Reorganize Episode Fragments lifecycle

This uses the existing android lifecycle methods to avoid having to do
null checks and state saving in various places.

3 files changed, 80 insertions, 147 deletions

diff --git a/app/src/main/java/de/danoeh/antennapod/fragment/AllEpisodesFragment.java b/app/src/main/java/de/danoeh/antennapod/fragment/AllEpisodesFragment.java
index 8c9eda146..922e7d321 100644
--- a/app/src/main/java/de/danoeh/antennapod/fragment/AllEpisodesFragment.java
+++ b/app/src/main/java/de/danoeh/antennapod/fragment/AllEpisodesFragment.java
@@ -29,6 +29,7 @@ import org.greenrobot.eventbus.EventBus;
 import org.greenrobot.eventbus.Subscribe;
 import org.greenrobot.eventbus.ThreadMode;
 
+import java.util.ArrayList;
 import java.util.List;
 
 import de.danoeh.antennapod.R;
@@ -43,6 +44,7 @@ import de.danoeh.antennapod.core.feed.Feed;
 import de.danoeh.antennapod.core.feed.FeedItem;
 import de.danoeh.antennapod.core.feed.FeedMedia;
 import de.danoeh.antennapod.core.preferences.UserPreferences;
+import de.danoeh.antennapod.core.service.download.DownloadRequest;
 import de.danoeh.antennapod.core.service.download.DownloadService;
 import de.danoeh.antennapod.core.service.download.Downloader;
 import de.danoeh.antennapod.core.storage.DBReader;
@@ -80,11 +82,10 @@ public class AllEpisodesFragment extends Fragment {
     private ProgressBar progLoading;
     EmptyViewHandler emptyView;
 
-    List<FeedItem> episodes;
-    private List<Downloader> downloaderList;
-
-    private boolean itemsLoaded = false;
-    private boolean viewsCreated = false;
+    @NonNull
+    List<FeedItem> episodes = new ArrayList<>();
+    @NonNull
+    private List<Downloader> downloaderList = new ArrayList<>();
 
     private boolean isUpdatingFeeds;
     boolean isMenuInvalidationAllowed = false;
@@ -101,25 +102,17 @@ public class AllEpisodesFragment extends Fragment {
     }
 
     @Override
-    public void onCreate(Bundle savedInstanceState) {
-        super.onCreate(savedInstanceState);
-        setHasOptionsMenu(true);
-    }
-
-    @Override
     public void onStart() {
         super.onStart();
+        setHasOptionsMenu(true);
         EventDistributor.getInstance().register(contentUpdate);
-        if (viewsCreated && itemsLoaded) {
-            onFragmentLoaded();
-        }
         EventBus.getDefault().register(this);
+        loadItems();
     }
 
     @Override
     public void onResume() {
         super.onResume();
-        loadItems();
         registerForContextMenu(recyclerView);
     }
 
@@ -140,12 +133,6 @@ public class AllEpisodesFragment extends Fragment {
         }
     }
 
-    @Override
-    public void onDestroyView() {
-        super.onDestroyView();
-        resetViewState();
-    }
-
     private void saveScrollPosition() {
         int firstItem = layoutManager.findFirstVisibleItemPosition();
         View firstItemView = layoutManager.findViewByPosition(firstItem);
@@ -177,12 +164,6 @@ public class AllEpisodesFragment extends Fragment {
         }
     }
 
-    void resetViewState() {
-        viewsCreated = false;
-        listAdapter = null;
-    }
-
-
     private final MenuItemUtils.UpdateRefreshMenuItemChecker updateRefreshMenuItemChecker =
             () -> DownloadService.isRunning && DownloadRequester.getInstance().isDownloadingFeeds();
 
@@ -192,28 +173,26 @@ public class AllEpisodesFragment extends Fragment {
             return;
         }
         super.onCreateOptionsMenu(menu, inflater);
-        if (itemsLoaded) {
-            inflater.inflate(R.menu.episodes, menu);
-
-            MenuItem searchItem = menu.findItem(R.id.action_search);
-            final SearchView sv = (SearchView) MenuItemCompat.getActionView(searchItem);
-            MenuItemUtils.adjustTextColor(getActivity(), sv);
-            sv.setQueryHint(getString(R.string.search_hint));
-            sv.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
-                @Override
-                public boolean onQueryTextSubmit(String s) {
-                    sv.clearFocus();
-                    ((MainActivity) getActivity()).loadChildFragment(SearchFragment.newInstance(s));
-                    return true;
-                }
+        inflater.inflate(R.menu.episodes, menu);
+
+        MenuItem searchItem = menu.findItem(R.id.action_search);
+        final SearchView sv = (SearchView) MenuItemCompat.getActionView(searchItem);
+        MenuItemUtils.adjustTextColor(getActivity(), sv);
+        sv.setQueryHint(getString(R.string.search_hint));
+        sv.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
+            @Override
+            public boolean onQueryTextSubmit(String s) {
+                sv.clearFocus();
+                ((MainActivity) requireActivity()).loadChildFragment(SearchFragment.newInstance(s));
+                return true;
+            }
 
-                @Override
-                public boolean onQueryTextChange(String s) {
-                    return false;
-                }
-            });
-            isUpdatingFeeds = MenuItemUtils.updateRefreshMenuItem(menu, R.id.refresh_item, updateRefreshMenuItemChecker);
-        }
+            @Override
+            public boolean onQueryTextChange(String s) {
+                return false;
+            }
+        });
+        isUpdatingFeeds = MenuItemUtils.updateRefreshMenuItem(menu, R.id.refresh_item, updateRefreshMenuItemChecker);
     }
 
     @Override
@@ -221,11 +200,11 @@ public class AllEpisodesFragment extends Fragment {
         super.onPrepareOptionsMenu(menu);
         MenuItem markAllRead = menu.findItem(R.id.mark_all_read_item);
         if (markAllRead != null) {
-            markAllRead.setVisible(!showOnlyNewEpisodes() && episodes != null && !episodes.isEmpty());
+            markAllRead.setVisible(!showOnlyNewEpisodes() && !episodes.isEmpty());
         }
         MenuItem markAllSeen = menu.findItem(R.id.mark_all_seen_item);
         if (markAllSeen != null) {
-            markAllSeen.setVisible(showOnlyNewEpisodes() && episodes != null && !episodes.isEmpty());
+            markAllSeen.setVisible(showOnlyNewEpisodes() && !episodes.isEmpty());
         }
     }
 
@@ -286,7 +265,7 @@ public class AllEpisodesFragment extends Fragment {
             return true; // avoids that the position is reset when we need it in the submenu
         }
 
-        if (listAdapter == null || listAdapter.getSelectedItem() == null) {
+        if (listAdapter.getSelectedItem() == null) {
             Log.i(TAG, "Selected item or listAdapter was null, ignoring selection");
             return super.onContextItemSelected(item);
         }
@@ -305,85 +284,74 @@ public class AllEpisodesFragment extends Fragment {
         return FeedItemMenuHandler.onMenuItemClicked(getActivity(), item.getItemId(), selectedItem);
     }
 
+    @NonNull
     @Override
-    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
-        return onCreateViewHelper(inflater, container, savedInstanceState,
-                R.layout.all_episodes_fragment);
-    }
-
-    View onCreateViewHelper(LayoutInflater inflater,
-                            ViewGroup container,
-                            Bundle savedInstanceState,
-                            int fragmentResource) {
+    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
         super.onCreateView(inflater, container, savedInstanceState);
+        View root = inflater.inflate(R.layout.all_episodes_fragment, container, false);
 
-        View root = inflater.inflate(fragmentResource, container, false);
-
-        recyclerView = root.findViewById(android.R.id.list);
-        RecyclerView.ItemAnimator animator = recyclerView.getItemAnimator();
-        if (animator instanceof SimpleItemAnimator) {
-            ((SimpleItemAnimator) animator).setSupportsChangeAnimations(false);
-        }
         layoutManager = new LinearLayoutManager(getActivity());
+        recyclerView = root.findViewById(android.R.id.list);
         recyclerView.setLayoutManager(layoutManager);
         recyclerView.setHasFixedSize(true);
         recyclerView.addItemDecoration(new HorizontalDividerItemDecoration.Builder(getActivity()).build());
+        recyclerView.setVisibility(View.GONE);
 
-        progLoading = root.findViewById(R.id.progLoading);
-
-        if (!itemsLoaded) {
-            progLoading.setVisibility(View.VISIBLE);
+        RecyclerView.ItemAnimator animator = recyclerView.getItemAnimator();
+        if (animator instanceof SimpleItemAnimator) {
+            ((SimpleItemAnimator) animator).setSupportsChangeAnimations(false);
         }
 
-        viewsCreated = true;
-
-        if (itemsLoaded) {
-            onFragmentLoaded();
-        }
+        progLoading = root.findViewById(R.id.progLoading);
+        progLoading.setVisibility(View.VISIBLE);
 
         emptyView = new EmptyViewHandler(getContext());
         emptyView.attachToRecyclerView(recyclerView);
         emptyView.setTitle(R.string.no_all_episodes_head_label);
         emptyView.setMessage(R.string.no_all_episodes_label);
+        emptyView.hide();
+
+        createRecycleAdapter();
 
         return root;
     }
 
     private void onFragmentLoaded() {
-        if (episodes != null && episodes.size() > 0) {
-            if (listAdapter == null) {
-                MainActivity mainActivity = (MainActivity) getActivity();
-                listAdapter = new AllEpisodesRecycleAdapter(mainActivity, itemAccess, showOnlyNewEpisodes());
-                listAdapter.setHasStableIds(true);
-                recyclerView.setAdapter(listAdapter);
-                emptyView.updateAdapter(listAdapter);
-            }
+        if (episodes.size() > 0) {
             recyclerView.setVisibility(View.VISIBLE);
             listAdapter.notifyDataSetChanged();
         } else {
-            listAdapter = null;
+            createRecycleAdapter();
             recyclerView.setVisibility(View.GONE);
             emptyView.updateAdapter(listAdapter);
         }
 
         restoreScrollPosition();
-        getActivity().supportInvalidateOptionsMenu();
-        updateShowOnlyEpisodesListViewState();
+        requireActivity().invalidateOptionsMenu();
+    }
+
+    /**
+     * Currently, we need to recreate the list adapter in order to be able to undo last item via the
+     * snackbar. See #3084 for details.
+     */
+    private void createRecycleAdapter() {
+        MainActivity mainActivity = (MainActivity) getActivity();
+        listAdapter = new AllEpisodesRecycleAdapter(mainActivity, itemAccess, showOnlyNewEpisodes());
+        listAdapter.setHasStableIds(true);
+        recyclerView.setAdapter(listAdapter);
+        emptyView.updateAdapter(listAdapter);
     }
 
     private final AllEpisodesRecycleAdapter.ItemAccess itemAccess = new AllEpisodesRecycleAdapter.ItemAccess() {
 
         @Override
         public int getCount() {
-            if (episodes != null) {
-                return episodes.size();
-            }
-            return 0;
+            return episodes.size();
         }
 
         @Override
         public FeedItem getItem(int position) {
-            if (episodes != null && 0 <= position && position < episodes.size()) {
+            if (0 <= position && position < episodes.size()) {
                 return episodes.get(position);
             }
             return null;
@@ -391,9 +359,6 @@ public class AllEpisodesFragment extends Fragment {
 
         @Override
         public LongList getItemsIds() {
-            if (episodes == null) {
-                return new LongList(0);
-            }
             LongList ids = new LongList(episodes.size());
             for (FeedItem episode : episodes) {
                 ids.add(episode.getId());
@@ -403,12 +368,11 @@ public class AllEpisodesFragment extends Fragment {
 
         @Override
         public int getItemDownloadProgressPercent(FeedItem item) {
-            if (downloaderList != null) {
-                for (Downloader downloader : downloaderList) {
-                    if (downloader.getDownloadRequest().getFeedfileType() == FeedMedia.FEEDFILETYPE_FEEDMEDIA
-                            && downloader.getDownloadRequest().getFeedfileId() == item.getMedia().getId()) {
-                        return downloader.getDownloadRequest().getProgressPercent();
-                    }
+            for (Downloader downloader : downloaderList) {
+                DownloadRequest downloadRequest = downloader.getDownloadRequest();
+                if (downloadRequest.getFeedfileType() == FeedMedia.FEEDFILETYPE_FEEDMEDIA
+                        && downloadRequest.getFeedfileId() == item.getMedia().getId()) {
+                    return downloadRequest.getProgressPercent();
                 }
             }
             return 0;
@@ -422,9 +386,6 @@ public class AllEpisodesFragment extends Fragment {
         @Override
         public LongList getQueueIds() {
             LongList queueIds = new LongList();
-            if (episodes == null) {
-                return queueIds;
-            }
             for (FeedItem item : episodes) {
                 if (item.isTagged(FeedItem.TAG_QUEUE)) {
                     queueIds.add(item.getId());
@@ -438,12 +399,6 @@ public class AllEpisodesFragment extends Fragment {
     @Subscribe(threadMode = ThreadMode.MAIN)
     public void onEventMainThread(FeedItemEvent event) {
         Log.d(TAG, "onEventMainThread() called with: " + "event = [" + event + "]");
-        if (episodes == null) {
-            return;
-        } else if (listAdapter == null) {
-            loadItems();
-            return;
-        }
         for (FeedItem item : event.items) {
             int pos = FeedItemUtil.indexOfItemWithId(episodes, item.getId());
             if (pos >= 0) {
@@ -468,11 +423,7 @@ public class AllEpisodesFragment extends Fragment {
         DownloaderUpdate update = event.update;
         downloaderList = update.downloaders;
         if (isMenuInvalidationAllowed && isUpdatingFeeds != update.feedIds.length > 0) {
-            getActivity().supportInvalidateOptionsMenu();
-        }
-        if (listAdapter == null) {
-            loadItems();
-            return;
+            requireActivity().invalidateOptionsMenu();
         }
         if (update.mediaIds.length > 0) {
             for (long mediaId : update.mediaIds) {
@@ -490,24 +441,16 @@ public class AllEpisodesFragment extends Fragment {
             if ((arg & EVENTS) != 0) {
                 loadItems();
                 if (isUpdatingFeeds != updateRefreshMenuItemChecker.isRefreshing()) {
-                    getActivity().supportInvalidateOptionsMenu();
+                    requireActivity().invalidateOptionsMenu();
                 }
             }
         }
     };
 
-    private void updateShowOnlyEpisodesListViewState() {
-    }
-
     void loadItems() {
         if (disposable != null) {
             disposable.dispose();
         }
-        if (viewsCreated && !itemsLoaded) {
-            recyclerView.setVisibility(View.GONE);
-            emptyView.hide();
-            progLoading.setVisibility(View.VISIBLE);
-        }
         disposable = Observable.fromCallable(this::loadData)
                 .subscribeOn(Schedulers.io())
                 .observeOn(AndroidSchedulers.mainThread())
@@ -515,10 +458,7 @@ public class AllEpisodesFragment extends Fragment {
                     recyclerView.setVisibility(View.VISIBLE);
                     progLoading.setVisibility(View.GONE);
                     episodes = data;
-                    itemsLoaded = true;
-                    if (viewsCreated) {
-                        onFragmentLoaded();
-                    }
+                    onFragmentLoaded();
                 }, error -> Log.e(TAG, Log.getStackTraceString(error)));
     }
 
diff --git a/app/src/main/java/de/danoeh/antennapod/fragment/FavoriteEpisodesFragment.java b/app/src/main/java/de/danoeh/antennapod/fragment/FavoriteEpisodesFragment.java
index b2feb222f..c273a7033 100644
--- a/app/src/main/java/de/danoeh/antennapod/fragment/FavoriteEpisodesFragment.java
+++ b/app/src/main/java/de/danoeh/antennapod/fragment/FavoriteEpisodesFragment.java
@@ -1,6 +1,7 @@
 package de.danoeh.antennapod.fragment;
 
 import android.os.Bundle;
+import android.support.annotation.NonNull;
 import android.support.design.widget.Snackbar;
 import android.support.v7.widget.RecyclerView;
 import android.support.v7.widget.helper.ItemTouchHelper;
@@ -27,7 +28,6 @@ import de.danoeh.antennapod.core.storage.DBWriter;
 public class FavoriteEpisodesFragment extends AllEpisodesFragment {
 
     private static final String TAG = "FavoriteEpisodesFrag";
-
     private static final String PREF_NAME = "PrefFavoriteEpisodesFragment";
 
     @Override
@@ -42,19 +42,14 @@ public class FavoriteEpisodesFragment extends AllEpisodesFragment {
 
     @Subscribe
     public void onEvent(FavoritesEvent event) {
-        Log.d(TAG, "onEvent() called with: " + "event = [" + event + "]");
+        Log.d(TAG, String.format("onEvent() called with: event = [%s]", event));
         loadItems();
     }
 
+    @NonNull
     @Override
-    protected void resetViewState() {
-        super.resetViewState();
-    }
-
-    @Override
-    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
-        View root = super.onCreateViewHelper(inflater, container, savedInstanceState,
-                R.layout.all_episodes_fragment);
+    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
+        View root = super.onCreateView(inflater, container, savedInstanceState);
         emptyView.setTitle(R.string.no_fav_episodes_head_label);
         emptyView.setMessage(R.string.no_fav_episodes_label);
 
@@ -67,7 +62,7 @@ public class FavoriteEpisodesFragment extends AllEpisodesFragment {
             @Override
             public void onSwiped(RecyclerView.ViewHolder viewHolder, int swipeDir) {
                 AllEpisodesRecycleAdapter.Holder holder = (AllEpisodesRecycleAdapter.Holder) viewHolder;
-                Log.d(TAG, "remove(" + holder.getItemId() + ")");
+                Log.d(TAG, String.format("remove(%s)", holder.getItemId()));
 
                 if (disposable != null) {
                     disposable.dispose();
@@ -88,6 +83,7 @@ public class FavoriteEpisodesFragment extends AllEpisodesFragment {
         return root;
     }
 
+    @NonNull
     @Override
     protected List<FeedItem> loadData() {
         return DBReader.getFavoriteItemsList();
diff --git a/app/src/main/java/de/danoeh/antennapod/fragment/NewEpisodesFragment.java b/app/src/main/java/de/danoeh/antennapod/fragment/NewEpisodesFragment.java
index f973cdadb..6da68d369 100644
--- a/app/src/main/java/de/danoeh/antennapod/fragment/NewEpisodesFragment.java
+++ b/app/src/main/java/de/danoeh/antennapod/fragment/NewEpisodesFragment.java
@@ -1,6 +1,7 @@
 package de.danoeh.antennapod.fragment;
 
 import android.os.Bundle;
+import android.support.annotation.NonNull;
 import android.support.v7.widget.RecyclerView;
 import android.support.v7.widget.helper.ItemTouchHelper;
 import android.view.LayoutInflater;
@@ -34,19 +35,14 @@ public class NewEpisodesFragment extends AllEpisodesFragment {
     }
 
     @Override
-    protected void resetViewState() {
-        super.resetViewState();
-    }
-
-    @Override
     protected boolean shouldUpdatedItemRemainInList(FeedItem item) {
         return item.isNew();
     }
 
+    @NonNull
     @Override
-    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
-        View root = super.onCreateViewHelper(inflater, container, savedInstanceState,
-                R.layout.all_episodes_fragment);
+    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
+        View root = super.onCreateView(inflater, container, savedInstanceState);
         emptyView.setTitle(R.string.no_new_episodes_head_label);
         emptyView.setMessage(R.string.no_new_episodes_label);
 
@@ -96,6 +92,7 @@ public class NewEpisodesFragment extends AllEpisodesFragment {
         return root;
     }
 
+    @NonNull
     @Override
     protected List<FeedItem> loadData() {
         return DBReader.getNewItemsList();