当滚动到底部时，ListView自动添加更多内容

我已经ListView在我的xaml页面中创建了，并且正在从其cs页面上添加网格和按钮。当我在手机上运行此listview代码时，当我将其滚动到底部时，后面的代码将再次自动运行，并再次添加相同的代码listview。我希望此DataTemplate代码仅运行一个，当我滚动到底部时，listview它不应再次执行。不知道为什么它再次执行。

背后的代码

    public List<AmanoraSlotsClass> AmanoraSlotsClassesList { get; set; }
    public List<HadapsarSlots> HadapsarSlotClassesList { get; set; }
    

    string SelectedLocation = null;
    string SelectedDate = null;
    Dictionary<string, string> keyValuePairs = new Dictionary<string, string>();

    int OuterI = 0;
    int innerJ = 0;
    
    public ShowSlotsPage(string _Location, string _Date)
    {
        this.SelectedLocation = _Location;
        this.SelectedDate = _Date;
        
        SelectedDate = SelectedDate.Replace('/', '-');

        if (SelectedLocation == "Amanora Town Park")
        {
            AmanoraSlotsClassesList = new List<AmanoraSlotsClass>();
        }
        else if (SelectedLocation == "Hadapsar Malwadi")
        {
            HadapsarSlotClassesList = new List<HadapsarSlots>();
        }
        else
        {
            return;
        }

        FetchData(SelectedLocation, SelectedDate);

        InitializeComponent();
        BindingContext = this;


       //When i reach bottom of my listview this the control jumps to this and again adds same   elements.
        DataTemplate _dataTemplate = new DataTemplate(() =>
        {
           
            Grid _grid = new Grid();
            _grid.RowSpacing = 50;
            _grid.RowDefinitions.Add(new RowDefinition());
            _grid.ColumnDefinitions.Add(new ColumnDefinition());
            
            _grid.ColumnSpacing = 25;

            if (SelectedLocation == "Amanora Town Park")
            {
                OuterI = AmanoraSlotsClassesList[0].GetType().GetProperties().Count();
            }

            for (int i = 0; i < OuterI - 1; i++)
            {
                if (SelectedLocation == "Amanora Town Park")
                {
                    innerJ = AmanoraSlotsClassesList.Count();
                }
                for (int j = 0; j < innerJ; j++)
                {
                    Button _but = new Button();
                    _but.FontSize = 10;
                    _but.Scale = 1;
                    _but.HeightRequest = 70;
                    if (SelectedLocation == "Amanora Town Park")
                    {
                        _but.Text = AmanoraSlotsClassesList[j].S1;
                    }
                    keyValuePairs.Add(_but.Id.ToString(), $"S{i + 1}");

        //          ColorDtermination(_but);    //Changes color of button

                    Grid.SetRow(_but, j);
                    Grid.SetColumn(_but, i);
                    _grid.Children.Add(_but);
                }
            }

           var viewCell_ = new ViewCell
           {
                View = _grid
           };
            return viewCell_;

        });   ///*Till here code runs again when i scroll bottom of listview.*

         _listView.ItemTemplate = _dataTemplate;
        if(SelectedLocation == "Amanora Town Park")
        {
            _listView.ItemsSource = AmanoraSlotsClassesList;
        }
    }

1. XAML声明列表视图-列表视图的XAML declarion

2. CS页面代码截图**