C＃WPF导航

Question

I am writing a WPF Appl. in C#. I got a MainWindow.xaml which contains an empty frame called MainFrame. I got four other pages called Welcome.xaml , Login.xaml , ObjectSelection.xaml and Exec.xaml . To navigate from MainWindow through the pages via the navigation buttons that are on the MainWindow , I simply can do this and call it on my buttons:

private void PageNav1(object sender, RoutedEventArgs e)
{
    MainFrame.Content = new Welcome();
}

I have buttons in that Welcome Page that need to bring you to another page, let's say to the Login.xaml . My approach was this:

private void SelectionExport(object sender, RoutedEventArgs e)
{
    MainWindow.MainFrame.Content = new Login();
}

But as usual I got an error: CS0120 An object reference is required for the non-static field, method, or property 'MainWindow.MainFrame' INTEGR8

Any idea is greatly appreciated.

Answer 1

You need to get a reference to the instance of the MainWindow class and access the Frame of this one:

private void SelectionExport(object sender, RoutedEventArgs e)
{
    MainWindow mainWindow = Application.Current.Windows.OfType<MainWindow>().FirstOrDefault();
    mainWindow.MainFrame.Content = new Login();
}

Answer 2

As the Documentation says

In order to use a non-static field, method, or property, you must first create an object instance.

For example,

public class MyClass 
{
    public void MyMethod() { }

    public static void MyStaticMethod() { }
}

MyClass.MyStaticMethod(); // Works
MyClass.MyMethod(); // CS0120

// You've got to do it like this

MyClass mc = new MyClass();
mc.MyMethod();