Address small things found in code review

of group list view model migration.

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

@@ -152,8 +152,6 @@ public class GroupListFragment extends BaseFragment implements
 	 */
 	@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/GroupListViewModel.java

@@ -5,7 +5,6 @@ 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;
-import org.briarproject.bramble.api.db.NoSuchGroupException;
 import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.db.TransactionManager;
 import org.briarproject.bramble.api.event.Event;
@@ -152,22 +151,18 @@ class GroupListViewModel extends DbViewModel implements EventListener {
 		List<GroupItem> items = new ArrayList<>(groups.size());
 		Map<AuthorId, AuthorInfo> authorInfos = new HashMap<>();
 		for (PrivateGroup g : groups) {
-			try {
+			GroupId id = g.getId();
-				GroupId id = g.getId();
+			AuthorId authorId = g.getCreator().getId();
-				AuthorId authorId = g.getCreator().getId();
+			AuthorInfo authorInfo;
-				AuthorInfo authorInfo;
+			if (authorInfos.containsKey(authorId)) {
-				if (authorInfos.containsKey(authorId)) {
+				authorInfo = requireNonNull(authorInfos.get(authorId));
-					authorInfo = requireNonNull(authorInfos.get(authorId));
+			} else {
-				} else {
+				authorInfo = contactManager.getAuthorInfo(txn, authorId);
-					authorInfo = contactManager.getAuthorInfo(txn, authorId);
+				authorInfos.put(authorId, authorInfo);
-					authorInfos.put(authorId, authorInfo);
-				}
-				GroupCount count = groupManager.getGroupCount(txn, id);
-				boolean dissolved = groupManager.isDissolved(txn, id);
-				items.add(new GroupItem(g, authorInfo, count, dissolved));
-			} catch (NoSuchGroupException e) {
-				// Continue
 			}
+			GroupCount count = groupManager.getGroupCount(txn, id);
+			boolean dissolved = groupManager.isDissolved(txn, id);
+			items.add(new GroupItem(g, authorInfo, count, dissolved));
 		}
 		Collections.sort(items);
 		logDuration(LOG, "Loading groups", start);
@@ -177,7 +172,7 @@ class GroupListViewModel extends DbViewModel implements EventListener {
 	@UiThread
 	private void onGroupMessageAdded(GroupMessageHeader header) {
 		GroupId g = header.getGroupId();
-		List<GroupItem> list = updateListItem(groupItems,
+		List<GroupItem> list = updateListItems(groupItems,
 				itemToTest -> itemToTest.getId().equals(g),
 				itemToUpdate -> new GroupItem(itemToUpdate, header));
 		if (list == null) return;
@@ -188,7 +183,7 @@ class GroupListViewModel extends DbViewModel implements EventListener {
 
 	@UiThread
 	private void onGroupDissolved(GroupId groupId) {
-		List<GroupItem> list = updateListItem(groupItems,
+		List<GroupItem> list = updateListItems(groupItems,
 				itemToTest -> itemToTest.getId().equals(groupId),
 				itemToUpdate -> new GroupItem(itemToUpdate, true));
 		if (list == null) return;
@@ -198,7 +193,7 @@ class GroupListViewModel extends DbViewModel implements EventListener {
 	@UiThread
 	private void onGroupRemoved(GroupId groupId) {
 		List<GroupItem> list =
-				removeListItem(groupItems, i -> i.getId().equals(groupId));
+				removeListItems(groupItems, i -> i.getId().equals(groupId));
 		if (list == null) return;
 		groupItems.setValue(new LiveResult<>(list));
 	}

briar-android/src/main/java/org/briarproject/briar/android/viewmodel/DbViewModel.java

@@ -62,7 +62,7 @@ public abstract class DbViewModel extends AndroidViewModel {
 	 * <p>
 	 * If you need a list of items to be displayed in a
 	 * {@link RecyclerView.Adapter},
-	 * use {@link #loadList(DbCallable, UiCallable)} instead.
+	 * use {@link #loadList(DbCallable, UiConsumer)} instead.
 	 */
 	protected void runOnDbThread(Runnable task) {
 		dbExecutor.execute(() -> {
@@ -92,13 +92,13 @@ public abstract class DbViewModel extends AndroidViewModel {
 	 */
 	protected <T extends List<?>> void loadList(
 			DbCallable<T, DbException> task,
-			UiCallable<LiveResult<T>> uiUpdate) {
+			UiConsumer<LiveResult<T>> uiConsumer) {
 		dbExecutor.execute(() -> {
 			try {
 				lifecycleManager.waitForDatabase();
 				db.transaction(true, txn -> {
 					T t = task.call(txn);
-					txn.attach(() -> uiUpdate.call(new LiveResult<>(t)));
+					txn.attach(() -> uiConsumer.accept(new LiveResult<>(t)));
 				});
 			} catch (InterruptedException e) {
 				LOG.warning("Interrupted while waiting for database");
@@ -106,15 +106,15 @@ public abstract class DbViewModel extends AndroidViewModel {
 			} catch (DbException e) {
 				logException(LOG, WARNING, e);
 				androidExecutor.runOnUiThread(
-						() -> uiUpdate.call(new LiveResult<>(e)));
+						() -> uiConsumer.accept(new LiveResult<>(e)));
 			}
 		});
 	}
 
 	@NotNullByDefault
-	public interface UiCallable<T> {
+	public interface UiConsumer<T> {
 		@UiThread
-		void call(T t);
+		void accept(T t);
 	}
 
 	/**
@@ -130,10 +130,10 @@ public abstract class DbViewModel extends AndroidViewModel {
 	 * </ul>
 	 */
 	@Nullable
-	protected <T> List<T> updateListItem(
+	protected <T> List<T> updateListItems(
 			LiveData<LiveResult<List<T>>> liveData, Function<T, Boolean> test,
 			Function<T, T> replacer) {
-		List<T> items = getList(liveData);
+		List<T> items = getListCopy(liveData);
 		if (items == null) return null;
 
 		ListIterator<T> iterator = items.listIterator();
@@ -161,9 +161,9 @@ public abstract class DbViewModel extends AndroidViewModel {
 	 * </ul>
 	 */
 	@Nullable
-	protected <T> List<T> removeListItem(
+	protected <T> List<T> removeListItems(
 			LiveData<LiveResult<List<T>>> liveData, Function<T, Boolean> test) {
-		List<T> items = getList(liveData);
+		List<T> items = getListCopy(liveData);
 		if (items == null) return null;
 
 		ListIterator<T> iterator = items.listIterator();
@@ -179,11 +179,12 @@ public abstract class DbViewModel extends AndroidViewModel {
 	}
 
 	/**
-	 * Retrieves the list of items from the given LiveData
+	 * Retrieves a copy of the list of items from the given LiveData
 	 * or null if it is not available.
+	 * The list copy can be safely mutated.
 	 */
 	@Nullable
-	private <T> List<T> getList(LiveData<LiveResult<List<T>>> liveData) {
+	private <T> List<T> getListCopy(LiveData<LiveResult<List<T>>> liveData) {
 		LiveResult<List<T>> value = liveData.getValue();
 		if (value == null) return null;
 		List<T> list = value.getResultOrNull();

briar-android/src/test/java/org/briarproject/briar/android/viewmodel/LiveDataTestUtil.java

@@ -7,6 +7,7 @@ package org.briarproject.briar.android.viewmodel;
 
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicReference;
 
 import androidx.annotation.Nullable;
 import androidx.lifecycle.LiveData;
@@ -15,12 +16,12 @@ import androidx.lifecycle.Observer;
 public class LiveDataTestUtil {
 	public static <T> T getOrAwaitValue(final LiveData<T> liveData)
 			throws InterruptedException {
-		final Object[] data = new Object[1];
+		final AtomicReference<T> data = new AtomicReference<>();
 		final CountDownLatch latch = new CountDownLatch(1);
 		Observer<T> observer = new Observer<T>() {
 			@Override
 			public void onChanged(@Nullable T o) {
-				data[0] = o;
+				data.set(o);
 				latch.countDown();
 				liveData.removeObserver(this);
 			}
@@ -30,7 +31,6 @@ public class LiveDataTestUtil {
 		if (!latch.await(2, TimeUnit.SECONDS)) {
 			throw new RuntimeException("LiveData value was never set.");
 		}
-		//noinspection unchecked
+		return data.get();
-		return (T) data[0];
 	}
 }