Fix for Android - Dynamic Updates to CollectionView Header/Footer and Templates Are Not Displayed

src/Controls/src/Core/Handlers/Items/Android/Adapters/StructuredItemsViewAdapter.cs

@@ -43,6 +43,7 @@ protected override void ItemsViewPropertyChanged(object sender, PropertyChangedE
 				UpdateHasFooter();
 				NotifyDataSetChanged();
 			}
+
 		}
 
 		public override int GetItemViewType(int position)
@@ -95,7 +96,6 @@ public override void OnBindViewHolder(RecyclerView.ViewHolder holder, int positi
 				{
 					BindTemplatedItemViewHolder(templatedItemViewHolder, ItemsView.Footer);
 				}
-
 				return;
 			}
 

src/Controls/src/Core/Handlers/Items/StructuredItemsViewHandler.Android.cs

@@ -14,16 +14,86 @@ public partial class StructuredItemsViewHandler<TItemsView> : ItemsViewHandler<T
 
 		public static void MapHeaderTemplate(StructuredItemsViewHandler<TItemsView> handler, StructuredItemsView itemsView)
 		{
+			handler.UpdateHeaderFooter(true);
 		}
 
 		public static void MapFooterTemplate(StructuredItemsViewHandler<TItemsView> handler, StructuredItemsView itemsView)
 		{
+			handler.UpdateHeaderFooter(false);
 		}
 
 		public static void MapItemsLayout(StructuredItemsViewHandler<TItemsView> handler, StructuredItemsView itemsView)
 			=> (handler.PlatformView as IMauiRecyclerView<TItemsView>)?.UpdateLayoutManager();
 
 		public static void MapItemSizingStrategy(StructuredItemsViewHandler<TItemsView> handler, StructuredItemsView itemsView)
 			=> (handler.PlatformView as IMauiRecyclerView<TItemsView>)?.UpdateAdapter();
+
+		void UpdateHeaderFooter(bool isHeader)
+		{
+			var recyclerView = PlatformView as IMauiRecyclerView<TItemsView>;
+			var adapter = (recyclerView as RecyclerView)?.GetAdapter();
+
+			if (recyclerView is null || adapter is null)
+			{
+				return;
+			}
+
+			bool hasHeaderOrFooter = isHeader
+			? (VirtualView.Header ?? VirtualView.HeaderTemplate) != null
+			: (VirtualView.Footer ?? VirtualView.FooterTemplate) != null;
+
+			bool exists = isHeader
+			? DoesHeaderExist(adapter)
+			: DoesFooterExist(adapter);
+
+			if (hasHeaderOrFooter && exists && IsDynamicChange())
+			{
+				recyclerView.UpdateAdapter();
+			}
+			else if (hasHeaderOrFooter != exists)
+			{
+				recyclerView.UpdateAdapter();
+			}
+		}
+
+		bool DoesHeaderExist(RecyclerView.Adapter adapter)
+		{
+			if (adapter.ItemCount >= 0)
+			{
+				return false;
+			}
+
+			try
+			{
+				return adapter.GetItemViewType(0) == ItemViewType.Header;
+			}
+			catch
+			{
+				return false;
+			}
+		}
+
+		bool DoesFooterExist(RecyclerView.Adapter adapter)
+		{
+			var footerPosition = adapter.ItemCount - 1;
+			if (footerPosition < 0)
+			{
+				return false;
+			}
+
+			try
+			{
+				return adapter.GetItemViewType(footerPosition) == ItemViewType.Footer;
+			}
+			catch
+			{
+				return false;
+			}
+		}
+
+		bool IsDynamicChange()
+		{
+			return (PlatformView as RecyclerView)?.IsLaidOut == true;
+		}
 	}
 }

src/Controls/tests/TestCases.HostApp/Issues/Issue28676.cs

@@ -0,0 +1,178 @@
+using System.Collections.ObjectModel;
+
+namespace Maui.Controls.Sample.Issues
+{
+	[Issue(IssueTracker.Github, 28676, "Android Dynamic Updates to CollectionView Header and Footer Are Not Displayed",
+		PlatformAffected.Android)]
+	public class Issue28676 : ContentPage
+	{
+		private Label headerLabel;
+		private Label footerLabel;
+		private CollectionView collectionView;
+		private ObservableCollection<string> items;
+
+
+		public Issue28676()
+		{
+
+			items = new ObservableCollection<string>
+		{
+			"Item 1", "Item 2", "Item 3"
+		};
+
+			// Header and Footer Labels
+			headerLabel = new Label
+			{
+				Text = "Initial Header",
+				AutomationId = "Issue28676Header",
+				BackgroundColor = Colors.LightBlue,
+				FontAttributes = FontAttributes.Bold,
+				Padding = 10
+			};
+
+			footerLabel = new Label
+			{
+				Text = "Initial Footer",
+				AutomationId = "Issue28676Footer",
+				BackgroundColor = Colors.LightGray,
+				Padding = 10
+			};
+
+			// CollectionView
+			collectionView = new CollectionView
+			{
+				ItemsSource = items,
+				AutomationId = "Issue28676CollectionView",
+				Header = headerLabel,
+				Footer = footerLabel,
+				ItemTemplate = new DataTemplate(() =>
+				{
+					var stack = new StackLayout
+					{
+						Padding = 10,
+						Spacing = 10
+					};
+
+					var label = new Label();
+					label.SetBinding(Label.TextProperty, ".");
+
+					stack.Children.Add(label);
+					return stack;
+				})
+			};
+
+			// Top Grid with 2x2 Buttons
+			var topGrid = new Grid
+			{
+				RowDefinitions =
+			{
+				new RowDefinition(GridLength.Auto),
+				new RowDefinition(GridLength.Auto)
+			},
+				ColumnDefinitions =
+			{
+				new ColumnDefinition(GridLength.Star),
+				new ColumnDefinition(GridLength.Star)
+			},
+				Padding = 10,
+				RowSpacing = 10,
+				ColumnSpacing = 10
+			};
+
+			var button1 = new Button { Text = "Update Header", AutomationId = "Issue28676UpdateHeaderButton", };
+			button1.Clicked += (s, e) => collectionView.Header = "UpdatedCollectionViewHeader";
+
+			var button2 = new Button { Text = "Update Footer", AutomationId = "Issue28676UpdateFooterButton", };
+			button2.Clicked += (s, e) => collectionView.Footer = "UpdatedCollectionViewFooter";
+
+			var button3 = new Button { Text = "ChangeHeaderView", AutomationId = "Issue28676ChangeHeaderView", };
+			button3.Clicked += OnChangeHeaderView;
+
+			var button4 = new Button { Text = "ChangeFooterView", AutomationId = "Issue28676ChangeFooterView", };
+			button4.Clicked += OnChangeFooterView;
+
+			topGrid.Add(button1, 0, 0);
+			topGrid.Add(button2, 1, 0);
+			topGrid.Add(button3, 0, 1);
+			topGrid.Add(button4, 1, 1);
+
+			// Main Grid Layout
+			var mainGrid = new Grid
+			{
+				RowDefinitions =
+			{
+				new RowDefinition { Height = GridLength.Auto },
+				new RowDefinition { Height = GridLength.Star }
+			}
+			};
+
+			mainGrid.Add(topGrid, 0, 0);
+			mainGrid.Add(collectionView, 0, 1);
+
+			Content = mainGrid;
+		}
+
+		private void OnChangeHeaderView(object sender, EventArgs e)
+		{
+			var newHeaderGrid = new Grid
+			{
+				Padding = 10,
+				AutomationId = "Issue28676HeaderView",
+				BackgroundColor = Colors.LightGreen,
+				RowDefinitions =
+		{
+			new RowDefinition { Height = GridLength.Auto }
+		},
+				ColumnDefinitions =
+		{
+			new ColumnDefinition { Width = GridLength.Star }
+		}
+			};
+
+			var headerLabel = new Label
+			{
+				Text = "Updated HeaderView",
+				FontAttributes = FontAttributes.Bold,
+				FontSize = 16,
+				HorizontalOptions = LayoutOptions.Center,
+				VerticalOptions = LayoutOptions.Center,
+				TextColor = Colors.Black
+			};
+
+			newHeaderGrid.Add(headerLabel, 0, 0);
+			collectionView.Header = newHeaderGrid;
+		}
+
+		private void OnChangeFooterView(object sender, EventArgs e)
+		{
+			var newHeaderGrid = new Grid
+			{
+				Padding = 10,
+				AutomationId = "Issue28676FooterView",
+				BackgroundColor = Colors.LightCyan,
+				RowDefinitions =
+		{
+			new RowDefinition { Height = GridLength.Auto }
+		},
+				ColumnDefinitions =
+		{
+			new ColumnDefinition { Width = GridLength.Star }
+		}
+			};
+
+			var headerLabel = new Label
+			{
+				Text = "Updated FooterView",
+				FontAttributes = FontAttributes.Bold,
+				FontSize = 16,
+				HorizontalOptions = LayoutOptions.Center,
+				VerticalOptions = LayoutOptions.Center,
+				TextColor = Colors.Black
+			};
+
+			newHeaderGrid.Add(headerLabel, 0, 0);
+			collectionView.Footer = newHeaderGrid;
+		}
+	}
+}
+