How do a user select to display 1 out of two (or more) fields on a single label in xamarin

Quote:

I'm trying to use a single Label to display one of the two data fields alternately in Xamarin Forms. Only Label 1 Displaying the binding field (Contact_Name), while second Label which I am trying to use a variable "DisplayField" is not displaying either 'Contact_Address' or 'Contact_eMail'.

public class Contacts
{
    [PrimaryKey][AutoIncrement]
    public int Contact_ID { get; set; }
    public string Contact_Name { get; set; }
    public string Contact_Address { get; set; }
    public string Contact_eMail { get; set; }
}

 <StackLayout>
    <Button Text="Display Address" FontSize="Large" HorizontalOptions="Center" VerticalOptions="Fill" Clicked="Display_Address" />
    <Button Text="Display Email" FontSize="Large" HorizontalOptions="Center" VerticalOptions="Fill" Clicked="Display_eMail" />
    <Entry HorizontalOptions="FillAndExpand" Text="{Binding DisplayField}" />
    <ListView x:Name="listView" HasUnevenRows="True" >
        <ListView.ItemTemplate>
            <DataTemplate>
                <ViewCell >
                    <StackLayout Orientation="Vertical" VerticalOptions="CenterAndExpand" >
                        <Frame >
                            <StackLayout Orientation="Vertical" VerticalOptions="Center">
                                <Label Text="{Binding Contact_Name}" FontSize="Medium" LineBreakMode="WordWrap" />
                                <Label Text="{Binding DisplayField}" LineBreakMode="WordWrap" />
                            </StackLayout>
                        </Frame>
                    </StackLayout>
                </ViewCell>
            </DataTemplate>
        </ListView.ItemTemplate>
    </ListView>
</StackLayout>

public partial class FieldSwap : ContentPage
{
    readonly FieldViewModel _fieldViewModel;
    readonly SQLiteAsyncConnection _connection = DependencyService.Get<ISQLite>().GetConnection();
    public ObservableCollection<Contacts> CList { get; set; }
    public static string DisplayField { get; private set; }

    public static int caseSwitch { get; private set; }

    public FieldSwap()
    {
        InitializeComponent();
        _fieldViewModel = new FieldViewModel();
        _fieldViewModel.Field = "Contact_Address";
        
        this.BindingContext = _fieldViewModel;
    }

    public static void SelectField()
    {
        

        switch (caseSwitch)
        {
            case 1:
                DisplayField = "Contact_Address";
                break;

            case 2:
                DisplayField = "Contact_eMail";
                break;

            default:
                DisplayField = ("Contact_Address");
                break;
        }
    }

    private void Display_Address(object sender, EventArgs e)
    {
        caseSwitch = 1;
        SelectField();
        ReadData();
    }

    private void Display_eMail(object sender, EventArgs e)
    {
        caseSwitch = 2;
        SelectField();
        ReadData();
    }

    public void ReadData()
    {
        var list = _connection.Table<Contacts>().ToListAsync().Result;
        CList = new ObservableCollection<Contacts>(list);
        listView.ItemsSource = CList;
    }
}

public class FieldViewModel : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    String _displayField;

    public string DisplayField
    {
        set
        {
            if (!value.Equals(_displayField, StringComparison.Ordinal))
            {
                _displayField = value;
                OnPropertyChanged("DisplayField");
            }
        }
        get
        {
            return _displayField;
        }
    }

    void OnPropertyChanged([CallerMemberName] string propertyName = null)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}