Introduce ForumListViewModel

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

@@ -28,6 +28,7 @@ import org.briarproject.bramble.plugin.tor.AndroidTorPluginFactory;
 import org.briarproject.bramble.util.AndroidUtils;
 import org.briarproject.bramble.util.StringUtils;
 import org.briarproject.briar.android.account.LockManagerImpl;
+import org.briarproject.briar.android.forum.ForumModule;
 import org.briarproject.briar.android.keyagreement.ContactExchangeModule;
 import org.briarproject.briar.android.login.LoginModule;
 import org.briarproject.briar.android.navdrawer.NavDrawerModule;
@@ -68,6 +69,7 @@ import static org.briarproject.briar.android.TestingConstants.IS_DEBUG_BUILD;
 		ViewModelModule.class,
 		DevReportModule.class,
 		// below need to be within same scope as ViewModelProvider.Factory
+		ForumModule.BindsModule.class,
 		GroupListModule.class,
 })
 public class AppModule {

briar-android/src/main/java/org/briarproject/briar/android/forum/ForumListAdapter.java

@@ -1,134 +1,47 @@
 package org.briarproject.briar.android.forum;
 
-import android.content.Context;
-import android.content.Intent;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
-import android.widget.TextView;
 
-import org.briarproject.bramble.api.sync.GroupId;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
-import org.briarproject.briar.android.util.BriarAdapter;
-import org.briarproject.briar.android.util.UiUtils;
-import org.briarproject.briar.android.view.TextAvatarView;
-import org.briarproject.briar.api.forum.Forum;
 
-import androidx.recyclerview.widget.RecyclerView;
+import androidx.recyclerview.widget.DiffUtil.ItemCallback;
+import androidx.recyclerview.widget.ListAdapter;
 
-import static android.view.View.GONE;
+@NotNullByDefault
-import static android.view.View.VISIBLE;
+class ForumListAdapter extends ListAdapter<ForumListItem, ForumViewHolder> {
-import static androidx.recyclerview.widget.SortedList.INVALID_POSITION;
-import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
-import static org.briarproject.briar.android.activity.BriarActivity.GROUP_NAME;
 
-class ForumListAdapter
+	ForumListAdapter() {
-		extends BriarAdapter<ForumListItem, ForumListAdapter.ForumViewHolder> {
+		super(new ForumListCallback());
-
-	ForumListAdapter(Context ctx) {
-		super(ctx, ForumListItem.class);
 	}
 
 	@Override
 	public ForumViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
-		View v = LayoutInflater.from(ctx).inflate(
+		View v = LayoutInflater.from(parent.getContext()).inflate(
 				R.layout.list_item_forum, parent, false);
 		return new ForumViewHolder(v);
 	}
 
 	@Override
-	public void onBindViewHolder(ForumViewHolder ui, int position) {
+	public void onBindViewHolder(ForumViewHolder viewHolder, int position) {
-		ForumListItem item = getItemAt(position);
+		viewHolder.bind(getItem(position));
-		if (item == null) return;
+	}
 
-		// Avatar
+	@NotNullByDefault
-		ui.avatar.setText(item.getForum().getName().substring(0, 1));
+	private static class ForumListCallback extends ItemCallback<ForumListItem> {
-		ui.avatar.setBackgroundBytes(item.getForum().getId().getBytes());
+		@Override
-		ui.avatar.setUnreadCount(item.getUnreadCount());
+		public boolean areItemsTheSame(ForumListItem a, ForumListItem b) {
-
+			return a.equals(b);
-		// Forum Name
-		ui.name.setText(item.getForum().getName());
-
-		// Post Count
-		int postCount = item.getPostCount();
-		if (postCount > 0) {
-			ui.postCount.setText(ctx.getResources()
-					.getQuantityString(R.plurals.posts, postCount,
-							postCount));
-		} else {
-			ui.postCount.setText(ctx.getString(R.string.no_posts));
 		}
 
-		// Date
+		@Override
-		if (item.isEmpty()) {
+		public boolean areContentsTheSame(ForumListItem a, ForumListItem b) {
-			ui.date.setVisibility(GONE);
+			return a.isEmpty() == b.isEmpty() &&
-		} else {
+					a.getTimestamp() == b.getTimestamp() &&
-			long timestamp = item.getTimestamp();
+					a.getUnreadCount() == b.getUnreadCount();
-			ui.date.setText(UiUtils.formatDate(ctx, timestamp));
-			ui.date.setVisibility(VISIBLE);
-		}
-
-		// Open Forum on Click
-		ui.layout.setOnClickListener(v -> {
-			Intent i = new Intent(ctx, ForumActivity.class);
-			Forum f = item.getForum();
-			i.putExtra(GROUP_ID, f.getId().getBytes());
-			i.putExtra(GROUP_NAME, f.getName());
-			ctx.startActivity(i);
-		});
-	}
-
-	@Override
-	public int compare(ForumListItem a, ForumListItem b) {
-		if (a == b) return 0;
-		// The forum with the newest message comes first
-		long aTime = a.getTimestamp(), bTime = b.getTimestamp();
-		if (aTime > bTime) return -1;
-		if (aTime < bTime) return 1;
-		// Break ties by forum name
-		String aName = a.getForum().getName();
-		String bName = b.getForum().getName();
-		return String.CASE_INSENSITIVE_ORDER.compare(aName, bName);
-	}
-
-	@Override
-	public boolean areContentsTheSame(ForumListItem a, ForumListItem b) {
-		return a.isEmpty() == b.isEmpty() &&
-				a.getTimestamp() == b.getTimestamp() &&
-				a.getUnreadCount() == b.getUnreadCount();
-	}
-
-	@Override
-	public boolean areItemsTheSame(ForumListItem a, ForumListItem b) {
-		return a.getForum().equals(b.getForum());
-	}
-
-	int findItemPosition(GroupId g) {
-		int count = getItemCount();
-		for (int i = 0; i < count; i++) {
-			ForumListItem item = getItemAt(i);
-			if (item != null && item.getForum().getGroup().getId().equals(g))
-				return i;
-		}
-		return INVALID_POSITION; // Not found
-	}
-
-	static class ForumViewHolder extends RecyclerView.ViewHolder {
-
-		private final ViewGroup layout;
-		private final TextAvatarView avatar;
-		private final TextView name;
-		private final TextView postCount;
-		private final TextView date;
-
-		private ForumViewHolder(View v) {
-			super(v);
-
-			layout = (ViewGroup) v;
-			avatar = v.findViewById(R.id.avatarView);
-			name = v.findViewById(R.id.forumNameView);
-			postCount = v.findViewById(R.id.postCountView);
-			date = v.findViewById(R.id.dateView);
 		}
 	}
+
 }

briar-android/src/main/java/org/briarproject/briar/android/forum/ForumListFragment.java

@@ -12,80 +12,48 @@ import android.view.ViewGroup;
 
 import com.google.android.material.snackbar.Snackbar;
 
-import org.briarproject.bramble.api.contact.event.ContactRemovedEvent;
-import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.db.NoSuchGroupException;
-import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-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.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
-import org.briarproject.briar.android.fragment.BaseEventFragment;
+import org.briarproject.briar.android.fragment.BaseFragment;
 import org.briarproject.briar.android.sharing.ForumInvitationActivity;
 import org.briarproject.briar.android.util.BriarSnackbarBuilder;
 import org.briarproject.briar.android.view.BriarRecyclerView;
-import org.briarproject.briar.api.android.AndroidNotificationManager;
-import org.briarproject.briar.api.client.MessageTracker.GroupCount;
-import org.briarproject.briar.api.forum.Forum;
-import org.briarproject.briar.api.forum.ForumManager;
-import org.briarproject.briar.api.forum.ForumPostHeader;
-import org.briarproject.briar.api.forum.ForumSharingManager;
-import org.briarproject.briar.api.forum.event.ForumInvitationRequestReceivedEvent;
-import org.briarproject.briar.api.forum.event.ForumPostReceivedEvent;
-
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.logging.Logger;
 
 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.logging.Level.WARNING;
+import static java.util.Objects.requireNonNull;
-import static org.briarproject.bramble.util.LogUtils.logDuration;
-import static org.briarproject.bramble.util.LogUtils.logException;
-import static org.briarproject.bramble.util.LogUtils.now;
-import static org.briarproject.briar.api.forum.ForumManager.CLIENT_ID;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-public class ForumListFragment extends BaseEventFragment implements
+public class ForumListFragment extends BaseFragment implements
 		OnClickListener {
 
 	public final static String TAG = ForumListFragment.class.getName();
-	private final static Logger LOG = Logger.getLogger(TAG);
 
+	private ForumListViewModel viewModel;
 	private BriarRecyclerView list;
-	private ForumListAdapter adapter;
 	private Snackbar snackbar;
+	private final ForumListAdapter adapter = new ForumListAdapter();
 
 	@Inject
-	AndroidNotificationManager notificationManager;
+	ViewModelProvider.Factory viewModelFactory;
-
-	// Fields that are accessed from background threads must be volatile
-	@Inject
-	volatile ForumManager forumManager;
-	@Inject
-	volatile ForumSharingManager forumSharingManager;
 
 	public static ForumListFragment newInstance() {
-
+		return new ForumListFragment();
-		Bundle args = new Bundle();
-
-		ForumListFragment fragment = new ForumListFragment();
-		fragment.setArguments(args);
-		return fragment;
 	}
 
 	@Override
 	public void injectFragment(ActivityComponent component) {
 		component.inject(this);
+		viewModel = new ViewModelProvider(this, viewModelFactory)
+				.get(ForumListViewModel.class);
 	}
 
 	@Nullable
@@ -93,24 +61,35 @@ public class ForumListFragment extends BaseEventFragment implements
 	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
-
 		requireActivity().setTitle(R.string.forums_button);
 
-		View contentView =
+		View v = inflater.inflate(R.layout.fragment_forum_list, container,
-				inflater.inflate(R.layout.fragment_forum_list, container,
+				false);
-						false);
 
-		adapter = new ForumListAdapter(getActivity());
+		list = v.findViewById(R.id.forumList);
-
-		list = contentView.findViewById(R.id.forumList);
 		list.setLayoutManager(new LinearLayoutManager(getActivity()));
 		list.setAdapter(adapter);
+		viewModel.getForumListItems().observe(getViewLifecycleOwner(), result ->
+				result.onError(this::handleException).onSuccess(items -> {
+					adapter.submitList(items);
+					if (requireNonNull(items).size() == 0) list.showData();
+				})
+		);
 
 		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.forums_shared, num, num));
+				if (!snackbar.isShownOrQueued()) snackbar.show();
+			}
+		});
 
-		return contentView;
+		return v;
 	}
 
 	@Override
@@ -121,19 +100,23 @@ public class ForumListFragment extends BaseEventFragment implements
 	@Override
 	public void onStart() {
 		super.onStart();
-		// TODO block all forum post notifications as well
+		viewModel.blockAllForumPostNotifications();
-		notificationManager.clearAllForumPostNotifications();
+		viewModel.clearAllForumPostNotifications();
-		loadForums();
+		// The attributes and sorting of the forums may have changed while we
-		loadAvailableForums();
+		// were stopped and we have no way finding out about them, so re-load
+		// e.g. less unread posts in a forum after viewing it.
+		viewModel.loadForums();
+		// The number of invitations might have changed while we were stopped
+		// e.g. because of accepting an invitation which does not trigger event
+		viewModel.loadForumInvitations();
 		list.startPeriodicUpdate();
 	}
 
 	@Override
 	public void onStop() {
 		super.onStop();
-		adapter.clear();
-		list.showProgressBar();
 		list.stopPeriodicUpdate();
+		viewModel.unblockAllForumPostNotifications();
 	}
 
 	@Override
@@ -145,123 +128,12 @@ public class ForumListFragment extends BaseEventFragment implements
 	@Override
 	public boolean onOptionsItemSelected(MenuItem item) {
 		// Handle presses on the action bar items
-		switch (item.getItemId()) {
+		if (item.getItemId() == R.id.action_create_forum) {
-			case R.id.action_create_forum:
+			Intent intent = new Intent(getContext(), CreateForumActivity.class);
-				Intent intent =
+			startActivity(intent);
-						new Intent(getContext(), CreateForumActivity.class);
+			return true;
-				startActivity(intent);
-				return true;
-			default:
-				return super.onOptionsItemSelected(item);
 		}
-	}
+		return super.onOptionsItemSelected(item);
-
-	private void loadForums() {
-		int revision = adapter.getRevision();
-		listener.runOnDbThread(() -> {
-			try {
-				long start = now();
-				Collection<ForumListItem> forums = new ArrayList<>();
-				for (Forum f : forumManager.getForums()) {
-					try {
-						GroupCount count =
-								forumManager.getGroupCount(f.getId());
-						forums.add(new ForumListItem(f, count));
-					} catch (NoSuchGroupException e) {
-						// Continue
-					}
-				}
-				logDuration(LOG, "Full load", start);
-				displayForums(revision, forums);
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-			}
-		});
-	}
-
-	private void displayForums(int revision, Collection<ForumListItem> forums) {
-		runOnUiThreadUnlessDestroyed(() -> {
-			if (revision == adapter.getRevision()) {
-				adapter.incrementRevision();
-				if (forums.isEmpty()) list.showData();
-				else adapter.replaceAll(forums);
-			} else {
-				LOG.info("Concurrent update, reloading");
-				loadForums();
-			}
-		});
-	}
-
-	private void loadAvailableForums() {
-		listener.runOnDbThread(() -> {
-			try {
-				long start = now();
-				int available = forumSharingManager.getInvitations().size();
-				logDuration(LOG, "Loading available", start);
-				displayAvailableForums(available);
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-			}
-		});
-	}
-
-	private void displayAvailableForums(int availableCount) {
-		runOnUiThreadUnlessDestroyed(() -> {
-			if (availableCount == 0) {
-				snackbar.dismiss();
-			} else {
-				snackbar.setText(getResources().getQuantityString(
-						R.plurals.forums_shared, availableCount,
-						availableCount));
-				if (!snackbar.isShownOrQueued()) snackbar.show();
-			}
-		});
-	}
-
-	@Override
-	public void eventOccurred(Event e) {
-		if (e instanceof ContactRemovedEvent) {
-			LOG.info("Contact removed, reloading available forums");
-			loadAvailableForums();
-		} else if (e instanceof GroupAddedEvent) {
-			GroupAddedEvent g = (GroupAddedEvent) e;
-			if (g.getGroup().getClientId().equals(CLIENT_ID)) {
-				LOG.info("Forum added, reloading forums");
-				loadForums();
-			}
-		} else if (e instanceof GroupRemovedEvent) {
-			GroupRemovedEvent g = (GroupRemovedEvent) e;
-			if (g.getGroup().getClientId().equals(CLIENT_ID)) {
-				LOG.info("Forum removed, removing from list");
-				removeForum(g.getGroup().getId());
-			}
-		} else if (e instanceof ForumPostReceivedEvent) {
-			ForumPostReceivedEvent f = (ForumPostReceivedEvent) e;
-			LOG.info("Forum post added, updating item");
-			updateItem(f.getGroupId(), f.getHeader());
-		} else if (e instanceof ForumInvitationRequestReceivedEvent) {
-			LOG.info("Forum invitation received, reloading available forums");
-			loadAvailableForums();
-		}
-	}
-
-	@UiThread
-	private void updateItem(GroupId g, ForumPostHeader m) {
-		adapter.incrementRevision();
-		int position = adapter.findItemPosition(g);
-		ForumListItem item = adapter.getItemAt(position);
-		if (item != null) {
-			item.addHeader(m);
-			adapter.updateItemAt(position, item);
-		}
-	}
-
-	@UiThread
-	private void removeForum(GroupId g) {
-		adapter.incrementRevision();
-		int position = adapter.findItemPosition(g);
-		ForumListItem item = adapter.getItemAt(position);
-		if (item != null) adapter.remove(item);
 	}
 
 	@Override

briar-android/src/main/java/org/briarproject/briar/android/forum/ForumListItem.java

@@ -4,12 +4,16 @@ import org.briarproject.briar.api.client.MessageTracker.GroupCount;
 import org.briarproject.briar.api.forum.Forum;
 import org.briarproject.briar.api.forum.ForumPostHeader;
 
-// This class is NOT thread-safe
+import javax.annotation.concurrent.Immutable;
-class ForumListItem {
+
+import androidx.annotation.Nullable;
+
+@Immutable
+class ForumListItem implements Comparable<ForumListItem> {
 
 	private final Forum forum;
-	private int postCount, unread;
+	private final int postCount, unread;
-	private long timestamp;
+	private final long timestamp;
 
 	ForumListItem(Forum forum, GroupCount count) {
 		this.forum = forum;
@@ -18,10 +22,11 @@ class ForumListItem {
 		this.timestamp = count.getLatestMsgTime();
 	}
 
-	void addHeader(ForumPostHeader h) {
+	ForumListItem(ForumListItem item, ForumPostHeader h) {
-		postCount++;
+		this.forum = item.forum;
-		if (!h.isRead()) unread++;
+		this.postCount = item.postCount + 1;
-		if (h.getTimestamp() > timestamp) timestamp = h.getTimestamp();
+		this.unread = item.unread + (h.isRead() ? 0 : 1);
+		this.timestamp = Math.max(item.timestamp, h.getTimestamp());
 	}
 
 	Forum getForum() {
@@ -43,4 +48,29 @@ class ForumListItem {
 	int getUnreadCount() {
 		return unread;
 	}
+
+	@Override
+	public int hashCode() {
+		return forum.getId().hashCode();
+	}
+
+	@Override
+	public boolean equals(@Nullable Object o) {
+		return o instanceof ForumListItem && getForum().equals(
+				((ForumListItem) o).getForum());
+	}
+
+	@Override
+	public int compareTo(ForumListItem o) {
+		if (this == o) return 0;
+		// The forum with the newest message comes first
+		long aTime = getTimestamp(), bTime = o.getTimestamp();
+		if (aTime > bTime) return -1;
+		if (aTime < bTime) return 1;
+		// Break ties by forum name
+		String aName = getForum().getName();
+		String bName = o.getForum().getName();
+		return String.CASE_INSENSITIVE_ORDER.compare(aName, bName);
+	}
+
 }

briar-android/src/main/java/org/briarproject/briar/android/forum/ForumListViewModel.java

@@ -0,0 +1,187 @@
+package org.briarproject.briar.android.forum;
+
+import android.app.Application;
+
+import org.briarproject.bramble.api.contact.event.ContactRemovedEvent;
+import org.briarproject.bramble.api.db.DatabaseExecutor;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.Transaction;
+import org.briarproject.bramble.api.db.TransactionManager;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.event.EventListener;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+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.bramble.api.system.AndroidExecutor;
+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.forum.Forum;
+import org.briarproject.briar.api.forum.ForumManager;
+import org.briarproject.briar.api.forum.ForumPostHeader;
+import org.briarproject.briar.api.forum.ForumSharingManager;
+import org.briarproject.briar.api.forum.event.ForumInvitationRequestReceivedEvent;
+import org.briarproject.briar.api.forum.event.ForumPostReceivedEvent;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.inject.Inject;
+
+import androidx.annotation.UiThread;
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
+
+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;
+import static org.briarproject.briar.api.forum.ForumManager.CLIENT_ID;
+
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+class ForumListViewModel extends DbViewModel implements EventListener {
+
+	private static final Logger LOG =
+			getLogger(ForumListViewModel.class.getName());
+
+	private final ForumManager forumManager;
+	private final ForumSharingManager forumSharingManager;
+	private final AndroidNotificationManager notificationManager;
+	private final EventBus eventBus;
+
+	private final MutableLiveData<LiveResult<List<ForumListItem>>> forumItems =
+			new MutableLiveData<>();
+	private final MutableLiveData<Integer> numInvitations =
+			new MutableLiveData<>();
+
+	@Inject
+	ForumListViewModel(Application application,
+			@DatabaseExecutor Executor dbExecutor,
+			LifecycleManager lifecycleManager,
+			TransactionManager db,
+			AndroidExecutor androidExecutor,
+			ForumManager forumManager,
+			ForumSharingManager forumSharingManager,
+			AndroidNotificationManager notificationManager, EventBus eventBus) {
+		super(application, dbExecutor, lifecycleManager, db, androidExecutor);
+		this.forumManager = forumManager;
+		this.forumSharingManager = forumSharingManager;
+		this.notificationManager = notificationManager;
+		this.eventBus = eventBus;
+		this.eventBus.addListener(this);
+	}
+
+	@Override
+	protected void onCleared() {
+		super.onCleared();
+		eventBus.removeListener(this);
+	}
+
+	void clearAllForumPostNotifications() {
+		notificationManager.clearAllForumPostNotifications();
+	}
+
+	void blockAllForumPostNotifications() {
+		// TODO
+	}
+
+	void unblockAllForumPostNotifications() {
+		// TODO
+	}
+
+	@Override
+	public void eventOccurred(Event e) {
+		if (e instanceof ContactRemovedEvent) {
+			LOG.info("Contact removed, reloading available forums");
+			loadForumInvitations();
+		} else if (e instanceof ForumInvitationRequestReceivedEvent) {
+			LOG.info("Forum invitation received, reloading available forums");
+			loadForumInvitations();
+		} else if (e instanceof GroupAddedEvent) {
+			GroupAddedEvent g = (GroupAddedEvent) e;
+			if (g.getGroup().getClientId().equals(CLIENT_ID)) {
+				LOG.info("Forum added, reloading forums");
+				loadForums();
+			}
+		} else if (e instanceof GroupRemovedEvent) {
+			GroupRemovedEvent g = (GroupRemovedEvent) e;
+			if (g.getGroup().getClientId().equals(CLIENT_ID)) {
+				LOG.info("Forum removed, removing from list");
+				onGroupRemoved(g.getGroup().getId());
+			}
+		} else if (e instanceof ForumPostReceivedEvent) {
+			ForumPostReceivedEvent f = (ForumPostReceivedEvent) e;
+			LOG.info("Forum post added, updating item");
+			onForumPostReceived(f.getGroupId(), f.getHeader());
+		}
+	}
+
+	public void loadForums() {
+		loadList(this::loadForums, forumItems::setValue);
+	}
+
+	@DatabaseExecutor
+	private List<ForumListItem> loadForums(Transaction txn) throws DbException {
+		long start = now();
+		List<ForumListItem> forums = new ArrayList<>();
+		for (Forum f : forumManager.getForums(txn)) {
+			GroupCount count = forumManager.getGroupCount(txn, f.getId());
+			forums.add(new ForumListItem(f, count));
+		}
+		Collections.sort(forums);
+		logDuration(LOG, "Loading forums", start);
+		return forums;
+	}
+
+	@UiThread
+	private void onForumPostReceived(GroupId g, ForumPostHeader header) {
+		List<ForumListItem> list = updateListItems(forumItems,
+				itemToTest -> itemToTest.getForum().getId().equals(g),
+				itemToUpdate -> new ForumListItem(itemToUpdate, header));
+		if (list == null) return;
+		// re-sort as the order of items may have changed
+		Collections.sort(list);
+		forumItems.setValue(new LiveResult<>(list));
+	}
+
+	@UiThread
+	private void onGroupRemoved(GroupId groupId) {
+		List<ForumListItem> list = removeListItems(forumItems, i ->
+				i.getForum().getId().equals(groupId)
+		);
+		if (list == null) return;
+		forumItems.setValue(new LiveResult<>(list));
+	}
+
+	void loadForumInvitations() {
+		runOnDbThread(() -> {
+			try {
+				long start = now();
+				int available = forumSharingManager.getInvitations().size();
+				logDuration(LOG, "Loading available", start);
+				numInvitations.postValue(available);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+			}
+		});
+	}
+
+	LiveData<LiveResult<List<ForumListItem>>> getForumListItems() {
+		return forumItems;
+	}
+
+	LiveData<Integer> getNumInvitations() {
+		return numInvitations;
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/forum/ForumModule.java

@@ -2,13 +2,25 @@ package org.briarproject.briar.android.forum;
 
 import org.briarproject.briar.android.activity.ActivityScope;
 import org.briarproject.briar.android.activity.BaseActivity;
+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 ForumModule {
 
+	@Module
+	public interface BindsModule {
+		@Binds
+		@IntoMap
+		@ViewModelKey(ForumListViewModel.class)
+		ViewModel bindForumListViewModel(ForumListViewModel forumListViewModel);
+	}
+
 	@ActivityScope
 	@Provides
 	ForumController provideForumController(BaseActivity activity,

briar-android/src/main/java/org/briarproject/briar/android/forum/ForumViewHolder.java

@@ -0,0 +1,77 @@
+package org.briarproject.briar.android.forum;
+
+import android.content.Context;
+import android.content.Intent;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.TextView;
+
+import org.briarproject.briar.R;
+import org.briarproject.briar.android.util.UiUtils;
+import org.briarproject.briar.android.view.TextAvatarView;
+import org.briarproject.briar.api.forum.Forum;
+
+import androidx.recyclerview.widget.RecyclerView;
+
+import static android.view.View.GONE;
+import static android.view.View.VISIBLE;
+import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
+import static org.briarproject.briar.android.activity.BriarActivity.GROUP_NAME;
+
+class ForumViewHolder extends RecyclerView.ViewHolder {
+
+	private final Context ctx;
+	private final ViewGroup layout;
+	private final TextAvatarView avatar;
+	private final TextView name;
+	private final TextView postCount;
+	private final TextView date;
+
+	ForumViewHolder(View v) {
+		super(v);
+		ctx = v.getContext();
+		layout = (ViewGroup) v;
+		avatar = v.findViewById(R.id.avatarView);
+		name = v.findViewById(R.id.forumNameView);
+		postCount = v.findViewById(R.id.postCountView);
+		date = v.findViewById(R.id.dateView);
+	}
+
+	void bind(ForumListItem item) {
+		// Avatar
+		avatar.setText(item.getForum().getName().substring(0, 1));
+		avatar.setBackgroundBytes(item.getForum().getId().getBytes());
+		avatar.setUnreadCount(item.getUnreadCount());
+
+		// Forum Name
+		name.setText(item.getForum().getName());
+
+		// Post Count
+		int count = item.getPostCount();
+		if (count > 0) {
+			postCount.setText(ctx.getResources()
+					.getQuantityString(R.plurals.posts, count, count));
+		} else {
+			postCount.setText(ctx.getString(R.string.no_posts));
+		}
+
+		// Date
+		if (item.isEmpty()) {
+			date.setVisibility(GONE);
+		} else {
+			long timestamp = item.getTimestamp();
+			date.setText(UiUtils.formatDate(ctx, timestamp));
+			date.setVisibility(VISIBLE);
+		}
+
+		// Open Forum on Click
+		layout.setOnClickListener(v -> {
+			Intent i = new Intent(ctx, ForumActivity.class);
+			Forum f = item.getForum();
+			i.putExtra(GROUP_ID, f.getId().getBytes());
+			i.putExtra(GROUP_NAME, f.getName());
+			ctx.startActivity(i);
+		});
+	}
+
+}