Fix a big bunch of lint warning

app/src/main/java/com/cappielloantonio/play/broadcast/receiver/ConnectivityStatusBroadcastReceiver.java

@@ -9,7 +9,7 @@ import android.view.View;
 import com.cappielloantonio.play.ui.activity.MainActivity;
 
 public class ConnectivityStatusBroadcastReceiver extends BroadcastReceiver {
-    private MainActivity activity;
+    private final MainActivity activity;
 
     public ConnectivityStatusBroadcastReceiver(MainActivity activity) {
         this.activity = activity;

app/src/main/java/com/cappielloantonio/play/broadcast/receiver/MediaButtonIntentReceiver.java

@@ -47,7 +47,7 @@ public class MediaButtonIntentReceiver extends BroadcastReceiver {
     private static long mLastClickTime = 0;
 
     @SuppressLint("HandlerLeak")
-    private static Handler mHandler = new Handler() {
+    private static final Handler mHandler = new Handler() {
 
         @Override
         public void handleMessage(final Message msg) {

app/src/main/java/com/cappielloantonio/play/helper/MusicProgressViewUpdateHelper.java

@@ -14,9 +14,9 @@ public class MusicProgressViewUpdateHelper extends Handler {
     private static final int UPDATE_INTERVAL_PLAYING = 1000;
     private static final int UPDATE_INTERVAL_PAUSED = 500;
 
-    private Callback callback;
+    private final Callback callback;
-    private int intervalPlaying;
+    private final int intervalPlaying;
-    private int intervalPaused;
+    private final int intervalPaused;
 
     public MusicProgressViewUpdateHelper(Callback callback) {
         this.callback = callback;

app/src/main/java/com/cappielloantonio/play/helper/ThemeHelper.java

@@ -6,10 +6,11 @@ import androidx.annotation.NonNull;
 import androidx.appcompat.app.AppCompatDelegate;
 
 public class ThemeHelper {
+    private static final String TAG = "ThemeHelper";
+
     public static final String LIGHT_MODE = "light";
     public static final String DARK_MODE = "dark";
     public static final String DEFAULT_MODE = "default";
-    private static final String TAG = "ThemeHelper";
 
     public static void applyTheme(@NonNull String themePref) {
         switch (themePref) {

app/src/main/java/com/cappielloantonio/play/helper/recyclerview/GridItemDecoration.java

@@ -6,9 +6,9 @@ import android.view.View;
 import androidx.recyclerview.widget.RecyclerView;
 
 public class GridItemDecoration extends RecyclerView.ItemDecoration {
-    private int spanCount;
+    private final int spanCount;
-    private int spacing;
+    private final int spacing;
-    private boolean includeEdge;
+    private final boolean includeEdge;
 
     public GridItemDecoration(int spanCount, int spacing, boolean includeEdge) {
         this.spanCount = spanCount;

app/src/main/java/com/cappielloantonio/play/repository/AlbumRepository.java

@@ -27,7 +27,7 @@ import retrofit2.Response;
 public class AlbumRepository {
     private static final String TAG = "AlbumRepository";
 
-    private Application application;
+    private final Application application;
 
     public AlbumRepository(Application application) {
         this.application = application;

app/src/main/java/com/cappielloantonio/play/ui/fragment/AlbumCatalogueFragment.java

@@ -46,7 +46,7 @@ public class AlbumCatalogueFragment extends Fragment {
     }
 
     @Override
-    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
+    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
         activity = (MainActivity) getActivity();
 
         bind = FragmentAlbumCatalogueBinding.inflate(inflater, container, false);

app/src/main/java/com/cappielloantonio/play/ui/fragment/AlbumListPageFragment.java

@@ -5,6 +5,7 @@ import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 
+import androidx.annotation.NonNull;
 import androidx.core.view.ViewCompat;
 import androidx.fragment.app.Fragment;
 import androidx.lifecycle.ViewModelProvider;
@@ -25,7 +26,7 @@ public class AlbumListPageFragment extends Fragment {
     private AlbumHorizontalAdapter albumHorizontalAdapter;
 
     @Override
-    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
+    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
         activity = (MainActivity) getActivity();
 
         bind = FragmentAlbumListPageBinding.inflate(inflater, container, false);

app/src/main/java/com/cappielloantonio/play/ui/fragment/AlbumPageFragment.java

@@ -52,13 +52,13 @@ public class AlbumPageFragment extends Fragment {
     }
 
     @Override
-    public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
+    public void onCreateOptionsMenu(@NonNull Menu menu, @NonNull MenuInflater inflater) {
         super.onCreateOptionsMenu(menu, inflater);
         inflater.inflate(R.menu.album_page_menu, menu);
     }
 
     @Override
-    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
+    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
         activity = (MainActivity) getActivity();
 
         bind = FragmentAlbumPageBinding.inflate(inflater, container, false);
@@ -182,7 +182,7 @@ public class AlbumPageFragment extends Fragment {
         bind.songRecyclerView.setLayoutManager(new LinearLayoutManager(requireContext()));
         bind.songRecyclerView.setHasFixedSize(true);
 
-        songHorizontalAdapter = new SongHorizontalAdapter(activity, requireContext(), getChildFragmentManager());
+        songHorizontalAdapter = new SongHorizontalAdapter(activity, requireContext());
         bind.songRecyclerView.setAdapter(songHorizontalAdapter);
 
         albumPageViewModel.getAlbumSongLiveList().observe(requireActivity(), songs -> {

app/src/main/java/com/cappielloantonio/play/ui/fragment/ArtistCatalogueFragment.java

@@ -46,7 +46,7 @@ public class ArtistCatalogueFragment extends Fragment {
     }
 
     @Override
-    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
+    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
         activity = (MainActivity) getActivity();
 
         bind = FragmentArtistCatalogueBinding.inflate(inflater, container, false);

app/src/main/java/com/cappielloantonio/play/ui/fragment/ArtistListPageFragment.java

@@ -5,6 +5,7 @@ import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 
+import androidx.annotation.NonNull;
 import androidx.core.view.ViewCompat;
 import androidx.fragment.app.Fragment;
 import androidx.lifecycle.ViewModelProvider;
@@ -25,7 +26,7 @@ public class ArtistListPageFragment extends Fragment {
     private ArtistHorizontalAdapter artistHorizontalAdapter;
 
     @Override
-    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
+    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
         activity = (MainActivity) getActivity();
 
         bind = FragmentArtistListPageBinding.inflate(inflater, container, false);

app/src/main/java/com/cappielloantonio/play/ui/fragment/ArtistPageFragment.java

@@ -12,6 +12,7 @@ import android.view.View;
 import android.view.ViewGroup;
 import android.widget.Toast;
 
+import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.core.view.ViewCompat;
 import androidx.fragment.app.Fragment;
@@ -50,7 +51,7 @@ public class ArtistPageFragment extends Fragment {
     private ArtistSimilarAdapter artistSimilarAdapter;
 
     @Override
-    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
+    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
         activity = (MainActivity) getActivity();
 
         bind = FragmentArtistPageBinding.inflate(inflater, container, false);
@@ -175,7 +176,7 @@ public class ArtistPageFragment extends Fragment {
     private void initTopSongsView() {
         bind.mostStreamedSongRecyclerView.setLayoutManager(new LinearLayoutManager(requireContext()));
 
-        songHorizontalAdapter = new SongHorizontalAdapter(activity, requireContext(), getChildFragmentManager());
+        songHorizontalAdapter = new SongHorizontalAdapter(activity, requireContext());
         bind.mostStreamedSongRecyclerView.setAdapter(songHorizontalAdapter);
         artistPageViewModel.getArtistTopSongList(10).observe(requireActivity(), songs -> {
             if (bind != null) bind.artistPageTopSongsSector.setVisibility(!songs.isEmpty() ? View.VISIBLE : View.GONE);

app/src/main/java/com/cappielloantonio/play/ui/fragment/GenreCatalogueFragment.java

@@ -31,7 +31,6 @@ import com.cappielloantonio.play.viewmodel.GenreCatalogueViewModel;
 
 public class GenreCatalogueFragment extends Fragment {
     private static final String TAG = "GenreCatalogueFragment";
-    ;
 
     private FragmentGenreCatalogueBinding bind;
     private MainActivity activity;
@@ -46,7 +45,7 @@ public class GenreCatalogueFragment extends Fragment {
     }
 
     @Override
-    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
+    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
         activity = (MainActivity) getActivity();
 
         bind = FragmentGenreCatalogueBinding.inflate(inflater, container, false);

app/src/main/java/com/cappielloantonio/play/ui/fragment/HomeFragment.java

@@ -248,7 +248,7 @@ public class HomeFragment extends Fragment {
     private void initStarredTracksView() {
         bind.starredTracksRecyclerView.setHasFixedSize(true);
 
-        starredSongAdapter = new SongHorizontalAdapter(activity, requireContext(), getChildFragmentManager());
+        starredSongAdapter = new SongHorizontalAdapter(activity, requireContext());
         bind.starredTracksRecyclerView.setAdapter(starredSongAdapter);
         homeViewModel.getStarredTracks().observe(requireActivity(), songs -> {
             if (bind != null) {

app/src/main/java/com/cappielloantonio/play/ui/fragment/LoginFragment.java

@@ -43,7 +43,7 @@ public class LoginFragment extends Fragment {
     }
 
     @Override
-    public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
+    public void onCreateOptionsMenu(@NonNull Menu menu, @NonNull MenuInflater inflater) {
         super.onCreateOptionsMenu(menu, inflater);
         inflater.inflate(R.menu.login_page_menu, menu);
     }

app/src/main/java/com/cappielloantonio/play/ui/fragment/PlayerBottomSheetFragment.java

@@ -113,9 +113,7 @@ public class PlayerBottomSheetFragment extends Fragment implements MusicServiceE
 
         playerNowPlayingSongAdapter = new PlayerNowPlayingSongAdapter(requireContext());
         bind.playerBodyLayout.playerSongCoverViewPager.setAdapter(playerNowPlayingSongAdapter);
-        playerBottomSheetViewModel.getQueueSong().observe(requireActivity(), queue -> {
+        playerBottomSheetViewModel.getQueueSong().observe(requireActivity(), queue -> playerNowPlayingSongAdapter.setItems(MappingUtil.mapQueue(queue)));
-            playerNowPlayingSongAdapter.setItems(MappingUtil.mapQueue(queue));
-        });
 
         bind.playerBodyLayout.playerSongCoverViewPager.setOffscreenPageLimit(3);
         bind.playerBodyLayout.playerSongCoverViewPager.registerOnPageChangeCallback(new ViewPager2.OnPageChangeCallback() {
@@ -151,9 +149,7 @@ public class PlayerBottomSheetFragment extends Fragment implements MusicServiceE
 
         playerSongQueueAdapter = new PlayerSongQueueAdapter(requireContext(), this);
         bind.playerBodyLayout.playerQueueRecyclerView.setAdapter(playerSongQueueAdapter);
-        playerBottomSheetViewModel.getQueueSong().observe(requireActivity(), queue -> {
+        playerBottomSheetViewModel.getQueueSong().observe(requireActivity(), queue -> playerSongQueueAdapter.setItems(MappingUtil.mapQueue(queue)));
-            playerSongQueueAdapter.setItems(MappingUtil.mapQueue(queue));
-        });
 
         new ItemTouchHelper(new ItemTouchHelper.SimpleCallback(ItemTouchHelper.UP | ItemTouchHelper.DOWN, ItemTouchHelper.LEFT) {
             int originalPosition = -1;
@@ -161,7 +157,7 @@ public class PlayerBottomSheetFragment extends Fragment implements MusicServiceE
             int toPosition = -1;
 
             @Override
-            public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
+            public boolean onMove(@NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
                 if (originalPosition == -1)
                     originalPosition = viewHolder.getBindingAdapterPosition();
 
@@ -203,7 +199,7 @@ public class PlayerBottomSheetFragment extends Fragment implements MusicServiceE
             }
 
             @Override
-            public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {
+            public void onSwiped(@NonNull RecyclerView.ViewHolder viewHolder, int direction) {
                 if (!(viewHolder.getBindingAdapterPosition() == MusicPlayerRemote.getPosition()) && !(MusicPlayerRemote.getPlayingQueue().size() <= 1)) {
                     MusicPlayerRemote.removeFromQueue(viewHolder.getBindingAdapterPosition());
                     playerBottomSheetViewModel.removeSong(viewHolder.getBindingAdapterPosition());
@@ -295,11 +291,7 @@ public class PlayerBottomSheetFragment extends Fragment implements MusicServiceE
     }
 
     protected void updatePlayPauseState() {
-        if (MusicPlayerRemote.isPlaying()) {
+        bind.playerHeaderLayout.playerHeaderButton.setChecked(!MusicPlayerRemote.isPlaying());
-            bind.playerHeaderLayout.playerHeaderButton.setChecked(false);
-        } else {
-            bind.playerHeaderLayout.playerHeaderButton.setChecked(true);
-        }
     }
 
     private void setUpMusicControllers() {

app/src/main/java/com/cappielloantonio/play/ui/fragment/PlaylistCatalogueFragment.java

@@ -28,7 +28,6 @@ import com.cappielloantonio.play.viewmodel.PlaylistCatalogueViewModel;
 
 public class PlaylistCatalogueFragment extends Fragment {
     private static final String TAG = "GenreCatalogueFragment";
-    ;
 
     private FragmentPlaylistCatalogueBinding bind;
     private MainActivity activity;
@@ -45,7 +44,7 @@ public class PlaylistCatalogueFragment extends Fragment {
     }
 
     @Override
-    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
+    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
         activity = (MainActivity) getActivity();
 
         bind = FragmentPlaylistCatalogueBinding.inflate(inflater, container, false);

app/src/main/java/com/cappielloantonio/play/ui/fragment/PlaylistPageFragment.java

@@ -46,13 +46,13 @@ public class PlaylistPageFragment extends Fragment {
     }
 
     @Override
-    public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
+    public void onCreateOptionsMenu(@NonNull Menu menu, @NonNull MenuInflater inflater) {
         super.onCreateOptionsMenu(menu, inflater);
         inflater.inflate(R.menu.playlist_page_menu, menu);
     }
 
     @Override
-    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
+    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
         activity = (MainActivity) getActivity();
 
         bind = FragmentPlaylistPageBinding.inflate(inflater, container, false);
@@ -154,7 +154,7 @@ public class PlaylistPageFragment extends Fragment {
         bind.songRecyclerView.setLayoutManager(new LinearLayoutManager(requireContext()));
         bind.songRecyclerView.setHasFixedSize(true);
 
-        songHorizontalAdapter = new SongHorizontalAdapter(activity, requireContext(), getChildFragmentManager());
+        songHorizontalAdapter = new SongHorizontalAdapter(activity, requireContext());
         bind.songRecyclerView.setAdapter(songHorizontalAdapter);
 
         playlistPageViewModel.getPlaylistSongLiveList().observe(requireActivity(), songs -> {

app/src/main/java/com/cappielloantonio/play/ui/fragment/SearchFragment.java

@@ -73,7 +73,7 @@ public class SearchFragment extends Fragment {
         bind.searchResultTracksRecyclerView.setLayoutManager(new LinearLayoutManager(requireContext()));
         bind.searchResultTracksRecyclerView.setHasFixedSize(true);
 
-        songHorizontalAdapter = new SongHorizontalAdapter(activity, requireContext(), getChildFragmentManager());
+        songHorizontalAdapter = new SongHorizontalAdapter(activity, requireContext());
         bind.searchResultTracksRecyclerView.setAdapter(songHorizontalAdapter);
 
         // Albums
@@ -107,9 +107,7 @@ public class SearchFragment extends Fragment {
 
         bind.persistentSearchView.setOnSearchQueryChangeListener((searchView, oldQuery, newQuery) -> {
             if (!newQuery.trim().equals("") && newQuery.trim().length() > 1) {
-                searchViewModel.getSearchSuggestion(newQuery).observe(requireActivity(), suggestions -> {
+                searchViewModel.getSearchSuggestion(newQuery).observe(requireActivity(), suggestions -> searchView.setSuggestions(SuggestionCreationUtil.asRegularSearchSuggestions(MusicUtil.getReadableStrings(suggestions)), false));
-                    searchView.setSuggestions(SuggestionCreationUtil.asRegularSearchSuggestions(MusicUtil.getReadableStrings(suggestions)), false);
-                });
             } else {
                 setSuggestions();
             }

app/src/main/java/com/cappielloantonio/play/ui/fragment/SettingsFragment.java

@@ -5,6 +5,7 @@ import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 
+import androidx.annotation.NonNull;
 import androidx.lifecycle.ViewModelProvider;
 import androidx.preference.ListPreference;
 import androidx.preference.PreferenceFragmentCompat;
@@ -23,7 +24,7 @@ public class SettingsFragment extends PreferenceFragmentCompat {
     private SettingViewModel settingViewModel;
 
     @Override
-    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
+    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
         activity = (MainActivity) getActivity();
 
         View view = super.onCreateView(inflater, container, savedInstanceState);

app/src/main/java/com/cappielloantonio/play/ui/fragment/SongListPageFragment.java

@@ -6,6 +6,7 @@ import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 
+import androidx.annotation.NonNull;
 import androidx.core.view.ViewCompat;
 import androidx.fragment.app.Fragment;
 import androidx.lifecycle.ViewModelProvider;
@@ -32,7 +33,7 @@ public class SongListPageFragment extends Fragment {
     private SongHorizontalAdapter songHorizontalAdapter;
 
     @Override
-    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
+    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
         activity = (MainActivity) getActivity();
 
         bind = FragmentSongListPageBinding.inflate(inflater, container, false);
@@ -103,9 +104,7 @@ public class SongListPageFragment extends Fragment {
             activity.getSupportActionBar().setDisplayShowHomeEnabled(true);
         }
 
-        bind.toolbar.setNavigationOnClickListener(v -> {
+        bind.toolbar.setNavigationOnClickListener(v -> activity.navController.navigateUp());
-            activity.navController.navigateUp();
-        });
 
         bind.appBarLayout.addOnOffsetChangedListener((appBarLayout, verticalOffset) -> {
             if ((bind.albumInfoSector.getHeight() + verticalOffset) < (2 * ViewCompat.getMinimumHeight(bind.toolbar))) {
@@ -138,7 +137,7 @@ public class SongListPageFragment extends Fragment {
         bind.songListRecyclerView.setLayoutManager(new LinearLayoutManager(requireContext()));
         bind.songListRecyclerView.setHasFixedSize(true);
 
-        songHorizontalAdapter = new SongHorizontalAdapter(activity, requireContext(), getChildFragmentManager());
+        songHorizontalAdapter = new SongHorizontalAdapter(activity, requireContext());
         bind.songListRecyclerView.setAdapter(songHorizontalAdapter);
         songListPageViewModel.getSongList().observe(requireActivity(), songs -> songHorizontalAdapter.setItems(songs));
     }

app/src/main/java/com/cappielloantonio/play/ui/fragment/bottomsheetdialog/AlbumBottomSheetDialog.java

@@ -39,8 +39,6 @@ import java.util.List;
 public class AlbumBottomSheetDialog extends BottomSheetDialogFragment implements View.OnClickListener {
     private static final String TAG = "AlbumBottomSheetDialog";
 
-    private MainActivity activity;
-
     private AlbumBottomSheetViewModel albumBottomSheetViewModel;
     private Album album;
 
@@ -60,8 +58,6 @@ public class AlbumBottomSheetDialog extends BottomSheetDialogFragment implements
     }
 
     private void init(View view) {
-        activity = (MainActivity) requireActivity();
-
         ImageView coverAlbum = view.findViewById(R.id.album_cover_image_view);
         CustomGlideRequest.Builder
                 .from(requireContext(), albumBottomSheetViewModel.getAlbum().getPrimary(), CustomGlideRequest.ALBUM_PIC, null)
@@ -100,8 +96,8 @@ public class AlbumBottomSheetDialog extends BottomSheetDialogFragment implements
                         QueueRepository queueRepository = new QueueRepository(App.getInstance());
                         queueRepository.insertAllAndStartNew((ArrayList<Song>) media);
 
-                        activity.isBottomSheetInPeek(true);
+                        ((MainActivity) requireActivity()).isBottomSheetInPeek(true);
-                        activity.setBottomSheetMusicInfo((Song) media.get(0));
+                        ((MainActivity) requireActivity()).setBottomSheetMusicInfo((Song) media.get(0));
 
                         MusicPlayerRemote.openQueue((List<Song>) media, 0, true);
                     } else {
@@ -123,7 +119,7 @@ public class AlbumBottomSheetDialog extends BottomSheetDialogFragment implements
                 queueRepository.insertAllAndStartNew(songs);
 
                 MusicPlayerRemote.openQueue(songs, 0, true);
-                activity.isBottomSheetInPeek(true);
+                ((MainActivity) requireActivity()).isBottomSheetInPeek(true);
 
                 dismissBottomSheet();
             });
@@ -133,7 +129,7 @@ public class AlbumBottomSheetDialog extends BottomSheetDialogFragment implements
         playNext.setOnClickListener(v -> {
             albumBottomSheetViewModel.getAlbumTracks().observe(requireActivity(), songs -> {
                 MusicPlayerRemote.playNext(songs);
-                activity.isBottomSheetInPeek(true);
+                ((MainActivity) requireActivity()).isBottomSheetInPeek(true);
                 dismissBottomSheet();
             });
         });

app/src/main/java/com/cappielloantonio/play/ui/fragment/bottomsheetdialog/ArtistBottomSheetDialog.java

@@ -36,8 +36,6 @@ import java.util.List;
 public class ArtistBottomSheetDialog extends BottomSheetDialogFragment implements View.OnClickListener {
     private static final String TAG = "AlbumBottomSheetDialog";
 
-    private MainActivity activity;
-
     private ArtistBottomSheetViewModel artistBottomSheetViewModel;
     private Artist artist;
 
@@ -57,8 +55,6 @@ public class ArtistBottomSheetDialog extends BottomSheetDialogFragment implement
     }
 
     private void init(View view) {
-        activity = (MainActivity) requireActivity();
-
         ImageView coverArtist = view.findViewById(R.id.artist_cover_image_view);
         CustomGlideRequest.Builder
                 .from(requireContext(), artistBottomSheetViewModel.getArtist().getPrimary(), CustomGlideRequest.ARTIST_PIC, null)
@@ -94,8 +90,8 @@ public class ArtistBottomSheetDialog extends BottomSheetDialogFragment implement
                         QueueRepository queueRepository = new QueueRepository(App.getInstance());
                         queueRepository.insertAllAndStartNew((ArrayList<Song>) media);
 
-                        activity.isBottomSheetInPeek(true);
+                        ((MainActivity) requireActivity()).isBottomSheetInPeek(true);
-                        activity.setBottomSheetMusicInfo((Song) media.get(0));
+                        ((MainActivity) requireActivity()).setBottomSheetMusicInfo((Song) media.get(0));
 
                         MusicPlayerRemote.openQueue((List<Song>) media, 0, true);
                     } else {
@@ -116,7 +112,7 @@ public class ArtistBottomSheetDialog extends BottomSheetDialogFragment implement
                     queueRepository.insertAllAndStartNew(songs);
 
                     MusicPlayerRemote.openQueue(songs, 0, true);
-                    activity.isBottomSheetInPeek(true);
+                    ((MainActivity) requireActivity()).isBottomSheetInPeek(true);
                 } else {
                     Toast.makeText(requireContext(), "Error retrieving artist's songs", Toast.LENGTH_SHORT).show();
                 }

app/src/main/java/com/cappielloantonio/play/ui/fragment/bottomsheetdialog/SongBottomSheetDialog.java

@@ -43,8 +43,6 @@ public class SongBottomSheetDialog extends BottomSheetDialogFragment implements
     private SongBottomSheetViewModel songBottomSheetViewModel;
     private Song song;
 
-    private TextView download;
-
     @Nullable
     @Override
     public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
@@ -149,7 +147,7 @@ public class SongBottomSheetDialog extends BottomSheetDialogFragment implements
             dismissBottomSheet();
         });
 
-        download = view.findViewById(R.id.download_text_view);
+        TextView download = view.findViewById(R.id.download_text_view);
         download.setOnClickListener(v -> {
             DownloadUtil.getDownloadTracker(requireContext()).toggleDownload(Arrays.asList(song));
             dismissBottomSheet();

app/src/main/java/com/cappielloantonio/play/ui/fragment/dialog/PlaylistChooserDialog.java

@@ -6,6 +6,7 @@ import android.os.Bundle;
 import android.view.LayoutInflater;
 import android.view.View;
 
+import androidx.annotation.NonNull;
 import androidx.fragment.app.DialogFragment;
 import androidx.lifecycle.ViewModelProvider;
 import androidx.recyclerview.widget.LinearLayoutManager;
@@ -25,6 +26,7 @@ public class PlaylistChooserDialog extends DialogFragment {
 
     private PlaylistHorizontalAdapter playlistHorizontalAdapter;
 
+    @NonNull
     @Override
     public Dialog onCreateDialog(Bundle savedInstanceState) {
         bind = DialogPlaylistChooserBinding.inflate(LayoutInflater.from(requireContext()));

app/src/main/java/com/cappielloantonio/play/ui/fragment/dialog/PlaylistEditorDialog.java

@@ -28,16 +28,14 @@ public class PlaylistEditorDialog extends DialogFragment {
     private static final String TAG = "ServerSignupDialog";
 
     private DialogPlaylistEditorBinding bind;
-    private MainActivity activity;
     private PlaylistEditorViewModel playlistEditorViewModel;
 
     private String playlistName;
     private PlaylistDialogSongHorizontalAdapter playlistDialogSongHorizontalAdapter;
 
+    @NonNull
     @Override
     public Dialog onCreateDialog(Bundle savedInstanceState) {
-        activity = (MainActivity) getActivity();
-
         bind = DialogPlaylistEditorBinding.inflate(LayoutInflater.from(requireContext()));
         playlistEditorViewModel = new ViewModelProvider(requireActivity()).get(PlaylistEditorViewModel.class);
 

app/src/main/java/com/cappielloantonio/play/ui/fragment/dialog/RatingDialog.java

@@ -6,6 +6,7 @@ import android.content.Context;
 import android.os.Bundle;
 import android.view.LayoutInflater;
 
+import androidx.annotation.NonNull;
 import androidx.fragment.app.DialogFragment;
 import androidx.lifecycle.ViewModelProvider;
 
@@ -22,6 +23,7 @@ public class RatingDialog extends DialogFragment {
     private DialogRatingBinding bind;
     private RatingViewModel ratingViewModel;
 
+    @NonNull
     @Override
     public Dialog onCreateDialog(Bundle savedInstanceState) {
         bind = DialogRatingBinding.inflate(LayoutInflater.from(requireContext()));

app/src/main/java/com/cappielloantonio/play/ui/fragment/dialog/ServerSignupDialog.java

@@ -9,6 +9,7 @@ import android.util.Log;
 import android.view.LayoutInflater;
 import android.widget.Toast;
 
+import androidx.annotation.NonNull;
 import androidx.fragment.app.DialogFragment;
 import androidx.lifecycle.ViewModelProvider;
 
@@ -41,6 +42,7 @@ public class ServerSignupDialog extends DialogFragment {
     private String server;
     private boolean directAccess = false;
 
+    @NonNull
     @Override
     public Dialog onCreateDialog(Bundle savedInstanceState) {
         activity = (MainActivity) getActivity();

app/src/main/java/com/cappielloantonio/play/util/MusicUtil.java

@@ -89,16 +89,17 @@ public class MusicUtil {
     }
 
     public static int getDefaultPicPerCategory(String category) {
-        if (category.equals(CustomGlideRequest.SONG_PIC)) {
+        switch (category) {
-            return R.drawable.default_album_art;
+            case CustomGlideRequest.SONG_PIC:
-        } else if (category.equals(CustomGlideRequest.ALBUM_PIC)) {
+                return R.drawable.default_album_art;
-            return R.drawable.default_album_art;
+            case CustomGlideRequest.ALBUM_PIC:
-        } else if (category.equals(CustomGlideRequest.ARTIST_PIC)) {
+                return R.drawable.default_album_art;
-            return R.drawable.default_album_art;
+            case CustomGlideRequest.ARTIST_PIC:
-        } else if (category.equals(CustomGlideRequest.PLAYLIST_PIC)) {
+                return R.drawable.default_album_art;
-            return R.drawable.default_album_art;
+            case CustomGlideRequest.PLAYLIST_PIC:
-        } else {
+                return R.drawable.default_album_art;
-            return R.drawable.default_album_art;
+            default:
+                return R.drawable.default_album_art;
         }
     }