Genres tab

app/src/main/AndroidManifest.xml

@@ -94,6 +94,7 @@
         </activity>
         <activity android:name=".ui.activities.AlbumDetailActivity" />
         <activity android:name=".ui.activities.ArtistDetailActivity" />
+        <activity android:name=".ui.activities.GenreDetailActivity" />
         <activity android:name=".ui.activities.PlaylistDetailActivity" />
         <activity
             android:name=".ui.activities.tageditor.SongTagEditorActivity"

app/src/main/java/com/kabouzeid/gramophone/adapter/GenreAdapter.java

@@ -0,0 +1,88 @@
+package com.kabouzeid.gramophone.adapter;
+
+import android.support.annotation.LayoutRes;
+import android.support.annotation.NonNull;
+import android.support.v7.app.AppCompatActivity;
+import android.support.v7.widget.RecyclerView;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+
+import com.kabouzeid.gramophone.adapter.base.MediaEntryViewHolder;
+import com.kabouzeid.gramophone.model.Genre;
+import com.kabouzeid.gramophone.util.MusicUtil;
+import com.kabouzeid.gramophone.util.NavigationUtil;
+import com.simplecityapps.recyclerview_fastscroll.views.FastScrollRecyclerView;
+
+import java.util.ArrayList;
+
+public class GenreAdapter extends RecyclerView.Adapter<GenreAdapter.ViewHolder> implements FastScrollRecyclerView.SectionedAdapter {
+
+    public static final String TAG = GenreAdapter.class.getSimpleName();
+
+    @NonNull
+    private final AppCompatActivity activity;
+    private ArrayList<Genre> dataSet;
+    private int itemLayoutRes;
+
+    public GenreAdapter(@NonNull AppCompatActivity activity, ArrayList<Genre> dataSet, @LayoutRes int itemLayoutRes) {
+        this.activity = activity;
+        this.dataSet = dataSet;
+        this.itemLayoutRes = itemLayoutRes;
+    }
+
+    public ArrayList<Genre> getDataSet() {
+        return dataSet;
+    }
+
+    public void swapDataSet(ArrayList<Genre> dataSet) {
+        this.dataSet = dataSet;
+        notifyDataSetChanged();
+    }
+
+    @Override
+    public long getItemId(int position) {
+        return dataSet.get(position).hashCode();
+    }
+
+    @NonNull
+    @Override
+    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
+        View view = LayoutInflater.from(activity).inflate(itemLayoutRes, parent, false);
+        return new ViewHolder(view);
+    }
+
+    @Override
+    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
+        final Genre genre = dataSet.get(position);
+
+        if (holder.title != null) {
+            holder.title.setText(genre.name);
+        }
+    }
+
+    @Override
+    public int getItemCount() {
+        return dataSet.size();
+    }
+
+    @NonNull
+    @Override
+    public String getSectionName(int position) {
+        final Genre genre = dataSet.get(position);
+        return genre.id == -1 ? "" : MusicUtil.getSectionName(dataSet.get(position).name);
+    }
+
+    public class ViewHolder extends MediaEntryViewHolder {
+
+        public ViewHolder(@NonNull View itemView) {
+            super(itemView);
+        }
+
+        @Override
+        public void onClick(View view) {
+            Genre genre = dataSet.get(getAdapterPosition());
+            NavigationUtil.goToGenre(activity, genre);
+        }
+    }
+}

app/src/main/java/com/kabouzeid/gramophone/adapter/MusicLibraryPagerAdapter.java

@@ -12,6 +12,7 @@ import android.view.ViewGroup;
 import com.kabouzeid.gramophone.R;
 import com.kabouzeid.gramophone.ui.fragments.mainactivity.library.pager.AlbumsFragment;
 import com.kabouzeid.gramophone.ui.fragments.mainactivity.library.pager.ArtistsFragment;
+import com.kabouzeid.gramophone.ui.fragments.mainactivity.library.pager.GenresFragment;
 import com.kabouzeid.gramophone.ui.fragments.mainactivity.library.pager.PlaylistsFragment;
 import com.kabouzeid.gramophone.ui.fragments.mainactivity.library.pager.SongsFragment;
 
@@ -39,6 +40,7 @@ public class MusicLibraryPagerAdapter extends FragmentPagerAdapter {
                 context.getResources().getString(R.string.songs),
                 context.getResources().getString(R.string.albums),
                 context.getResources().getString(R.string.artists),
+                context.getResources().getString(R.string.genres),
                 context.getResources().getString(R.string.playlists)
         };
         final MusicFragments[] fragments = MusicFragments.values();
@@ -110,6 +112,7 @@ public class MusicLibraryPagerAdapter extends FragmentPagerAdapter {
         SONG(SongsFragment.class),
         ALBUM(AlbumsFragment.class),
         ARTIST(ArtistsFragment.class),
+        GENRES(GenresFragment.class),
         PLAYLIST(PlaylistsFragment.class);
 
         private final Class<? extends Fragment> mFragmentClass;
@@ -121,12 +124,10 @@ public class MusicLibraryPagerAdapter extends FragmentPagerAdapter {
         public Class<? extends Fragment> getFragmentClass() {
             return mFragmentClass;
         }
-
     }
 
     private final static class Holder {
         String mClassName;
-
         Bundle mParams;
     }
 }

app/src/main/java/com/kabouzeid/gramophone/helper/SortOrder.java

@@ -153,4 +153,15 @@ public final class SortOrder {
                 + " ASC";
     }
 
+    /**
+     * Genre sort order entries.
+     */
+    public interface GenreSortOrder {
+        /* Genre sort order A-Z */
+        String GENRE_A_Z = MediaStore.Audio.Genres.DEFAULT_SORT_ORDER;
+
+        /* Genre sort order Z-A */
+        String ALBUM_Z_A = GENRE_A_Z + " DESC";
+    }
+
 }

app/src/main/java/com/kabouzeid/gramophone/interfaces/LoaderIds.java

@@ -7,10 +7,12 @@ public interface LoaderIds {
     int ALBUM_DETAIL_ACTIVITY = 1;
     int ARTIST_DETAIL_ACTIVITY = 2;
     int PLAYLIST_DETAIL_ACTIVITY = 3;
-    int SEARCH_ACTIVITY = 4;
+    int GENRE_DETAIL_ACTIVITY = 4;
-    int FOLDERS_FRAGMENT = 5;
+    int SEARCH_ACTIVITY = 5;
-    int ALBUMS_FRAGMENT = 6;
+    int FOLDERS_FRAGMENT = 6;
-    int ARTISTS_FRAGMENT = 7;
+    int ALBUMS_FRAGMENT = 7;
-    int PLAYLISTS_FRAGMENT = 8;
+    int ARTISTS_FRAGMENT = 8;
-    int SONGS_FRAGMENT = 9;
+    int PLAYLISTS_FRAGMENT = 9;
+    int GENRES_FRAGMENT = 10;
+    int SONGS_FRAGMENT = 11;
 }

app/src/main/java/com/kabouzeid/gramophone/loader/GenreLoader.java

@@ -0,0 +1,129 @@
+package com.kabouzeid.gramophone.loader;
+
+import android.content.Context;
+import android.database.Cursor;
+import android.net.Uri;
+import android.provider.MediaStore.Audio.Genres;
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+
+import com.kabouzeid.gramophone.R;
+import com.kabouzeid.gramophone.model.Genre;
+import com.kabouzeid.gramophone.model.Song;
+import com.kabouzeid.gramophone.util.PreferenceUtil;
+
+import java.util.ArrayList;
+
+public class GenreLoader {
+
+    @NonNull
+    public static ArrayList<Genre> getAllGenres(@NonNull final Context context) {
+        final String[] projection = new String[]{
+                Genres._ID,
+                Genres.NAME
+        };
+        final String selection = Genres._ID + " IN" +
+                " (SELECT " + Genres.Members.GENRE_ID + " FROM audio_genres_map WHERE " + Genres.Members.AUDIO_ID + " IN" +
+                " (SELECT " + Genres._ID + " FROM audio_meta WHERE " + SongLoader.BASE_SELECTION + "))";
+
+        final Cursor cursor = context.getContentResolver().query(
+                Genres.EXTERNAL_CONTENT_URI,
+                projection, selection, null, PreferenceUtil.getInstance(context).getGenreSortOrder());
+
+        return getGenresFromCursor(context, cursor);
+    }
+
+    @NonNull
+    public static ArrayList<Song> getSongs(@NonNull final Context context, final int genreId) {
+        // The genres table only stores songs that have a genre specified,
+        // so we need to get songs without a genre a different way.
+        if (genreId == -1) {
+            return getSongsWithNoGenre(context);
+        }
+
+        final Cursor cursor = context.getContentResolver().query(
+                Genres.Members.getContentUri("external", genreId),
+                SongLoader.BASE_PROJECTION, SongLoader.BASE_SELECTION, null, null);
+
+        return SongLoader.getSongs(cursor);
+    }
+
+    @NonNull
+    private static ArrayList<Genre> getGenresFromCursor(@NonNull final Context context, @Nullable final Cursor cursor) {
+        final ArrayList<Genre> genres = new ArrayList<>();
+
+        if (hasSongsWithNoGenre(context)) {
+            genres.add(new Genre(context.getResources().getString(R.string.unknown_genre)));
+        }
+
+        if (cursor != null) {
+            if (cursor.moveToFirst()) {
+                do {
+                    genres.add(getGenreFromCursor(cursor));
+                } while (cursor.moveToNext());
+            }
+            cursor.close();
+        }
+        return genres;
+    }
+
+    @NonNull
+    private static Genre getGenreFromCursor(@NonNull final Cursor cursor) {
+        final int id = cursor.getInt(0);
+        final String name = cursor.getString(1);
+        return new Genre(id, name);
+    }
+
+    @NonNull
+    private static ArrayList<Song> getSongsWithNoGenre(@NonNull final Context context) {
+        final Cursor cursor = makeAllSongsWithGenreCursor(context);
+        ArrayList<Song> songs = new ArrayList<>();
+        final int[] songIds = getSongIdsFromCursor(cursor);
+        if (songIds.length > 0) {
+            songs = SongLoader.getSongsNotIn(context, songIds);
+        }
+        return songs;
+    }
+
+    private static int[] getSongIdsFromCursor(@Nullable final Cursor cursor) {
+        if (cursor == null) {
+            return new int[]{};
+        }
+
+        int[] songIds = new int[cursor.getCount()];
+        if (cursor.moveToFirst()) {
+            int i = 0;
+            do {
+                songIds[i] = cursor.getInt(0);
+                i++;
+            } while (cursor.moveToNext());
+        }
+        cursor.close();
+        return songIds;
+    }
+
+    private static boolean hasSongsWithNoGenre(@NonNull final Context context) {
+        final Cursor allSongsCursor = SongLoader.makeSongCursor(context, null, null);
+        final Cursor allSongsWithGenreCursor = makeAllSongsWithGenreCursor(context);
+
+        if (allSongsCursor == null || allSongsWithGenreCursor == null) {
+            return false;
+        }
+
+        final boolean hasSongsWithNoGenre = allSongsCursor.getCount() > allSongsWithGenreCursor.getCount();
+        allSongsCursor.close();
+        allSongsWithGenreCursor.close();
+        return hasSongsWithNoGenre;
+    }
+
+    @Nullable
+    private static Cursor makeAllSongsWithGenreCursor(@NonNull final Context context) {
+        try {
+            return context.getContentResolver().query(
+                    Uri.parse("content://media/external/audio/genres/all/members"),
+                    new String[]{Genres.Members.AUDIO_ID}, null, null, null);
+        } catch (SecurityException e) {
+            return null;
+        }
+    }
+}

app/src/main/java/com/kabouzeid/gramophone/loader/SongLoader.java

@@ -12,12 +12,26 @@ import com.kabouzeid.gramophone.model.Song;
 import com.kabouzeid.gramophone.util.PreferenceUtil;
 
 import java.util.ArrayList;
+import java.util.Arrays;
 
 /**
  * @author Karim Abou Zeid (kabouzeid)
  */
 public class SongLoader {
     protected static final String BASE_SELECTION = AudioColumns.IS_MUSIC + "=1" + " AND " + AudioColumns.TITLE + " != ''";
+    protected static final String[] BASE_PROJECTION = new String[]{
+            BaseColumns._ID,             // 0
+            AudioColumns.TITLE,          // 1
+            AudioColumns.TRACK,          // 2
+            AudioColumns.YEAR,           // 3
+            AudioColumns.DURATION,       // 4
+            AudioColumns.DATA,           // 5
+            AudioColumns.DATE_MODIFIED,  // 6
+            AudioColumns.ALBUM_ID,       // 7
+            AudioColumns.ALBUM,          // 8
+            AudioColumns.ARTIST_ID,      // 9
+            AudioColumns.ARTIST,         // 10
+    };
 
     @NonNull
     public static ArrayList<Song> getAllSongs(@NonNull Context context) {
@@ -31,6 +45,13 @@ public class SongLoader {
         return getSongs(cursor);
     }
 
+    @NonNull
+    public static ArrayList<Song> getSongsNotIn(@NonNull final Context context, final int[] query) {
+        final String ids = convertArrayToQueryList(query);
+        Cursor cursor = makeSongCursor(context, AudioColumns._ID + " NOT IN " + ids, null);
+        return getSongs(cursor);
+    }
+
     @NonNull
     public static Song getSong(@NonNull final Context context, final int queryId) {
         Cursor cursor = makeSongCursor(context, AudioColumns._ID + "=?", new String[]{String.valueOf(queryId)});
@@ -96,22 +117,13 @@ public class SongLoader {
 
         try {
             return context.getContentResolver().query(MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,
-                    new String[]{
+                    BASE_PROJECTION, baseSelection, selectionValues, sortOrder);
-                            BaseColumns._ID,// 0
-                            AudioColumns.TITLE,// 1
-                            AudioColumns.TRACK,// 2
-                            AudioColumns.YEAR,// 3
-                            AudioColumns.DURATION,// 4
-                            AudioColumns.DATA,// 5
-                            AudioColumns.DATE_MODIFIED,// 6
-                            AudioColumns.ALBUM_ID,// 7
-                            AudioColumns.ALBUM,// 8
-                            AudioColumns.ARTIST_ID,// 9
-                            AudioColumns.ARTIST,// 10
-
-                    }, baseSelection, selectionValues, sortOrder);
         } catch (SecurityException e) {
             return null;
         }
     }
+
+    private static String convertArrayToQueryList(final int[] array) {
+        return "(" + Arrays.toString(array).replaceAll("\\[|\\]|\\s", "") + ")";
+    }
 }

app/src/main/java/com/kabouzeid/gramophone/model/Genre.java

@@ -0,0 +1,72 @@
+package com.kabouzeid.gramophone.model;
+
+import android.os.Parcel;
+import android.os.Parcelable;
+
+public class Genre implements Parcelable {
+    public final int id;
+    public final String name;
+
+    public Genre(final int id, final String name) {
+        this.id = id;
+        this.name = name;
+    }
+
+    // For unknown genre
+    public Genre(final String name) {
+        this.id = -1;
+        this.name = name;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+
+        Genre genre = (Genre) o;
+
+        if (id != genre.id) return false;
+        return name != null ? name.equals(genre.name) : genre.name == null;
+    }
+
+    @Override
+    public int hashCode() {
+        int result = id;
+        result = 31 * result + (name != null ? name.hashCode() : 0);
+        return result;
+    }
+
+    @Override
+    public String toString() {
+        return "Genre{" +
+                "id=" + id +
+                ", name='" + name + '\'' +
+                '}';
+    }
+
+    @Override
+    public int describeContents() {
+        return 0;
+    }
+
+    @Override
+    public void writeToParcel(Parcel dest, int flags) {
+        dest.writeInt(this.id);
+        dest.writeString(this.name);
+    }
+
+    protected Genre(Parcel in) {
+        this.id = in.readInt();
+        this.name = in.readString();
+    }
+
+    public static final Creator<Genre> CREATOR = new Creator<Genre>() {
+        public Genre createFromParcel(Parcel source) {
+            return new Genre(source);
+        }
+
+        public Genre[] newArray(int size) {
+            return new Genre[size];
+        }
+    };
+}

app/src/main/java/com/kabouzeid/gramophone/ui/activities/GenreDetailActivity.java

@@ -0,0 +1,206 @@
+package com.kabouzeid.gramophone.ui.activities;
+
+import android.content.Context;
+import android.os.Bundle;
+import android.support.annotation.NonNull;
+import android.support.v4.app.LoaderManager;
+import android.support.v4.content.Loader;
+import android.support.v7.widget.LinearLayoutManager;
+import android.support.v7.widget.RecyclerView;
+import android.support.v7.widget.Toolbar;
+import android.view.Menu;
+import android.view.MenuItem;
+import android.view.View;
+import android.widget.TextView;
+
+import com.afollestad.materialcab.MaterialCab;
+import com.h6ah4i.android.widget.advrecyclerview.utils.WrapperAdapterUtils;
+import com.kabouzeid.appthemehelper.ThemeStore;
+import com.kabouzeid.gramophone.R;
+import com.kabouzeid.gramophone.adapter.song.SongAdapter;
+import com.kabouzeid.gramophone.helper.MusicPlayerRemote;
+import com.kabouzeid.gramophone.interfaces.CabHolder;
+import com.kabouzeid.gramophone.interfaces.LoaderIds;
+import com.kabouzeid.gramophone.loader.GenreLoader;
+import com.kabouzeid.gramophone.misc.WrappedAsyncTaskLoader;
+import com.kabouzeid.gramophone.model.Genre;
+import com.kabouzeid.gramophone.model.Song;
+import com.kabouzeid.gramophone.ui.activities.base.AbsSlidingMusicPanelActivity;
+import com.kabouzeid.gramophone.util.PhonographColorUtil;
+import com.kabouzeid.gramophone.util.ViewUtil;
+import com.simplecityapps.recyclerview_fastscroll.views.FastScrollRecyclerView;
+
+import java.util.ArrayList;
+
+import butterknife.BindView;
+import butterknife.ButterKnife;
+
+public class GenreDetailActivity extends AbsSlidingMusicPanelActivity implements CabHolder, LoaderManager.LoaderCallbacks<ArrayList<Song>> {
+
+    public static final String TAG = GenreDetailActivity.class.getSimpleName();
+    private static final int LOADER_ID = LoaderIds.GENRE_DETAIL_ACTIVITY;
+
+    public static final String EXTRA_GENRE = "extra_genre";
+
+    @BindView(R.id.recycler_view)
+    RecyclerView recyclerView;
+    @BindView(R.id.toolbar)
+    Toolbar toolbar;
+    @BindView(android.R.id.empty)
+    TextView empty;
+
+    private Genre genre;
+
+    private MaterialCab cab;
+    private SongAdapter adapter;
+
+    private RecyclerView.Adapter wrappedAdapter;
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setDrawUnderStatusbar(true);
+        ButterKnife.bind(this);
+
+        setStatusbarColorAuto();
+        setNavigationbarColorAuto();
+        setTaskDescriptionColorAuto();
+
+        genre = getIntent().getExtras().getParcelable(EXTRA_GENRE);
+
+        setUpRecyclerView();
+
+        setUpToolBar();
+
+        getSupportLoaderManager().initLoader(LOADER_ID, null, this);
+    }
+
+    @Override
+    protected View createContentView() {
+        return wrapSlidingMusicPanel(R.layout.activity_genre_detail);
+    }
+
+    private void setUpRecyclerView() {
+        ViewUtil.setUpFastScrollRecyclerViewColor(this, ((FastScrollRecyclerView) recyclerView), ThemeStore.accentColor(this));
+        recyclerView.setLayoutManager(new LinearLayoutManager(this));
+
+        adapter = new SongAdapter(this, new ArrayList<Song>(), R.layout.item_list, false, this);
+        recyclerView.setAdapter(adapter);
+
+        adapter.registerAdapterDataObserver(new RecyclerView.AdapterDataObserver() {
+            @Override
+            public void onChanged() {
+                super.onChanged();
+                checkIsEmpty();
+            }
+        });
+    }
+
+    private void setUpToolBar() {
+        toolbar.setBackgroundColor(ThemeStore.primaryColor(this));
+        setSupportActionBar(toolbar);
+        //noinspection ConstantConditions
+        getSupportActionBar().setTitle(genre.name);
+        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
+    }
+
+    @Override
+    public boolean onCreateOptionsMenu(Menu menu) {
+        getMenuInflater().inflate(R.menu.menu_genre_detail, menu);
+        return super.onCreateOptionsMenu(menu);
+    }
+
+    @Override
+    public boolean onOptionsItemSelected(@NonNull MenuItem item) {
+        int id = item.getItemId();
+        switch (id) {
+            case R.id.action_shuffle_genre:
+                MusicPlayerRemote.openAndShuffleQueue(adapter.getDataSet(), true);
+                return true;
+            case android.R.id.home:
+                onBackPressed();
+                return true;
+        }
+        return super.onOptionsItemSelected(item);
+    }
+
+    @NonNull
+    @Override
+    public MaterialCab openCab(final int menu, final MaterialCab.Callback callback) {
+        if (cab != null && cab.isActive()) cab.finish();
+        cab = new MaterialCab(this, R.id.cab_stub)
+                .setMenu(menu)
+                .setCloseDrawableRes(R.drawable.ic_close_white_24dp)
+                .setBackgroundColor(PhonographColorUtil.shiftBackgroundColorForLightText(ThemeStore.primaryColor(this)))
+                .start(callback);
+        return cab;
+    }
+
+    @Override
+    public void onBackPressed() {
+        if (cab != null && cab.isActive()) cab.finish();
+        else {
+            recyclerView.stopScroll();
+            super.onBackPressed();
+        }
+    }
+
+    @Override
+    public void onMediaStoreChanged() {
+        super.onMediaStoreChanged();
+        getSupportLoaderManager().restartLoader(LOADER_ID, null, this);
+    }
+
+    private void checkIsEmpty() {
+        empty.setVisibility(
+                adapter.getItemCount() == 0 ? View.VISIBLE : View.GONE
+        );
+    }
+
+    @Override
+    protected void onDestroy() {
+        if (recyclerView != null) {
+            recyclerView.setAdapter(null);
+            recyclerView = null;
+        }
+
+        if (wrappedAdapter != null) {
+            WrapperAdapterUtils.releaseAll(wrappedAdapter);
+            wrappedAdapter = null;
+        }
+        adapter = null;
+
+        super.onDestroy();
+    }
+
+    @Override
+    public Loader<ArrayList<Song>> onCreateLoader(int id, Bundle args) {
+        return new GenreDetailActivity.AsyncGenreSongLoader(this, genre);
+    }
+
+    @Override
+    public void onLoadFinished(Loader<ArrayList<Song>> loader, ArrayList<Song> data) {
+        if (adapter != null)
+            adapter.swapDataSet(data);
+    }
+
+    @Override
+    public void onLoaderReset(Loader<ArrayList<Song>> loader) {
+        if (adapter != null)
+            adapter.swapDataSet(new ArrayList<Song>());
+    }
+
+    private static class AsyncGenreSongLoader extends WrappedAsyncTaskLoader<ArrayList<Song>> {
+        private final Genre genre;
+
+        public AsyncGenreSongLoader(Context context, Genre genre) {
+            super(context);
+            this.genre = genre;
+        }
+
+        @Override
+        public ArrayList<Song> loadInBackground() {
+            return GenreLoader.getSongs(getContext(), genre.id);
+        }
+    }
+}

app/src/main/java/com/kabouzeid/gramophone/ui/fragments/mainactivity/library/pager/GenresFragment.java

@@ -0,0 +1,79 @@
+package com.kabouzeid.gramophone.ui.fragments.mainactivity.library.pager;
+
+import android.content.Context;
+import android.os.Bundle;
+import android.support.annotation.NonNull;
+import android.support.v4.app.LoaderManager;
+import android.support.v4.content.Loader;
+import android.support.v7.widget.LinearLayoutManager;
+
+import com.kabouzeid.gramophone.R;
+import com.kabouzeid.gramophone.adapter.GenreAdapter;
+import com.kabouzeid.gramophone.interfaces.LoaderIds;
+import com.kabouzeid.gramophone.loader.GenreLoader;
+import com.kabouzeid.gramophone.misc.WrappedAsyncTaskLoader;
+import com.kabouzeid.gramophone.model.Genre;
+
+import java.util.ArrayList;
+
+public class GenresFragment extends AbsLibraryPagerRecyclerViewFragment<GenreAdapter, LinearLayoutManager> implements LoaderManager.LoaderCallbacks<ArrayList<Genre>> {
+
+    public static final String TAG = GenresFragment.class.getSimpleName();
+
+    private static final int LOADER_ID = LoaderIds.GENRES_FRAGMENT;
+
+    @Override
+    public void onActivityCreated(Bundle savedInstanceState) {
+        super.onActivityCreated(savedInstanceState);
+        getLoaderManager().initLoader(LOADER_ID, null, this);
+    }
+
+    @NonNull
+    @Override
+    protected LinearLayoutManager createLayoutManager() {
+        return new LinearLayoutManager(getActivity());
+    }
+
+    @NonNull
+    @Override
+    protected GenreAdapter createAdapter() {
+        ArrayList<Genre> dataSet = getAdapter() == null ? new ArrayList<Genre>() : getAdapter().getDataSet();
+        return new GenreAdapter(getLibraryFragment().getMainActivity(), dataSet, R.layout.item_list_simple);
+    }
+
+    @Override
+    protected int getEmptyMessage() {
+        return R.string.no_genres;
+    }
+
+    @Override
+    public void onMediaStoreChanged() {
+        getLoaderManager().restartLoader(LOADER_ID, null, this);
+    }
+
+    @Override
+    public Loader<ArrayList<Genre>> onCreateLoader(int id, Bundle args) {
+        return new GenresFragment.AsyncGenreLoader(getActivity());
+    }
+
+    @Override
+    public void onLoadFinished(Loader<ArrayList<Genre>> loader, ArrayList<Genre> data) {
+        getAdapter().swapDataSet(data);
+    }
+
+    @Override
+    public void onLoaderReset(Loader<ArrayList<Genre>> loader) {
+        getAdapter().swapDataSet(new ArrayList<Genre>());
+    }
+
+    private static class AsyncGenreLoader extends WrappedAsyncTaskLoader<ArrayList<Genre>> {
+        public AsyncGenreLoader(Context context) {
+            super(context);
+        }
+
+        @Override
+        public ArrayList<Genre> loadInBackground() {
+            return GenreLoader.getAllGenres(getContext());
+        }
+    }
+}

app/src/main/java/com/kabouzeid/gramophone/util/NavigationUtil.java

@@ -12,9 +12,11 @@ import android.widget.Toast;
 
 import com.kabouzeid.gramophone.R;
 import com.kabouzeid.gramophone.helper.MusicPlayerRemote;
+import com.kabouzeid.gramophone.model.Genre;
 import com.kabouzeid.gramophone.model.Playlist;
 import com.kabouzeid.gramophone.ui.activities.AlbumDetailActivity;
 import com.kabouzeid.gramophone.ui.activities.ArtistDetailActivity;
+import com.kabouzeid.gramophone.ui.activities.GenreDetailActivity;
 import com.kabouzeid.gramophone.ui.activities.PlaylistDetailActivity;
 
 /**
@@ -38,6 +40,13 @@ public class NavigationUtil {
         activity.startActivity(intent, ActivityOptionsCompat.makeSceneTransitionAnimation(activity, sharedElements).toBundle());
     }
 
+    public static void goToGenre(@NonNull final Activity activity, final Genre genre, @Nullable Pair... sharedElements) {
+        final Intent intent = new Intent(activity, GenreDetailActivity.class);
+        intent.putExtra(GenreDetailActivity.EXTRA_GENRE, genre);
+
+        activity.startActivity(intent);
+    }
+
     public static void goToPlaylist(@NonNull final Activity activity, final Playlist playlist, @Nullable Pair... sharedElements) {
         final Intent intent = new Intent(activity, PlaylistDetailActivity.class);
         intent.putExtra(PlaylistDetailActivity.EXTRA_PLAYLIST, playlist);

app/src/main/java/com/kabouzeid/gramophone/util/PreferenceUtil.java

@@ -27,6 +27,7 @@ public final class PreferenceUtil {
     public static final String ALBUM_SORT_ORDER = "album_sort_order";
     public static final String ALBUM_SONG_SORT_ORDER = "album_song_sort_order";
     public static final String SONG_SORT_ORDER = "song_sort_order";
+    public static final String GENRE_SORT_ORDER = "genre_sort_order";
 
     public static final String ALBUM_GRID_SIZE = "album_grid_size";
     public static final String ALBUM_GRID_SIZE_LAND = "album_grid_size_land";
@@ -199,13 +200,11 @@ public final class PreferenceUtil {
     }
 
     public final String getArtistSongSortOrder() {
-        return mPreferences.getString(ARTIST_SONG_SORT_ORDER,
+        return mPreferences.getString(ARTIST_SONG_SORT_ORDER, SortOrder.ArtistSongSortOrder.SONG_A_Z);
-                SortOrder.ArtistSongSortOrder.SONG_A_Z);
     }
 
     public final String getArtistAlbumSortOrder() {
-        return mPreferences.getString(ARTIST_ALBUM_SORT_ORDER,
+        return mPreferences.getString(ARTIST_ALBUM_SORT_ORDER, SortOrder.ArtistAlbumSortOrder.ALBUM_YEAR);
-                SortOrder.ArtistAlbumSortOrder.ALBUM_YEAR);
     }
 
     public final String getAlbumSortOrder() {
@@ -213,14 +212,17 @@ public final class PreferenceUtil {
     }
 
     public final String getAlbumSongSortOrder() {
-        return mPreferences.getString(ALBUM_SONG_SORT_ORDER,
+        return mPreferences.getString(ALBUM_SONG_SORT_ORDER, SortOrder.AlbumSongSortOrder.SONG_TRACK_LIST);
-                SortOrder.AlbumSongSortOrder.SONG_TRACK_LIST);
     }
 
     public final String getSongSortOrder() {
         return mPreferences.getString(SONG_SORT_ORDER, SortOrder.SongSortOrder.SONG_A_Z);
     }
 
+    public final String getGenreSortOrder() {
+        return mPreferences.getString(GENRE_SORT_ORDER, SortOrder.GenreSortOrder.GENRE_A_Z);
+    }
+
     public long getLastAddedCutoff() {
         final CalendarUtil calendarUtil = new CalendarUtil();
         long interval;

app/src/main/res/layout/activity_genre_detail.xml

@@ -0,0 +1,55 @@
+<?xml version="1.0" encoding="utf-8"?>
+<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:transitionGroup="true"
+    tools:ignore="UnusedAttribute">
+
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:orientation="vertical">
+
+        <include layout="@layout/status_bar" />
+
+        <FrameLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:background="?colorPrimary"
+            android:elevation="@dimen/toolbar_elevation"
+            tools:ignore="UnusedAttribute">
+
+            <android.support.v7.widget.Toolbar
+                android:id="@+id/toolbar"
+                style="@style/Toolbar"
+                android:background="@android:color/transparent" />
+
+            <ViewStub
+                android:id="@+id/cab_stub"
+                android:layout_width="match_parent"
+                android:layout_height="?attr/actionBarSize" />
+
+        </FrameLayout>
+
+        <com.simplecityapps.recyclerview_fastscroll.views.FastScrollRecyclerView
+            android:id="@+id/recycler_view"
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"
+            android:clipToPadding="false"
+            android:scrollbars="none" />
+
+    </LinearLayout>
+
+    <TextView
+        android:id="@android:id/empty"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_gravity="center"
+        android:fontFamily="sans-serif-light"
+        android:text="@string/playlist_empty_text"
+        android:textColor="?android:textColorSecondary"
+        android:textSize="@dimen/empty_text_size"
+        android:visibility="gone" />
+
+</FrameLayout>

app/src/main/res/layout/item_list_simple.xml

@@ -0,0 +1,29 @@
+<?xml version="1.0" encoding="utf-8"?>
+<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="64dp"
+    android:foreground="?attr/rectSelector"
+    tools:ignore="UnusedAttribute">
+
+    <TextView
+        android:id="@+id/title"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:layout_centerVertical="true"
+        android:layout_marginEnd="16dp"
+        android:layout_marginLeft="16dp"
+        android:layout_marginRight="16dp"
+        android:layout_marginStart="16dp"
+        android:fontFamily="sans-serif"
+        android:singleLine="true"
+        android:textAppearance="@style/TextAppearance.AppCompat.Subhead" />
+
+    <View
+        android:id="@+id/separator"
+        android:layout_width="match_parent"
+        android:layout_height="1dp"
+        android:layout_gravity="bottom"
+        android:background="?attr/dividerColor" />
+
+</RelativeLayout>

app/src/main/res/menu/menu_genre_detail.xml

@@ -0,0 +1,12 @@
+<menu xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    tools:context="com.kabouzeid.gramophone.ui.activities.GenreDetailActivity">
+
+    <item
+        android:id="@+id/action_shuffle_genre"
+        android:icon="@drawable/ic_shuffle_white_24dp"
+        android:title="@string/action_shuffle_all"
+        app:showAsAction="ifRoom" />
+
+</menu>

app/src/main/res/values/strings.xml

@@ -30,6 +30,7 @@
     <string name="action_set_as_start_directory">Set as start directory</string>
     <string name="albums">Albums</string>
     <string name="artists">Artists</string>
+    <string name="genres">Genres</string>
     <string name="songs">Songs</string>
     <string name="playlists">Playlists</string>
     <string name="unplayable_file">Couldn\u2019t play this song.</string>
@@ -41,6 +42,7 @@
     <string name="album">Album</string>
     <string name="artist">Artist</string>
     <string name="genre">Genre</string>
+    <string name="unknown_genre">Unknown genre</string>
     <string name="album_artist">Album artist</string>
     <string name="year">Year</string>
     <string name="track_hint">"Track (2 for track 2 or 3004 for CD3 track 4)"</string>
@@ -150,6 +152,7 @@
     <string name="no_albums">No albums</string>
     <string name="no_songs">No songs</string>
     <string name="no_artists">No artists</string>
+    <string name="no_genres">No genres</string>
     <string name="empty">Empty</string>
     <string name="playlist_name_empty">Playlist name</string>
     <string name="song">Song</string>