new CefSettings();
//Initialize;
Cef.Initialize(settings);
AddressTxt.Text = "https://www.google.com";
chrome = new ChromiumWebBrowser(AddressTxt.Text);
this.Controls.Add(chrome);
chrome.Dock = DockStyle.Fill;
chrome.AddressChanged += Chrome_AddressChanged;
}
ChromiumWebBrowser chrome;
private void Chrome_AddressChanged(object sender, AddressChangedEventArgs e)
{
this.Invoke(new MethodInvoker(() =>
{
AddressTxt.Text = e.Address;
}));
}
private void BackBtn_Click(object sender, EventArgs e)
{
if (chrome.CanGoBack)
chrome.Back();
}
private void ForwardBtn_Click(object sender, EventArgs e)
{
if (chrome.CanGoForward)
chrome.Forward();
}
private void RefreshBtn_Click(object sender, EventArgs e)
{
chrome.Refresh();
}
private void GotoBtn_Click(object sender, EventArgs e)
{
chrome.Load(AddressTxt.Text);
}
}
}

Open a new form by reading comboBox value

I'm not very versed in coding, let's say this is some kind of project I started without knowing anything about coding.
I have a Button which should read the selection in the comboBox and then open a specific form.
I've tried using following the switch (comboBox1.SelectedText)
While that didn't quite work, I tried another approach:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
namespace The_Liberion_Magnicite
{
public partial class Form1 : The_Liberion_Magnicite.Character
{
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
}
private void textBox1_TextChanged(object sender, EventArgs e)
{
}
private void label1_Click(object sender, EventArgs e)
{
}
private void button1_Click(object sender, EventArgs e)
{
comboBox1.SelectedText.ToString();
{ if (comboBox1.SelectedText.ToString() == "Shiroichi Kazami (PTS)")
{
this.Hide();
Shiro1 CShiro1 = new Shiro1();
CShiro1.Show();
}
else if (comboBox1.SelectedText.ToString() == "Shiroichi Kazami (ATS)")
{
this.Hide();
Shiro2 CShiro2 = new Shiro2();
CShiro2.Show();
}
else if (comboBox1.SelectedText.ToString() == "Akari Hondo")
{
this.Hide();
AkariHondo CAkari = new AkariHondo();
CAkari.Show();
}
else if (comboBox1.SelectedText.ToString() == "Aboa Sekihara")
{
this.Hide();
AobaSeki CAoba = new AobaSeki();
CAoba.Show();
}
}
}
}
}
I'm in some dire need for help ;)

Why do I cannot create a new Tab from another Form?

I want to call the NewTab() function from another form. But it doesn't work. I'm new to C# and Programming and need help.
Form1:
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;
using CefSharp;
using CefSharp.WinForms;
namespace Browser
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
ChromiumWebBrowser chrome;
private void Window_Load(object sender, EventArgs e)
{
CefSettings settings = new CefSettings();
Cef.Initialize(settings);
txtUrl.Text = "https://google.com";
chrome = new ChromiumWebBrowser(txtUrl.Text);
chrome.Parent = tabControl.SelectedTab;
chrome.Dock = DockStyle.Fill;
chrome.AddressChanged += Chrome_AddressChanged;
chrome.TitleChanged += Chrome_TitleChanged;
}
private void Chrome_AddressChanged(object sender, AddressChangedEventArgs e)
{
this.Invoke(new MethodInvoker(() =>
{
txtUrl.Text = e.Address;
}));
}
private void buttonRefresh_Click(object sender, EventArgs e)
{
ChromiumWebBrowser chrome = tabControl.SelectedTab.Controls[0] as ChromiumWebBrowser;
if (chrome != null)
{
chrome.Refresh();
}
}
private void buttonNavigate_Click(object sender, EventArgs e)
{
ChromiumWebBrowser chrome = tabControl.SelectedTab.Controls[0] as ChromiumWebBrowser;
if(chrome != null)
{
chrome.Load(txtUrl.Text);
}
}
private void buttonForward_Click(object sender, EventArgs e)
{
ChromiumWebBrowser chrome = tabControl.SelectedTab.Controls[0] as ChromiumWebBrowser;
if (chrome != null)
{
if (chrome.CanGoForward)
{
chrome.Forward();
}
}
}
private void buttonBack_Click(object sender, EventArgs e)
{
ChromiumWebBrowser chrome = tabControl.SelectedTab.Controls[0] as ChromiumWebBrowser;
if (chrome != null)
{
if(chrome.CanGoBack)
{
chrome.Back();
}
}
}
private void Window_FormClosing(object sender, FormClosingEventArgs e)
{
Cef.Shutdown();
}
public void btnNewTab_Click(object sender, EventArgs e)
{
NewTab("https://google.com");
}
public void NewTab(string url)
{
TabPage tab = new TabPage();
tab.Text = "New Tab";
tabControl.Controls.Add(tab);
tabControl.SelectTab(tabControl.TabCount - 1);
ChromiumWebBrowser chrome = new ChromiumWebBrowser(url);
chrome.Parent = tab;
chrome.Dock = DockStyle.Fill;
txtUrl.Text = url;
chrome.AddressChanged += Chrome_AddressChanged;
chrome.TitleChanged += Chrome_TitleChanged;
}
private void Chrome_TitleChanged(object sender, TitleChangedEventArgs e)
{
this.Invoke(new MethodInvoker(() =>
{
tabControl.SelectedTab.Text = e.Title;
}));
}
private void closeTabToolStripMenuItem_Click(object sender, EventArgs e)
{
tabControl.Controls.Remove(tabControl.SelectedTab);
}
private void openMultipleTabsToolStripMenuItem_Click(object sender, EventArgs e)
{
Form2 form2 = new Form2();
form2.Show();
}
}
}
Form2:
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 Browser
{
public partial class Form2 : Form
{
public Form2()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
Form1 form1 = new Form1();
form1.NewTab("https://google.com");
}
}
}
I try to make a Webbrowser with special features. I use CefSharp for this. Sorry for the ugly Code I'm new to C# and Programming. Got most of this from a Youtube tutorial. I'm trying to make another window that you can open with a menustrip that lets you open multiple tabs at once. But for now, I don't even get one new Tab opened. It could be nice if you help me with this.

You create a new instance of Form1 but you don't show it.
Try this:
private void button1_Click(object sender, EventArgs e)
{
Form1 form = new Form1();
form.NewTab("https://google.com");
form.Show();
}

l versC# multithread issue

I cannot get the ui thread to update the ui while the file copy thread is running. My end goal is to have the animation continue to rotate until the large file copy finally completes to let the user know that the program is not frozen. It's a very simple server to server file copy program.
Can someone tell me what I'm doing wrong?
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;
using System.Threading;
using System.IO;
using System.Threading.Tasks;
namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void ResetProgress()
{
lblStep1.Image = null;
}
private void SetupProgress()
{
lblStep1.Image = global::animation1.Properties.Resources.animation;
}
private void fileCopy()
{
File.Copy("large file source", "large file destination", true);
}
private void Form1_Load(object sender, EventArgs e)
{
lblStep1.Image = global::animation1.Properties.Resources.animation;
}
private async void button1_Click(object sender, EventArgs e)
{
SetupProgress();
await Task.Run(() => fileCopy());
ResetProgress();
}
private void btnStop_Click(object sender, EventArgs e)
{
// unhandled currently
}
}
}
* Original version *
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;
using System.Threading;
using System.IO;
using System.Threading.Tasks;
namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
private Thread workItemsProducerThread;
private Thread workItemsCopyThread;
public Form1()
{
InitializeComponent();
}
private void ResetProgress()
{
lblStep1.Image = null;
}
private void SetupProgress()
{
this.BeginInvoke((MethodInvoker)delegate ()
{
lblStep1.Image = global::animation1.Properties.Resources.animation;
});
}
private void fileCopy()
{
File.Copy("Large file source", "Large file destination", true);
this.BeginInvoke((MethodInvoker)delegate ()
{
MessageBox.Show("Done");
});
}
private void Form1_Load(object sender, EventArgs e)
{
lblStep1.Image = global::animation1.Properties.Resources.animation;
}
private void btnStart_Click(object sender, EventArgs e)
{
this.workItemsProducerThread = new Thread(new ThreadStart(this.SetupProgress));
this.workItemsProducerThread.IsBackground = true;
this.workItemsProducerThread.Start();
this.SetupProgress();
this.workItemsCopyThread = new Thread(new ThreadStart(this.fileCopy));
this.workItemsCopyThread.IsBackground = true;
this.workItemsCopyThread.Start();
while (workItemsCopyThread.IsAlive)
{
Thread.Sleep(1000); // wait
}
MessageBox.Show("Done");
}
private void btnStop_Click(object sender, EventArgs e)
{
if (this.workItemsProducerThread != null)
{
this.workItemsProducerThread.Abort();
lblStep1.Image = global::animation1.Properties.Resources.animation;
}
}
private void btnTest_Click(object sender, EventArgs e)
{
fileCopy();
}
}
}

Don’t sleep in your click handler. That freezes the UI thread. Just let the clock handler exit. In your file copy thread, when the copy is don’t. Use Invoke(or BeginInvoke) to cause the done messagebox to pop up on the UI thread.

Try this oldy style
private void SetupProgress()
{
Invoke((MethodInvoker) delegate
{
lblStep1.Image = global::animation1.Properties.Resources.animation;
});
}
private Thread TDoSomeWork()
{
var t = new Thread(() => DoSomeWork());
t.Start();
return t;
}
TDoSomeWork();