c# - How to access a variable from outside its class in a method in some other class?

Question

I am a beginner in c# programming and I am developing windows phone application after reading some tutorials.

My idea is when the user clicks a button in a windows page, some other button in other windows phone page must change color from red to green.

Pardon me if I am too Basic.

This I have defined in a page named "IndexPage.xaml"

        <Button x:Name="One_green"
            Content="1"             
            Background="Green"
            Click="One_Click"
         />

        <Button x:Name="One_red"
            Content="1"             
            Background="Red"
            Click="One_Click"                       
         />

Now I see red color button in my window as green button is hidden in the back.

Now, the following code is from another windows phone page "1.xaml"

        <Button Content="GO" Click="Button_Click"/>

Now when the user clicks the "GO" Button I want the button to change to red to green in "IndexPage.xaml". So I tried a code something like this in "1.xaml.cs"

        private void Button_Click(object sender, RoutedEventArgs e)
        {  
        One_red.Visibility = Visibility.Collapsed;
        One_green.Visibility = Visibility.Visible;
        }

But I am not able to access the "One_red" or "One_green" button in the above code. Please shed me directions.

Also I want that code to execute only once. (i.e.) when the IndexPage.xaml loads again I want that button to be green always.

Thank you very much in advance.

Please tell me if some other details are required.

Answer 1

You could define a public or internal static variable inside the "Index.xaml" class specifying what button will show on load until otherwise specified. This variable could be accessed outside the class, and possibly even outside the project depending on the modifier chosen. The constructor of the "Index.xaml" class could have code to reset it to the default to ensure it only happens on the next creation of the page. If you aren't creating a new page everytime, you would have to put the default resetters in a method called when you want to bring it to foreground.