wp7 - application.current as app Value can not be null

I put some properties in the App.xaml.cs file which I am using to store data and populate textboxes as I navigate through my application:

    public String appRXName { set; get; }
    public String appRXNumber { set; get; }

Originally I had a pivot control that called different p开发者_StackOverflow社区ages to gather data, but then I moved that pivot control item off to its own page that still calls other pages to collect data. Now when I run the application I get an error.

Basically it was working when I had it inside the original Pivot control. Once I moved it to a separate page (pivot page calles it) then I started to get this error:

System.ArgumentNullException was unhandled Message=Value can not be null. Parameter name: Text

No matter what page I hit always the second item in the list displays the error.

txtRxNotes.Text = (Application.Current as App).appDosageNotes;
txtQuantity.Text = (Application.Current as App).appQuantity.ToString();

I found something online about a RootVisual but I'm not sure if that is what I looking at or not. Does anyone have any ideas?

The ArgumentNullException is being thrown because the value that you are trying to set for the Text property is null, which you cannot do; the Text property is not a nullable type.

Without knowing how and when these application-level properties are being set it's difficult to provide a good explanation of why the behavior is different since your refactor, but you could either:

• Put a null check in the code that accesses these application-level properties.
• Initialise the application-level properties to string.Empty in the application constructor.