I have been working on c# for about 3 hours and Visual Studio does not show the UI while running the application. It shows the UI in designer but after compiling and running, it just goes blank.
Two things to test:
In the code file Program.cs, you will find something like this:
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Form1());
}
Does the name of the form in the line Application.Run match the name of your form?
Your form's code behind (Form1.cs) should have a constructor looking like this
public Form1() // Where the name of the constructor must match the one of the form class.
{
InitializeComponent();
// Your code goes here (if any) ...
}
Does it have this constructor? If yes, does it call InitializeComponent?
InitializeComponent is very important, because it creates the controls and configures the form. You may have replaced it with your own code. Always call it before your initialization code.
I guess the entry point if your application is wrong. Check the solution properties (right click on your application/solution in the solution explorer -> properties ) for the correct entry point.
It looks like you have more than one form.
Go to the Program.cs file and verify if the class of the form is in Application.Run() method
static class Program
{
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main ()
{
Application.EnableVisualStyles ();
Application.SetCompatibleTextRenderingDefault (false);
Application.Run (new urltetx());
}
}
Related
I have a completely functioning application that I have converted to a Dll.
I need to be able to run that application (now dll) out of an exe . Ive added the dll as a reference to the new exe and have tried to just instantiate a frmMain object from the namespace used in the dll and show it like I would in any other application.
However, I get a bunch of null reference exceptions in several of the references that I had in the exe that I converted to a dll.
I've also tried the solution here Launch Dll using C# program
and tried jumping to the Program.cs Main() function at which point I get a "SetCompatibleTextRenderingDefault must be called before the first IWin32Window object is created in the application." error.
Here is the dll's program.cs
namespace VTRS
{
class Program
{
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new frmMain());
}
//had to add this because exe can't find Main
public void invokeMain()
{
Main();
}
//you have to have a constructor for the exe to instantiate this class
public Program()
{
}
}
}
and here is the new applications code
private void button1_Click(object sender, EventArgs e)
{
try
{
System.Reflection.Assembly dll1 = System.Reflection.Assembly.LoadFile(Application.StartupPath + "\\VTRSTCACodeMaintenance.dll");
if (dll1 != null)
{
object obj = dll1.CreateInstance("VTRS.Program");
if (obj != null)
{
System.Reflection.MethodInfo mi = obj.GetType().GetMethod("invokeMain");
mi.Invoke(obj, new object[0]);
}
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}
Can anyone explain to me why this doesn't work or point me in the right direction? I'm super confused and am not doing this by choice (I'm being told to by the boss)
You do not need reflection, nor do you need to execute the Main() method of your original .exe file (indeed, you should probably just remove it, if that project is intended to just be a plain DLL).
You don't need reflection because, once you've added the assembly as a reference in your new project, all of the public types and members are accessibly in your new project. Just make sure you've declared frmMain as public (this is the default in Visual Studio, so it may already be public). Then instead of all that reflection rigmarole, all you need to do is what you'd normally do to show a form:
frmMain form = new frmMain();
form.Show();
or even just:
new frmMain().Show();
You don't need to execute the Main() method, because all it does is work that your new project already does:
The [STAThread] sets the entry point thread (which becomes the main UI thread) to the STA apartment model. But since your new project is also (it seems) a Winforms program, you already have an entry point and a main UI thread that has been correctly configured. It's this thread in which the Click event for button1 is raised, and so you are executing in that thread when the button1_Click() method is called.
Likewise, the calls to set the visual styles and text rendering. You don't need to call these again, because your new project called them when it started.
Finally, the call to Application.Run(new frmMain()). This call has three effects: it creates an instance of frmMain() (which you can do yourself as I noted above), it then passes that instance to the Application.Run() method so that method can call the Show() method on the form (again, you can do that yourself), and then the Run() method sits in a loop dispatching window messages. You also don't need to do that because, again, you are already in a Winforms program, which has already called Application.Run(), and is already dispatching window messages (which is how the Click event got raised in the first place).
So, stop trying to invoke the Main() method, just make sure the form class you want to use is public so it's visible from projects that reference the assembly, and just create and show the frmMain object the way you would if it were declared in the same project.
I think it's because of the access modifier of the class program just change it to public.
also if you don't load a changeable dll (dynamic) why you don't just reference it to the project as you would normally do with other dll's and call the main from the program class (you still need program class to be public)
In Solution Explorer, in your project view right click on References --> Add New Reference --> Browse --> Find VTRSTCACodeMaintenance.dll(it should be in your \bin\debug folder) --> double click it --> click Ok.
That is basically.
I'm new to C# (switching from Java) and i'm having a bit of trouble understanding GUI in C#
Ill just paste the Code i have and let that explain the most part.
Main Class:
Frame frame;
keepRunning = true;
public GraphicsComponent()
{
frame = new Frame();
frame.Show();
}
public void run()
{
while (keepRunning)
{
Console.WriteLine("Running");
}
}
public static void Main()
{
GraphicsComponent gameComponent = new GraphicsComponent();
gameComponent.run();
}
using the frame.Show() method, it appears and disappears for a quick moment. but the "running" loop is run.
The other way i have seen is another method called ShowDialoge(), that one keeps the window open but blocks the rest of the code from running until it is closed.
The way i want to use it is basically how GUIs work in Java. Where i can reference an object (and it's components) as needed in the rest of my code.
Thanks heaps!
Edit: There is alot of confusion, so here is my Frame class:
public partial class Frame : Form
{
public Frame()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
}
}
A normal way to kick off a winforms application is by file->new winforms project. WHen you do this you get "Program.cs", which contains your Main method - the entry point into your application. From there you have code like this:
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new ConfigForm());
}
In this example I kick off a new "ConfigForm"" that is a Form, and contains in it's ctor some code that looks like this:
public ConfigForm()
{
InitializeComponent();
// Other init work here
}
I create the form by right-clicking in the project and adding a new form.
You might want to look into the Application.Run method, see here. You can specify a "Main Form" which is going to be the main form that runs for the duration of the application, and when closed ends the application, or you can specify other options if you want. Perhaps the simplest solution is to start a main form, and since the form is live for the duration of the application, you can kick off other long-running code inside that form. If it's code that you want to be executing all the time performing some sort of background operation then you might want to fire it off in it's own thread. However, threading is hard so if you're new to c# / .net I'd try to stay away from threading unless you need it.
Class A has a Form1 (subclass of System.Windows.Forms.Form) member.
class A {
Form1 form;
public A()
{
form = new Form1();
form.Show();
}
}
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
A a = new A();
Application.Run();
}
The problem is I do not know how to exit the program. I have tried Application.Exit() when handling the Form.Closed event or call A.Dispose(), but the Windows Task Manager still lists the process of my program.
How do I finish this program?
Application.Run has 3 overloads. You are using this one with no arguments.
Windows runs your program in a message loop, but it doesn't care about your form.
So if you close your form it doesn't matter; the program will still run.
The second overload is what everyone uses, Application.Run(Form). This one runs a Windows message loop over your form, so when you click close on the window, the application closes.
Your code should be:
class A {
Form1 form;
public A()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
form = new Form1();
form.Show();
Application.Run(form);
}
}
[STAThread]
static void Main()
{
A a = new A();
}
Following Microsoft you should use this:
Application.Run(a.Form);
Because MSDN states that
Most Windows Forms developers will not need to use this version of the method. You should use the Run(Form) overload to start an application with a main form, so that the application terminates when the main form is closed.
I think you have a mixup there. Check the documentation for Application.Exit.
There you will see that Exit will raise the Closed event for you, and calling Exit there might cause an infinite loop (which might be causing your problem, that the application is still visible).
Try this:
Environment.Exit(1);
I'm working with a C# project using System.Windows.Form to create the GUI, I have two forms within the VS project( MainForm and InitialPrompt). I've never used Forms before and Google hasn't been of much help.
Intended action:
InitialPrompt Load
Click Button on InitialPrompt
Load MainForm
However, since MainForm was created first there is some property/method that allows it to load first and the InitialPrompt does not load at all. How to I make MainForm the secondary form and InitialPrompt the primary?
Thanks in advance.
namespace WindowsFormsApplication1
{
static class Program
{
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Form1());
}
}
}
You can change the above code to read
Application.Run(new Form2()); // or whatever the name of the second form is.
This is found in your Program.cs file.
Look for the Program.cs file inside your project. Inside you will see something like this:
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new MainForm());
}
Just change new MainForm() to new InitialPrompt(). This will make InitialPrompt the main form.
Like any other .Net project it is the static void Main() method in a class defined in your project. Because of this, only one static void Main() method is allowed in a project.
NOTE: this static Main method must be defined as void return type, and it can either take no arguments, or it can be defined to take an array of strings to be passed as command line arguments.
Can you exit an application before the constructor is finished and the main form is loaded?
At startup, I have a loading screen that displays before the main form is loaded. The loading screen is displayed from the constructor before the constructor has finished.
I do something similar with an exit screen by using a variable between the main form and the exit screen. I have an application exit in the main form if the exit screen returns true.
Finally, should all the thread/class/loading/program setup be done in the main constructor or am I doing it wrong?
Update:
I mean after the program.cs and in the static main
namespace app
{
public partial class app1 : Form
{
public app1()
{
InitializeComponent();
// open loading screen
// initialize vars
// create objects
}
// form opens when app1() finishes
Is app1() the right place to initialize everything?
If I try to send a "close" message back from the loading screen before app1() is finished, it doesn't work - the process still runs even though nothing is open.
I've found that if I try to kill my application from the main form constructor when I still have the splash screen showing on a different thread (which looks similar to what you are doing), that Application.Exit() does not work, but Environment.Exit(-1) does.
try this,
public partial class MyForm : Form
{
public MyForm()
{
if (MyFunc())
{
this.Shown += new EventHandler(MyForm_CloseOnStart);
}
}
private void MyForm_CloseOnStart(object sender, EventArgs e)
{
this.Close();
}
}
it will work well...
Which main constructor of which class?
Are you talking about the static method Main that has a default location in the Program class?
You use that method to do initialization that needs to occur before you open any windows on screen.
Obviously, if you need to use a loading screen, you will probably want to move some code somewhere else, as you need a message loop around forms, and the message loop will block until your form closes.
If you return from the Main method before you open any form, then no form will be shown obviously.
Having said all that, I feel your question is a bit vague and I'm pretty sure I didn't understand exactly what it is that you're asking.
First and foremost, Main is not a constructor, it's just a static method.
When main thread ends:
background threads are "killed/abandoned"
foreground threads (the default when creating threads) are waited till they finish.
you can break constructor only via throwing an exception. To do that surreptitiously, throw you own specific exception.
class ConstructorAbortedException : Exception { }
class Foo
{
public Foo()
{
if(goesWrong)
{
throw new ConstructorAbortedException();
}
}
}
void Bar()
{
try
{
Foo f = new Foo();
}
catch(ConstructorAbortedException)
{
//..
}
}
As jontsnz answered, the code with
Environment.Exit(-1)
works fine in the constructor, but this causes the application to throw an "Application Hang" event, which can be seen as an error in the Windows Event Viewer. Using
Environment.Exit(0)
exits without registering an error though, so I prefer that one.