Migrate GroupListController to a ViewModel

Use ListAdapter to calculate list diffs on a background thread

briar-android/src/main/java/org/briarproject/briar/android/AppModule.java

@@ -31,6 +31,7 @@ import org.briarproject.briar.android.account.LockManagerImpl;
 import org.briarproject.briar.android.keyagreement.ContactExchangeModule;
 import org.briarproject.briar.android.login.LoginModule;
 import org.briarproject.briar.android.navdrawer.NavDrawerModule;
+import org.briarproject.briar.android.privategroup.list.GroupListModule;
 import org.briarproject.briar.android.reporting.DevReportModule;
 import org.briarproject.briar.android.viewmodel.ViewModelModule;
 import org.briarproject.briar.api.android.AndroidNotificationManager;
@@ -65,7 +66,9 @@ import static org.briarproject.briar.android.TestingConstants.IS_DEBUG_BUILD;
 		LoginModule.class,
 		NavDrawerModule.class,
 		ViewModelModule.class,
-		DevReportModule.class
+		DevReportModule.class,
+		// below need to be within same scope as ViewModelProvider.Factory
+		GroupListModule.class,
 })
 public class AppModule {
 

briar-android/src/main/java/org/briarproject/briar/android/activity/ActivityComponent.java

@@ -60,7 +60,6 @@ import org.briarproject.briar.android.privategroup.creation.GroupInviteFragment;
 import org.briarproject.briar.android.privategroup.invitation.GroupInvitationActivity;
 import org.briarproject.briar.android.privategroup.invitation.GroupInvitationModule;
 import org.briarproject.briar.android.privategroup.list.GroupListFragment;
-import org.briarproject.briar.android.privategroup.list.GroupListModule;
 import org.briarproject.briar.android.privategroup.memberlist.GroupMemberListActivity;
 import org.briarproject.briar.android.privategroup.memberlist.GroupMemberModule;
 import org.briarproject.briar.android.privategroup.reveal.GroupRevealModule;
@@ -94,7 +93,6 @@ import dagger.Component;
 		ForumModule.class,
 		GroupInvitationModule.class,
 		GroupConversationModule.class,
-		GroupListModule.class,
 		GroupMemberModule.class,
 		GroupRevealModule.class,
 		SharingModule.class

briar-android/src/main/java/org/briarproject/briar/android/privategroup/list/GroupItem.java

@@ -8,9 +8,11 @@ import org.briarproject.briar.api.client.MessageTracker.GroupCount;
 import org.briarproject.briar.api.privategroup.GroupMessageHeader;
 import org.briarproject.briar.api.privategroup.PrivateGroup;
 
+import androidx.annotation.Nullable;
+
 // This class is not thread-safe
 @NotNullByDefault
-class GroupItem {
+class GroupItem implements Comparable<GroupItem> {
 
 	private final PrivateGroup privateGroup;
 	private final AuthorInfo authorInfo;
@@ -28,6 +30,15 @@ class GroupItem {
 		this.dissolved = dissolved;
 	}
 
+	GroupItem(GroupItem item) {
+		this.privateGroup = item.privateGroup;
+		this.authorInfo = item.authorInfo;
+		this.messageCount = item.messageCount;
+		this.unreadCount = item.unreadCount;
+		this.timestamp = item.timestamp;
+		this.dissolved = item.dissolved;
+	}
+
 	void addMessageHeader(GroupMessageHeader header) {
 		messageCount++;
 		if (header.getTimestamp() > timestamp) {
@@ -38,10 +49,6 @@ class GroupItem {
 		}
 	}
 
-	PrivateGroup getPrivateGroup() {
-		return privateGroup;
-	}
-
 	GroupId getId() {
 		return privateGroup.getId();
 	}
@@ -82,4 +89,22 @@ class GroupItem {
 		dissolved = true;
 	}
 
+	@Override
+	public boolean equals(@Nullable Object o) {
+		return o instanceof GroupItem &&
+				getId().equals(((GroupItem) o).getId());
+	}
+
+	@Override
+	public int compareTo(GroupItem o) {
+		if (this == o) return 0;
+		// The group with the latest message comes first
+		long aTime = getTimestamp(), bTime = o.getTimestamp();
+		if (aTime > bTime) return -1;
+		if (aTime < bTime) return 1;
+		// Break ties by group name
+		String aName = getName();
+		String bName = o.getName();
+		return String.CASE_INSENSITIVE_ORDER.compare(aName, bName);
+	}
 }

briar-android/src/main/java/org/briarproject/briar/android/privategroup/list/GroupListAdapter.java

@@ -1,81 +1,52 @@
 package org.briarproject.briar.android.privategroup.list;
 
-import android.content.Context;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.privategroup.list.GroupViewHolder.OnGroupRemoveClickListener;
-import org.briarproject.briar.android.util.BriarAdapter;
 
-import static androidx.recyclerview.widget.SortedList.INVALID_POSITION;
+import androidx.recyclerview.widget.DiffUtil.ItemCallback;
+import androidx.recyclerview.widget.ListAdapter;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-class GroupListAdapter extends BriarAdapter<GroupItem, GroupViewHolder> {
+class GroupListAdapter extends ListAdapter<GroupItem, GroupViewHolder> {
 
 	private final OnGroupRemoveClickListener listener;
 
-	GroupListAdapter(Context ctx, OnGroupRemoveClickListener listener) {
-		super(ctx, GroupItem.class);
+	GroupListAdapter(OnGroupRemoveClickListener listener) {
+		super(new GroupItemCallback());
 		this.listener = listener;
 	}
 
 	@Override
 	public GroupViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
-		View v = LayoutInflater.from(ctx).inflate(
-				R.layout.list_item_group, parent, false);
+		View v = LayoutInflater.from(parent.getContext())
+				.inflate(R.layout.list_item_group, parent, false);
 		return new GroupViewHolder(v);
 	}
 
 	@Override
 	public void onBindViewHolder(GroupViewHolder ui, int position) {
-		ui.bindView(ctx, items.get(position), listener);
+		ui.bindView(getItem(position), listener);
 	}
 
-	@Override
-	public int compare(GroupItem a, GroupItem b) {
-		if (a == b) return 0;
-		// The group with the latest message comes first
-		long aTime = a.getTimestamp(), bTime = b.getTimestamp();
-		if (aTime > bTime) return -1;
-		if (aTime < bTime) return 1;
-		// Break ties by group name
-		String aName = a.getName();
-		String bName = b.getName();
-		return String.CASE_INSENSITIVE_ORDER.compare(aName, bName);
-	}
-
-	@Override
-	public boolean areContentsTheSame(GroupItem a, GroupItem b) {
-		return a.getMessageCount() == b.getMessageCount() &&
-				a.getTimestamp() == b.getTimestamp() &&
-				a.getUnreadCount() == b.getUnreadCount() &&
-				a.isDissolved() == b.isDissolved();
-	}
-
-	@Override
-	public boolean areItemsTheSame(GroupItem a, GroupItem b) {
-		return a.getId().equals(b.getId());
-	}
-
-	int findItemPosition(GroupId g) {
-		for (int i = 0; i < items.size(); i++) {
-			GroupItem item = items.get(i);
-			if (item.getId().equals(g)) {
-				return i;
-			}
+	private static class GroupItemCallback extends ItemCallback<GroupItem> {
+		@Override
+		public boolean areItemsTheSame(GroupItem a, GroupItem b) {
+			return a.equals(b);
 		}
-		return INVALID_POSITION;
-	}
 
-	void removeItem(GroupId groupId) {
-		int pos = findItemPosition(groupId);
-		if (pos != INVALID_POSITION) items.removeItemAt(pos);
+		@Override
+		public boolean areContentsTheSame(GroupItem a, GroupItem b) {
+			return a.getMessageCount() == b.getMessageCount() &&
+					a.getTimestamp() == b.getTimestamp() &&
+					a.getUnreadCount() == b.getUnreadCount() &&
+					a.isDissolved() == b.isDissolved();
+		}
 	}
-
 }

briar-android/src/main/java/org/briarproject/briar/android/privategroup/list/GroupListController.java

@@ -1,60 +0,0 @@
-package org.briarproject.briar.android.privategroup.list;
-
-import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.sync.GroupId;
-import org.briarproject.briar.android.controller.DbController;
-import org.briarproject.briar.android.controller.handler.ExceptionHandler;
-import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
-import org.briarproject.briar.api.privategroup.GroupMessageHeader;
-
-import java.util.Collection;
-
-import androidx.annotation.UiThread;
-
-@NotNullByDefault
-interface GroupListController extends DbController {
-
-	/**
-	 * The listener must be set right after the controller was injected
-	 */
-	@UiThread
-	void setGroupListListener(GroupListListener listener);
-
-	@UiThread
-	void unsetGroupListListener(GroupListListener listener);
-
-	@UiThread
-	void onStart();
-
-	@UiThread
-	void onStop();
-
-	void loadGroups(
-			ResultExceptionHandler<Collection<GroupItem>, DbException> result);
-
-	void removeGroup(GroupId g, ExceptionHandler<DbException> result);
-
-	void loadAvailableGroups(
-			ResultExceptionHandler<Integer, DbException> result);
-
-	interface GroupListListener {
-
-		@UiThread
-		void onGroupMessageAdded(GroupMessageHeader header);
-
-		@UiThread
-		void onGroupInvitationReceived();
-
-		@UiThread
-		void onGroupAdded(GroupId groupId);
-
-		@UiThread
-		void onGroupRemoved(GroupId groupId);
-
-		@UiThread
-		void onGroupDissolved(GroupId groupId);
-
-	}
-
-}

briar-android/src/main/java/org/briarproject/briar/android/privategroup/list/GroupListFragment.java

@@ -15,54 +15,50 @@ import com.google.android.material.snackbar.Snackbar;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
-import org.briarproject.briar.android.controller.handler.UiExceptionHandler;
-import org.briarproject.briar.android.controller.handler.UiResultExceptionHandler;
 import org.briarproject.briar.android.fragment.BaseFragment;
 import org.briarproject.briar.android.privategroup.creation.CreateGroupActivity;
 import org.briarproject.briar.android.privategroup.invitation.GroupInvitationActivity;
-import org.briarproject.briar.android.privategroup.list.GroupListController.GroupListListener;
 import org.briarproject.briar.android.privategroup.list.GroupViewHolder.OnGroupRemoveClickListener;
 import org.briarproject.briar.android.util.BriarSnackbarBuilder;
 import org.briarproject.briar.android.view.BriarRecyclerView;
-import org.briarproject.briar.api.privategroup.GroupMessageHeader;
 
-import java.util.Collection;
-import java.util.logging.Logger;
+import java.util.List;
 
 import javax.annotation.Nullable;
 import javax.inject.Inject;
 
 import androidx.annotation.UiThread;
+import androidx.lifecycle.ViewModelProvider;
 import androidx.recyclerview.widget.LinearLayoutManager;
 
 import static com.google.android.material.snackbar.Snackbar.LENGTH_INDEFINITE;
+import static java.util.Objects.requireNonNull;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
 public class GroupListFragment extends BaseFragment implements
-		GroupListListener, OnGroupRemoveClickListener, OnClickListener {
+		OnGroupRemoveClickListener, OnClickListener {
 
 	public final static String TAG = GroupListFragment.class.getName();
-	private static final Logger LOG = Logger.getLogger(TAG);
 
 	public static GroupListFragment newInstance() {
 		return new GroupListFragment();
 	}
 
 	@Inject
-	GroupListController controller;
+	ViewModelProvider.Factory viewModelFactory;
 
+	private GroupListViewModel viewModel;
 	private BriarRecyclerView list;
 	private GroupListAdapter adapter;
-	private Snackbar snackbar;
 
 	@Override
 	public void injectFragment(ActivityComponent component) {
 		component.inject(this);
-		controller.setGroupListListener(this);
+		viewModel = new ViewModelProvider(this, viewModelFactory)
+				.get(GroupListViewModel.class);
 	}
 
 	@Nullable
@@ -75,17 +71,35 @@ public class GroupListFragment extends BaseFragment implements
 
 		View v = inflater.inflate(R.layout.list, container, false);
 
-		adapter = new GroupListAdapter(getActivity(), this);
+		adapter = new GroupListAdapter(this);
 		list = v.findViewById(R.id.list);
 		list.setEmptyImage(R.drawable.ic_empty_state_group_list);
 		list.setEmptyText(R.string.groups_list_empty);
 		list.setEmptyAction(R.string.groups_list_empty_action);
 		list.setLayoutManager(new LinearLayoutManager(getContext()));
 		list.setAdapter(adapter);
+		viewModel.getGroupItems().observe(getViewLifecycleOwner(), result -> {
+			List<GroupItem> items = result.getResultOrNull();
+			if (items == null && result.getException() instanceof DbException) {
+				handleDbException((DbException) result.getException());
+			} else {
+				adapter.submitList(items);
+				if (requireNonNull(items).size() == 0) list.showData();
+			}
+		});
 
-		snackbar = new BriarSnackbarBuilder()
+		Snackbar snackbar = new BriarSnackbarBuilder()
 				.setAction(R.string.show, this)
 				.make(list, "", LENGTH_INDEFINITE);
+		viewModel.getNumInvitations().observe(getViewLifecycleOwner(), num -> {
+			if (num == 0) {
+				snackbar.dismiss();
+			} else {
+				snackbar.setText(getResources().getQuantityString(
+						R.plurals.groups_invitations_open, num, num));
+				if (!snackbar.isShownOrQueued()) snackbar.show();
+			}
+		});
 
 		return v;
 	}
@@ -93,25 +107,22 @@ public class GroupListFragment extends BaseFragment implements
 	@Override
 	public void onStart() {
 		super.onStart();
-		controller.onStart();
+		// TODO should we block all group message notifications as well?
+		viewModel.clearAllGroupMessageNotifications();
+		// The attributes and sorting of the groups may have changed while we
+		// were stopped and we have no way finding out about them, so re-load
+		// e.g. less unread messages in a group after viewing it.
+		viewModel.loadGroups();
+		// The number of invitations might have changed while we were stopped
+		// e.g. because of accepting an invitation which does not trigger event
+		viewModel.loadNumInvitations();
 		list.startPeriodicUpdate();
-		loadGroups();
-		loadAvailableGroups();
 	}
 
 	@Override
 	public void onStop() {
 		super.onStop();
-		controller.onStop();
 		list.stopPeriodicUpdate();
-		adapter.clear();
-		list.showProgressBar();
-	}
-
-	@Override
-	public void onDestroy() {
-		super.onDestroy();
-		controller.unsetGroupListListener(this);
 	}
 
 	@Override
@@ -122,68 +133,18 @@ public class GroupListFragment extends BaseFragment implements
 
 	@Override
 	public boolean onOptionsItemSelected(MenuItem item) {
-		switch (item.getItemId()) {
-			case R.id.action_add_group:
-				Intent i = new Intent(getContext(), CreateGroupActivity.class);
-				startActivity(i);
-				return true;
-			default:
-				return super.onOptionsItemSelected(item);
+		if (item.getItemId() == R.id.action_add_group) {
+			Intent i = new Intent(getContext(), CreateGroupActivity.class);
+			startActivity(i);
+			return true;
 		}
+		return super.onOptionsItemSelected(item);
 	}
 
 	@UiThread
 	@Override
 	public void onGroupRemoveClick(GroupItem item) {
-		controller.removeGroup(item.getId(),
-				new UiExceptionHandler<DbException>(this) {
-					// result handled by GroupRemovedEvent and onGroupRemoved()
-					@Override
-					public void onExceptionUi(DbException exception) {
-						handleDbException(exception);
-					}
-				});
-	}
-
-	@UiThread
-	@Override
-	public void onGroupMessageAdded(GroupMessageHeader header) {
-		adapter.incrementRevision();
-		int position = adapter.findItemPosition(header.getGroupId());
-		GroupItem item = adapter.getItemAt(position);
-		if (item != null) {
-			item.addMessageHeader(header);
-			adapter.updateItemAt(position, item);
-		}
-	}
-
-	@Override
-	public void onGroupInvitationReceived() {
-		loadAvailableGroups();
-	}
-
-	@UiThread
-	@Override
-	public void onGroupAdded(GroupId groupId) {
-		loadGroups();
-	}
-
-	@UiThread
-	@Override
-	public void onGroupRemoved(GroupId groupId) {
-		adapter.incrementRevision();
-		adapter.removeItem(groupId);
-	}
-
-	@Override
-	public void onGroupDissolved(GroupId groupId) {
-		adapter.incrementRevision();
-		int position = adapter.findItemPosition(groupId);
-		GroupItem item = adapter.getItemAt(position);
-		if (item != null) {
-			item.setDissolved();
-			adapter.updateItemAt(position, item);
-		}
+		viewModel.removeGroup(item.getId());
 	}
 
 	@Override
@@ -191,57 +152,13 @@ public class GroupListFragment extends BaseFragment implements
 		return TAG;
 	}
 
-	private void loadGroups() {
-		int revision = adapter.getRevision();
-		controller.loadGroups(
-				new UiResultExceptionHandler<Collection<GroupItem>, DbException>(
-						this) {
-					@Override
-					public void onResultUi(Collection<GroupItem> groups) {
-						if (revision == adapter.getRevision()) {
-							adapter.incrementRevision();
-							if (groups.isEmpty()) list.showData();
-							else adapter.replaceAll(groups);
-						} else {
-							LOG.info("Concurrent update, reloading");
-							loadGroups();
-						}
-					}
-
-					@Override
-					public void onExceptionUi(DbException exception) {
-						handleDbException(exception);
-					}
-				});
-	}
-
-	private void loadAvailableGroups() {
-		controller.loadAvailableGroups(
-				new UiResultExceptionHandler<Integer, DbException>(this) {
-					@Override
-					public void onResultUi(Integer num) {
-						if (num == 0) {
-							snackbar.dismiss();
-						} else {
-							snackbar.setText(getResources().getQuantityString(
-									R.plurals.groups_invitations_open, num,
-									num));
-							if (!snackbar.isShownOrQueued()) snackbar.show();
-						}
-					}
-
-					@Override
-					public void onExceptionUi(DbException exception) {
-						handleDbException(exception);
-					}
-				});
-	}
-
 	/**
 	 * This method is handling the available groups snackbar action
 	 */
 	@Override
 	public void onClick(View v) {
+		// The snackbar dismisses itself when this is called
+		// and does not come back until the fragment gets recreated.
 		Intent i = new Intent(getContext(), GroupInvitationActivity.class);
 		startActivity(i);
 	}

briar-android/src/main/java/org/briarproject/briar/android/privategroup/list/GroupListModule.java

@@ -1,17 +1,18 @@
 package org.briarproject.briar.android.privategroup.list;
 
-import org.briarproject.briar.android.activity.ActivityScope;
+import org.briarproject.briar.android.viewmodel.ViewModelKey;
 
+import androidx.lifecycle.ViewModel;
+import dagger.Binds;
 import dagger.Module;
-import dagger.Provides;
+import dagger.multibindings.IntoMap;
 
 @Module
-public class GroupListModule {
+public abstract class GroupListModule {
 
-	@ActivityScope
-	@Provides
-	GroupListController provideGroupListController(
-			GroupListControllerImpl groupListController) {
-		return groupListController;
-	}
+	@Binds
+	@IntoMap
+	@ViewModelKey(GroupListViewModel.class)
+	abstract ViewModel bindGroupListViewModel(
+			GroupListViewModel groupListViewModel);
 }

briar-android/src/main/java/org/briarproject/briar/android/privategroup/list/GroupListViewModel.java

@@ -1,5 +1,7 @@
 package org.briarproject.briar.android.privategroup.list;
 
+import android.app.Application;
+
 import org.briarproject.bramble.api.contact.ContactManager;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
@@ -18,11 +20,11 @@ import org.briarproject.bramble.api.sync.ClientId;
 import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.event.GroupAddedEvent;
 import org.briarproject.bramble.api.sync.event.GroupRemovedEvent;
-import org.briarproject.briar.android.controller.DbControllerImpl;
-import org.briarproject.briar.android.controller.handler.ExceptionHandler;
-import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
+import org.briarproject.briar.android.viewmodel.DbViewModel;
+import org.briarproject.briar.android.viewmodel.LiveResult;
 import org.briarproject.briar.api.android.AndroidNotificationManager;
 import org.briarproject.briar.api.client.MessageTracker.GroupCount;
+import org.briarproject.briar.api.privategroup.GroupMessageHeader;
 import org.briarproject.briar.api.privategroup.PrivateGroup;
 import org.briarproject.briar.api.privategroup.PrivateGroupManager;
 import org.briarproject.briar.api.privategroup.event.GroupDissolvedEvent;
@@ -32,6 +34,7 @@ import org.briarproject.briar.api.privategroup.invitation.GroupInvitationManager
 
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -40,10 +43,13 @@ import java.util.logging.Logger;
 
 import javax.inject.Inject;
 
-import androidx.annotation.CallSuper;
-import androidx.annotation.Nullable;
+import androidx.annotation.UiThread;
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
 
+import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.LogUtils.now;
@@ -51,113 +57,86 @@ import static org.briarproject.briar.api.privategroup.PrivateGroupManager.CLIENT
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-class GroupListControllerImpl extends DbControllerImpl
-		implements GroupListController, EventListener {
+class GroupListViewModel extends DbViewModel implements EventListener {
 
 	private static final Logger LOG =
-			Logger.getLogger(GroupListControllerImpl.class.getName());
+			getLogger(GroupListViewModel.class.getName());
 
-	private final TransactionManager db;
 	private final PrivateGroupManager groupManager;
 	private final GroupInvitationManager groupInvitationManager;
 	private final ContactManager contactManager;
 	private final AndroidNotificationManager notificationManager;
 	private final EventBus eventBus;
 
-	// UI thread
-	@Nullable
-	private GroupListListener listener;
+	private final MutableLiveData<LiveResult<List<GroupItem>>> groupItems =
+			new MutableLiveData<>();
+	private final MutableLiveData<Integer> numInvitations =
+			new MutableLiveData<>();
 
 	@Inject
-	GroupListControllerImpl(@DatabaseExecutor Executor dbExecutor,
+	GroupListViewModel(Application application,
+			@DatabaseExecutor Executor dbExecutor,
 			LifecycleManager lifecycleManager,
 			TransactionManager db,
 			PrivateGroupManager groupManager,
 			GroupInvitationManager groupInvitationManager,
 			ContactManager contactManager,
 			AndroidNotificationManager notificationManager, EventBus eventBus) {
-		super(dbExecutor, lifecycleManager);
-		this.db = db;
+		super(application, dbExecutor, lifecycleManager, db);
 		this.groupManager = groupManager;
 		this.groupInvitationManager = groupInvitationManager;
 		this.contactManager = contactManager;
 		this.notificationManager = notificationManager;
 		this.eventBus = eventBus;
+		this.eventBus.addListener(this);
 	}
 
 	@Override
-	public void setGroupListListener(GroupListListener listener) {
-		this.listener = listener;
+	protected void onCleared() {
+		super.onCleared();
+		eventBus.removeListener(this);
 	}
 
-	@Override
-	public void unsetGroupListListener(GroupListListener listener) {
-		if (this.listener == listener) this.listener = null;
-	}
-
-	@Override
-	@CallSuper
-	public void onStart() {
-		if (listener == null) throw new IllegalStateException();
-		eventBus.addListener(this);
+	void clearAllGroupMessageNotifications() {
 		notificationManager.clearAllGroupMessageNotifications();
 	}
 
 	@Override
-	@CallSuper
-	public void onStop() {
-		eventBus.removeListener(this);
-	}
-
-	@Override
-	@CallSuper
 	public void eventOccurred(Event e) {
-		if (listener == null) throw new IllegalStateException();
 		if (e instanceof GroupMessageAddedEvent) {
 			GroupMessageAddedEvent g = (GroupMessageAddedEvent) e;
 			LOG.info("Private group message added");
-			listener.onGroupMessageAdded(g.getHeader());
+			onGroupMessageAdded(g.getHeader());
 		} else if (e instanceof GroupInvitationRequestReceivedEvent) {
 			LOG.info("Private group invitation received");
-			listener.onGroupInvitationReceived();
+			loadNumInvitations();
 		} else if (e instanceof GroupAddedEvent) {
 			GroupAddedEvent g = (GroupAddedEvent) e;
 			ClientId id = g.getGroup().getClientId();
 			if (id.equals(CLIENT_ID)) {
 				LOG.info("Private group added");
-				listener.onGroupAdded(g.getGroup().getId());
+				loadGroups();
 			}
 		} else if (e instanceof GroupRemovedEvent) {
 			GroupRemovedEvent g = (GroupRemovedEvent) e;
 			ClientId id = g.getGroup().getClientId();
 			if (id.equals(CLIENT_ID)) {
 				LOG.info("Private group removed");
-				listener.onGroupRemoved(g.getGroup().getId());
+				onGroupRemoved(g.getGroup().getId());
 			}
 		} else if (e instanceof GroupDissolvedEvent) {
 			GroupDissolvedEvent g = (GroupDissolvedEvent) e;
 			LOG.info("Private group dissolved");
-			listener.onGroupDissolved(g.getGroupId());
+			onGroupDissolved(g.getGroupId());
 		}
 	}
 
-	@Override
-	public void loadGroups(
-			ResultExceptionHandler<Collection<GroupItem>, DbException> handler) {
-		runOnDbThread(() -> {
-			try {
-				db.transaction(true, txn -> loadGroups(txn, handler));
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-				handler.onException(e);
-			}
-		});
+	void loadGroups() {
+		loadList(this::loadGroups, groupItems::setValue);
 	}
 
 	@DatabaseExecutor
-	private void loadGroups(Transaction txn,
-			ResultExceptionHandler<Collection<GroupItem>, DbException> handler)
-			throws DbException {
+	private List<GroupItem> loadGroups(Transaction txn) throws DbException {
 		long start = now();
 		Collection<PrivateGroup> groups = groupManager.getPrivateGroups(txn);
 		List<GroupItem> items = new ArrayList<>(groups.size());
@@ -168,7 +147,7 @@ class GroupListControllerImpl extends DbControllerImpl
 				AuthorId authorId = g.getCreator().getId();
 				AuthorInfo authorInfo;
 				if (authorInfos.containsKey(authorId)) {
-					authorInfo = authorInfos.get(authorId);
+					authorInfo = requireNonNull(authorInfos.get(authorId));
 				} else {
 					authorInfo = contactManager.getAuthorInfo(txn, authorId);
 					authorInfos.put(authorId, authorInfo);
@@ -180,12 +159,49 @@ class GroupListControllerImpl extends DbControllerImpl
 				// Continue
 			}
 		}
+		Collections.sort(items);
 		logDuration(LOG, "Loading groups", start);
-		handler.onResult(items);
+		return items;
 	}
 
-	@Override
-	public void removeGroup(GroupId g, ExceptionHandler<DbException> handler) {
+	@UiThread
+	private void onGroupMessageAdded(GroupMessageHeader header) {
+		GroupId g = header.getGroupId();
+		List<GroupItem> list = updateListItem(groupItems,
+				itemToTest -> itemToTest.getId().equals(g),
+				itemToUpdate -> {
+					GroupItem newItem = new GroupItem(itemToUpdate);
+					newItem.addMessageHeader(header);
+					return newItem;
+				});
+		if (list == null) return;
+		// re-sort as the order of items may have changed
+		Collections.sort(list);
+		groupItems.setValue(new LiveResult<>(list));
+	}
+
+	@UiThread
+	private void onGroupDissolved(GroupId groupId) {
+		List<GroupItem> list = updateListItem(groupItems,
+				itemToTest -> itemToTest.getId().equals(groupId),
+				itemToUpdate -> {
+					GroupItem newItem = new GroupItem(itemToUpdate);
+					newItem.setDissolved();
+					return newItem;
+				});
+		if (list == null) return;
+		groupItems.setValue(new LiveResult<>(list));
+	}
+
+	@UiThread
+	private void onGroupRemoved(GroupId groupId) {
+		List<GroupItem> list =
+				removeListItem(groupItems, i -> i.getId().equals(groupId));
+		if (list == null) return;
+		groupItems.setValue(new LiveResult<>(list));
+	}
+
+	void removeGroup(GroupId g) {
 		runOnDbThread(() -> {
 			try {
 				long start = now();
@@ -193,23 +209,26 @@ class GroupListControllerImpl extends DbControllerImpl
 				logDuration(LOG, "Removing group", start);
 			} catch (DbException e) {
 				logException(LOG, WARNING, e);
-				handler.onException(e);
 			}
 		});
 	}
 
-	@Override
-	public void loadAvailableGroups(
-			ResultExceptionHandler<Integer, DbException> handler) {
+	void loadNumInvitations() {
 		runOnDbThread(() -> {
 			try {
-				handler.onResult(
-						groupInvitationManager.getInvitations().size());
+				int i = groupInvitationManager.getInvitations().size();
+				numInvitations.postValue(i);
 			} catch (DbException e) {
 				logException(LOG, WARNING, e);
-				handler.onException(e);
 			}
 		});
 	}
 
+	LiveData<LiveResult<List<GroupItem>>> getGroupItems() {
+		return groupItems;
+	}
+
+	LiveData<Integer> getNumInvitations() {
+		return numInvitations;
+	}
 }

briar-android/src/main/java/org/briarproject/briar/android/privategroup/list/GroupViewHolder.java

@@ -29,6 +29,7 @@ class GroupViewHolder extends RecyclerView.ViewHolder {
 
 	private final static float ALPHA = 0.42f;
 
+	private final Context ctx;
 	private final ViewGroup layout;
 	private final TextAvatarView avatar;
 	private final TextView name;
@@ -40,7 +41,7 @@ class GroupViewHolder extends RecyclerView.ViewHolder {
 
 	GroupViewHolder(View v) {
 		super(v);
-
+		ctx = v.getContext();
 		layout = (ViewGroup) v;
 		avatar = v.findViewById(R.id.avatarView);
 		name = v.findViewById(R.id.nameView);
@@ -51,8 +52,7 @@ class GroupViewHolder extends RecyclerView.ViewHolder {
 		remove = v.findViewById(R.id.removeButton);
 	}
 
-	void bindView(Context ctx, GroupItem group,
-			OnGroupRemoveClickListener listener) {
+	void bindView(GroupItem group, OnGroupRemoveClickListener listener) {
 		// Avatar
 		avatar.setText(group.getName().substring(0, 1));
 		avatar.setBackgroundBytes(group.getId().getBytes());