Static Variable bound to textblock not updated

Question

I'm using a textblock with a binding to a variable in a static class. If the variable is set initially within the class, the text is updated. But when the variable changes within a method the bound textblock text does not change.

I set the value initialy to "initial text" and afterwards, I try to change it within a method. But the text never changes, even if i see it changes in the debugger.

I added a textblock with a binding to a static variable:

<TextBlock Text="{x:Static local:InfoBanner.InfoBannerText}"/>

In the code, I implemented the following class:

public static class InfoBanner
{
    static InfoBanner()
    {
        infoBannerText = "initial text";
    }

    public static void showMessage(Window window)
    {
        infoBannerText = "changed text";
        Storyboard sb = window.FindResource("storyInfoBanner") as Storyboard;
        sb.Begin();
    }

    public static string infoBannerText;

    public static String InfoBannerText
    {
        get { return infoBannerText; }
        set {
            infoBannerText = value;
            StaticPropertyChanged?.Invoke(null, FilterStringPropertyEventArgs);
        }
    }

    public static readonly PropertyChangedEventArgs FilterStringPropertyEventArgs = new PropertyChangedEventArgs(nameof(InfoBannerText));
        public static event PropertyChangedEventHandler StaticPropertyChanged;

}

What I expected was, that the text updates every time I call the method showMessage. But the text keeps the value "initial text"

Does anyone has an idea what I'm doing wrong? Best regrads hafisch

Answer 1

Besides that you must update the property - not its backing field - by calling

InfoBannerText = "changed text";

you have to use a Binding for the Text property, instead of just an assignment:

Text="{Binding Path=(local:InfoBanner.InfoBannerText)}"

Answer 2

Thanks for your comments:

I adjusted all your suggestions. But still it's not updated:

public static class InfoBanner
{
    static InfoBanner()
    {
        InfoBannerText = "Initial Text";
    }

    public static void showMessage(Window window)
    {
        InfoBannerText = "Changed text";
        Storyboard sb = window.FindResource("storyInfoBanner") as Storyboard;
        sb.Begin();

    }

    public static string infoBannerText;

    public static String InfoBannerText
    {
        get { return infoBannerText; }
        set {
            infoBannerText = value;
            StaticPropertyChanged?.Invoke(null, new PropertyChangedEventArgs(nameof(InfoBannerText)));
        }
    }

    public static event PropertyChangedEventHandler StaticPropertyChanged;

}

Thanks for your answers.