Question

I am trying to create my hello world windows app in WPF.

What should I do to run this window?

Class1.xaml

<Window x:Class="Window1"
       xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
       xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
       Title="Window1" Height="300" Width="300">
        <Grid>    </Grid>
</Window>

App.xaml

<Application x:Class="App"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    StartupUri="Class1.xaml" >
    <Application.Resources>
    </Application.Resources>
</Application>

Program.cs

class Program
    {
        [STAThread]
        public static void Main()
        {
            new App().Run();
        }
    }

I have created a blank sln and added these three files. I have also added WindowsBase, PresentationBase, PresentationFramework refs.

But the App is not running.

What is the problem?

Answer 1

If you’re going to have a Main method, your App.xaml file will be ignored.

App.xaml is only used if you set its Build Action to be ApplicationDefinition. When you do this, you’ll notice you get a compiler error, as you’ll have two entry points into your program — so you’ll have to lose the Main method.

If you want to keep your Main method, you can. Don’t change the Build Action on App.xaml (actually, I think you can delete it), and do something like this:

[STAThread]
public static void Main()
{
    App app = new App();
    app.StartupUri = new System.Uri("/Project1;component/Class1.xaml", System.UriKind.Relative);                     
    app.Run();
}

Replace the /Project1 with your namespace.