diff --git a/app/src/main/java/com/cappielloantonio/play/adapter/AlbumAdapter.java b/app/src/main/java/com/cappielloantonio/play/adapter/AlbumAdapter.java
index 090a97f3..f151a95b 100644
--- a/app/src/main/java/com/cappielloantonio/play/adapter/AlbumAdapter.java
+++ b/app/src/main/java/com/cappielloantonio/play/adapter/AlbumAdapter.java
@@ -2,9 +2,7 @@ package com.cappielloantonio.play.adapter;
 
 import android.content.Context;
 import android.os.Bundle;
-import android.text.Html;
 import android.view.LayoutInflater;
-import android.view.RoundedCorner;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.ImageView;
diff --git a/app/src/main/java/com/cappielloantonio/play/adapter/AlbumArtistPageOrSimilarAdapter.java b/app/src/main/java/com/cappielloantonio/play/adapter/AlbumArtistPageOrSimilarAdapter.java
index 19510030..525041be 100644
--- a/app/src/main/java/com/cappielloantonio/play/adapter/AlbumArtistPageOrSimilarAdapter.java
+++ b/app/src/main/java/com/cappielloantonio/play/adapter/AlbumArtistPageOrSimilarAdapter.java
@@ -2,7 +2,6 @@ package com.cappielloantonio.play.adapter;
 
 import android.content.Context;
 import android.os.Bundle;
-import android.text.Html;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
diff --git a/app/src/main/java/com/cappielloantonio/play/adapter/AlbumCatalogueAdapter.java b/app/src/main/java/com/cappielloantonio/play/adapter/AlbumCatalogueAdapter.java
index 0f4720b4..350a47cf 100644
--- a/app/src/main/java/com/cappielloantonio/play/adapter/AlbumCatalogueAdapter.java
+++ b/app/src/main/java/com/cappielloantonio/play/adapter/AlbumCatalogueAdapter.java
@@ -2,7 +2,6 @@ package com.cappielloantonio.play.adapter;
 
 import android.content.Context;
 import android.os.Bundle;
-import android.text.Html;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
diff --git a/app/src/main/java/com/cappielloantonio/play/adapter/ArtistAdapter.java b/app/src/main/java/com/cappielloantonio/play/adapter/ArtistAdapter.java
index 3e2a2ef0..dc40c6ff 100644
--- a/app/src/main/java/com/cappielloantonio/play/adapter/ArtistAdapter.java
+++ b/app/src/main/java/com/cappielloantonio/play/adapter/ArtistAdapter.java
@@ -2,7 +2,6 @@ package com.cappielloantonio.play.adapter;
 
 import android.content.Context;
 import android.os.Bundle;
-import android.text.Html;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
diff --git a/app/src/main/java/com/cappielloantonio/play/adapter/ArtistCatalogueAdapter.java b/app/src/main/java/com/cappielloantonio/play/adapter/ArtistCatalogueAdapter.java
index 1026cbd0..4fc166cf 100644
--- a/app/src/main/java/com/cappielloantonio/play/adapter/ArtistCatalogueAdapter.java
+++ b/app/src/main/java/com/cappielloantonio/play/adapter/ArtistCatalogueAdapter.java
@@ -2,7 +2,6 @@ package com.cappielloantonio.play.adapter;
 
 import android.content.Context;
 import android.os.Bundle;
-import android.text.Html;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
diff --git a/app/src/main/java/com/cappielloantonio/play/adapter/ArtistHorizontalAdapter.java b/app/src/main/java/com/cappielloantonio/play/adapter/ArtistHorizontalAdapter.java
index f1bd185d..f6bac81c 100644
--- a/app/src/main/java/com/cappielloantonio/play/adapter/ArtistHorizontalAdapter.java
+++ b/app/src/main/java/com/cappielloantonio/play/adapter/ArtistHorizontalAdapter.java
@@ -95,10 +95,7 @@ public class ArtistHorizontalAdapter extends RecyclerView.Adapter<ArtistHorizont
             itemView.setOnClickListener(this);
             itemView.setOnLongClickListener(this);
 
-            more.setOnClickListener(v -> {
-                openMore(v);
-            });
-
+            more.setOnClickListener(this::openMore);
             artistName.setSelected(true);
         }
 
diff --git a/app/src/main/java/com/cappielloantonio/play/adapter/ArtistSimilarAdapter.java b/app/src/main/java/com/cappielloantonio/play/adapter/ArtistSimilarAdapter.java
index e1b02588..24a941d6 100644
--- a/app/src/main/java/com/cappielloantonio/play/adapter/ArtistSimilarAdapter.java
+++ b/app/src/main/java/com/cappielloantonio/play/adapter/ArtistSimilarAdapter.java
@@ -2,7 +2,6 @@ package com.cappielloantonio.play.adapter;
 
 import android.content.Context;
 import android.os.Bundle;
-import android.text.Html;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
diff --git a/app/src/main/java/com/cappielloantonio/play/adapter/DiscoverSongAdapter.java b/app/src/main/java/com/cappielloantonio/play/adapter/DiscoverSongAdapter.java
index 4a31c67a..0455c662 100644
--- a/app/src/main/java/com/cappielloantonio/play/adapter/DiscoverSongAdapter.java
+++ b/app/src/main/java/com/cappielloantonio/play/adapter/DiscoverSongAdapter.java
@@ -1,7 +1,6 @@
 package com.cappielloantonio.play.adapter;
 
 import android.content.Context;
-import android.text.Html;
 import android.util.Log;
 import android.view.LayoutInflater;
 import android.view.View;
@@ -13,7 +12,6 @@ import android.widget.TextView;
 import androidx.annotation.NonNull;
 import androidx.recyclerview.widget.RecyclerView;
 
-import com.bumptech.glide.load.resource.bitmap.RoundedCorners;
 import com.cappielloantonio.play.App;
 import com.cappielloantonio.play.R;
 import com.cappielloantonio.play.glide.CustomGlideRequest;
diff --git a/app/src/main/java/com/cappielloantonio/play/adapter/GenreAdapter.java b/app/src/main/java/com/cappielloantonio/play/adapter/GenreAdapter.java
index 912c2c54..ab49ed66 100644
--- a/app/src/main/java/com/cappielloantonio/play/adapter/GenreAdapter.java
+++ b/app/src/main/java/com/cappielloantonio/play/adapter/GenreAdapter.java
@@ -1,7 +1,6 @@
 package com.cappielloantonio.play.adapter;
 
 import android.content.Context;
-import android.text.Html;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
diff --git a/app/src/main/java/com/cappielloantonio/play/adapter/GenreCatalogueAdapter.java b/app/src/main/java/com/cappielloantonio/play/adapter/GenreCatalogueAdapter.java
index a6500c5a..d4fab17b 100644
--- a/app/src/main/java/com/cappielloantonio/play/adapter/GenreCatalogueAdapter.java
+++ b/app/src/main/java/com/cappielloantonio/play/adapter/GenreCatalogueAdapter.java
@@ -1,7 +1,6 @@
 package com.cappielloantonio.play.adapter;
 
 import android.content.Context;
-import android.text.Html;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
diff --git a/app/src/main/java/com/cappielloantonio/play/adapter/PlayerSongQueueAdapter.java b/app/src/main/java/com/cappielloantonio/play/adapter/PlayerSongQueueAdapter.java
index 0a4e8ed4..cc26ab4d 100644
--- a/app/src/main/java/com/cappielloantonio/play/adapter/PlayerSongQueueAdapter.java
+++ b/app/src/main/java/com/cappielloantonio/play/adapter/PlayerSongQueueAdapter.java
@@ -1,7 +1,6 @@
 package com.cappielloantonio.play.adapter;
 
 import android.content.Context;
-import android.text.Html;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
diff --git a/app/src/main/java/com/cappielloantonio/play/adapter/PlaylistCatalogueAdapter.java b/app/src/main/java/com/cappielloantonio/play/adapter/PlaylistCatalogueAdapter.java
index 5ec003ec..b6f16f65 100644
--- a/app/src/main/java/com/cappielloantonio/play/adapter/PlaylistCatalogueAdapter.java
+++ b/app/src/main/java/com/cappielloantonio/play/adapter/PlaylistCatalogueAdapter.java
@@ -2,7 +2,6 @@ package com.cappielloantonio.play.adapter;
 
 import android.content.Context;
 import android.os.Bundle;
-import android.text.Html;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
@@ -16,13 +15,10 @@ import androidx.annotation.NonNull;
 import androidx.navigation.Navigation;
 import androidx.recyclerview.widget.RecyclerView;
 
-import com.bumptech.glide.load.resource.bitmap.RoundedCorners;
 import com.cappielloantonio.play.R;
 import com.cappielloantonio.play.glide.CustomGlideRequest;
 import com.cappielloantonio.play.model.Playlist;
-import com.cappielloantonio.play.model.Song;
 import com.cappielloantonio.play.ui.activity.MainActivity;
-import com.cappielloantonio.play.ui.fragment.dialog.PlaylistChooserDialog;
 import com.cappielloantonio.play.ui.fragment.dialog.PlaylistEditorDialog;
 import com.cappielloantonio.play.util.MusicUtil;
 
diff --git a/app/src/main/java/com/cappielloantonio/play/adapter/PlaylistDialogSongHorizontalAdapter.java b/app/src/main/java/com/cappielloantonio/play/adapter/PlaylistDialogSongHorizontalAdapter.java
index 7d367a43..90353bb5 100644
--- a/app/src/main/java/com/cappielloantonio/play/adapter/PlaylistDialogSongHorizontalAdapter.java
+++ b/app/src/main/java/com/cappielloantonio/play/adapter/PlaylistDialogSongHorizontalAdapter.java
@@ -1,7 +1,6 @@
 package com.cappielloantonio.play.adapter;
 
 import android.content.Context;
-import android.os.Bundle;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
@@ -9,20 +8,12 @@ import android.widget.ImageView;
 import android.widget.TextView;
 
 import androidx.annotation.NonNull;
-import androidx.fragment.app.FragmentManager;
-import androidx.navigation.Navigation;
 import androidx.recyclerview.widget.RecyclerView;
 
 import com.bumptech.glide.load.resource.bitmap.RoundedCorners;
-import com.cappielloantonio.play.App;
 import com.cappielloantonio.play.R;
 import com.cappielloantonio.play.glide.CustomGlideRequest;
-import com.cappielloantonio.play.model.Playlist;
 import com.cappielloantonio.play.model.Song;
-import com.cappielloantonio.play.repository.QueueRepository;
-import com.cappielloantonio.play.service.MusicPlayerRemote;
-import com.cappielloantonio.play.ui.activity.MainActivity;
-import com.cappielloantonio.play.util.DownloadUtil;
 import com.cappielloantonio.play.util.MusicUtil;
 
 import java.util.ArrayList;
@@ -32,8 +23,8 @@ public class PlaylistDialogSongHorizontalAdapter extends RecyclerView.Adapter<Pl
     private static final String TAG = "PlaylistDialogSongHorizontalAdapter";
 
     private List<Song> songs;
-    private LayoutInflater mInflater;
-    private Context context;
+    private final LayoutInflater mInflater;
+    private final Context context;
 
     public PlaylistDialogSongHorizontalAdapter(Context context) {
         this.context = context;
@@ -81,7 +72,7 @@ public class PlaylistDialogSongHorizontalAdapter extends RecyclerView.Adapter<Pl
         return songs.get(id);
     }
 
-    public class ViewHolder extends RecyclerView.ViewHolder {
+    public static class ViewHolder extends RecyclerView.ViewHolder {
         TextView songTitle;
         TextView songArtist;
         TextView songDuration;
diff --git a/app/src/main/java/com/cappielloantonio/play/adapter/ServerAdapter.java b/app/src/main/java/com/cappielloantonio/play/adapter/ServerAdapter.java
index ddb66e4e..76e62231 100644
--- a/app/src/main/java/com/cappielloantonio/play/adapter/ServerAdapter.java
+++ b/app/src/main/java/com/cappielloantonio/play/adapter/ServerAdapter.java
@@ -9,15 +9,12 @@ import android.widget.TextView;
 import android.widget.Toast;
 
 import androidx.annotation.NonNull;
-import androidx.fragment.app.FragmentManager;
-import androidx.navigation.Navigation;
 import androidx.recyclerview.widget.RecyclerView;
 
 import com.cappielloantonio.play.App;
 import com.cappielloantonio.play.R;
 import com.cappielloantonio.play.interfaces.SystemCallback;
 import com.cappielloantonio.play.model.Server;
-import com.cappielloantonio.play.model.Song;
 import com.cappielloantonio.play.repository.SystemRepository;
 import com.cappielloantonio.play.ui.activity.MainActivity;
 import com.cappielloantonio.play.ui.fragment.dialog.ServerSignupDialog;
@@ -25,7 +22,6 @@ import com.cappielloantonio.play.util.PreferenceUtil;
 
 import java.util.ArrayList;
 import java.util.List;
-import java.util.UUID;
 
 public class ServerAdapter extends RecyclerView.Adapter<ServerAdapter.ViewHolder> {
     private static final String TAG = "ServerAdapter";
diff --git a/app/src/main/java/com/cappielloantonio/play/adapter/SongHorizontalAdapter.java b/app/src/main/java/com/cappielloantonio/play/adapter/SongHorizontalAdapter.java
index b8b0f6fc..f26e38db 100644
--- a/app/src/main/java/com/cappielloantonio/play/adapter/SongHorizontalAdapter.java
+++ b/app/src/main/java/com/cappielloantonio/play/adapter/SongHorizontalAdapter.java
@@ -2,7 +2,6 @@ package com.cappielloantonio.play.adapter;
 
 import android.content.Context;
 import android.os.Bundle;
-import android.text.Html;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
@@ -10,7 +9,6 @@ import android.widget.ImageView;
 import android.widget.TextView;
 
 import androidx.annotation.NonNull;
-import androidx.fragment.app.FragmentManager;
 import androidx.navigation.Navigation;
 import androidx.recyclerview.widget.RecyclerView;
 
@@ -68,15 +66,15 @@ public class SongHorizontalAdapter extends RecyclerView.Adapter<SongHorizontalAd
             holder.downloadIndicator.setVisibility(View.GONE);
         }
 
-        if(isCoverVisible) CustomGlideRequest.Builder
+        if (isCoverVisible) CustomGlideRequest.Builder
                 .from(context, song.getPrimary(), CustomGlideRequest.SONG_PIC, null)
                 .build()
                 .transform(new RoundedCorners(CustomGlideRequest.CORNER_RADIUS))
                 .into(holder.cover);
 
-        if(isCoverVisible) holder.trackNumber.setVisibility(View.INVISIBLE);
+        if (isCoverVisible) holder.trackNumber.setVisibility(View.INVISIBLE);
 
-        if(!isCoverVisible) holder.cover.setVisibility(View.INVISIBLE);
+        if (!isCoverVisible) holder.cover.setVisibility(View.INVISIBLE);
     }
 
     @Override
diff --git a/app/src/main/java/com/cappielloantonio/play/broadcast/receiver/MediaButtonIntentReceiver.java b/app/src/main/java/com/cappielloantonio/play/broadcast/receiver/MediaButtonIntentReceiver.java
index cece60d5..28b6b7e7 100644
--- a/app/src/main/java/com/cappielloantonio/play/broadcast/receiver/MediaButtonIntentReceiver.java
+++ b/app/src/main/java/com/cappielloantonio/play/broadcast/receiver/MediaButtonIntentReceiver.java
@@ -48,7 +48,6 @@ public class MediaButtonIntentReceiver extends BroadcastReceiver {
 
     @SuppressLint("HandlerLeak")
     private static final Handler mHandler = new Handler() {
-
         @Override
         public void handleMessage(final Message msg) {
             switch (msg.what) {
diff --git a/app/src/main/java/com/cappielloantonio/play/database/AppDatabase.java b/app/src/main/java/com/cappielloantonio/play/database/AppDatabase.java
index 903fd1e0..c38ee71d 100644
--- a/app/src/main/java/com/cappielloantonio/play/database/AppDatabase.java
+++ b/app/src/main/java/com/cappielloantonio/play/database/AppDatabase.java
@@ -3,7 +3,6 @@ package com.cappielloantonio.play.database;
 import android.annotation.SuppressLint;
 import android.content.Context;
 
-import androidx.room.AutoMigration;
 import androidx.room.Database;
 import androidx.room.Room;
 import androidx.room.RoomDatabase;
diff --git a/app/src/main/java/com/cappielloantonio/play/database/dao/ServerDao.java b/app/src/main/java/com/cappielloantonio/play/database/dao/ServerDao.java
index cff8d416..8ecc369e 100644
--- a/app/src/main/java/com/cappielloantonio/play/database/dao/ServerDao.java
+++ b/app/src/main/java/com/cappielloantonio/play/database/dao/ServerDao.java
@@ -7,7 +7,6 @@ import androidx.room.Insert;
 import androidx.room.OnConflictStrategy;
 import androidx.room.Query;
 
-import com.cappielloantonio.play.model.Queue;
 import com.cappielloantonio.play.model.Server;
 
 import java.util.List;
diff --git a/app/src/main/java/com/cappielloantonio/play/helper/recyclerview/GridItemDecoration.java b/app/src/main/java/com/cappielloantonio/play/helper/recyclerview/GridItemDecoration.java
index d7568366..f51ae5f2 100644
--- a/app/src/main/java/com/cappielloantonio/play/helper/recyclerview/GridItemDecoration.java
+++ b/app/src/main/java/com/cappielloantonio/play/helper/recyclerview/GridItemDecoration.java
@@ -3,6 +3,7 @@ package com.cappielloantonio.play.helper.recyclerview;
 import android.graphics.Rect;
 import android.view.View;
 
+import androidx.annotation.NonNull;
 import androidx.recyclerview.widget.RecyclerView;
 
 public class GridItemDecoration extends RecyclerView.ItemDecoration {
@@ -17,7 +18,7 @@ public class GridItemDecoration extends RecyclerView.ItemDecoration {
     }
 
     @Override
-    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
+    public void getItemOffsets(@NonNull Rect outRect, @NonNull View view, RecyclerView parent, @NonNull RecyclerView.State state) {
         int position = parent.getChildAdapterPosition(view); // item position
         int column = position % spanCount; // item column
 
diff --git a/app/src/main/java/com/cappielloantonio/play/model/Artist.java b/app/src/main/java/com/cappielloantonio/play/model/Artist.java
index d02de9ce..4138de5b 100644
--- a/app/src/main/java/com/cappielloantonio/play/model/Artist.java
+++ b/app/src/main/java/com/cappielloantonio/play/model/Artist.java
@@ -20,9 +20,7 @@ public class Artist implements Parcelable {
     public static final String DOWNLOADED = "DOWNLOADED";
     public static final String STARRED = "STARRED";
 
-    private List<Genre> genres;
     private List<Album> albums;
-    private List<Song> songs;
     private List<Artist> similarArtists;
 
     private String id;
@@ -222,9 +220,7 @@ public class Artist implements Parcelable {
     }
 
     protected Artist(Parcel in) {
-        this.genres = new ArrayList<>();
         this.albums = new ArrayList<>();
-        this.songs = new ArrayList<>();
         this.id = in.readString();
         this.name = in.readString();
         this.primary = in.readString();
diff --git a/app/src/main/java/com/cappielloantonio/play/model/Genre.java b/app/src/main/java/com/cappielloantonio/play/model/Genre.java
index 4de716ed..477754ab 100644
--- a/app/src/main/java/com/cappielloantonio/play/model/Genre.java
+++ b/app/src/main/java/com/cappielloantonio/play/model/Genre.java
@@ -22,14 +22,34 @@ public class Genre implements Parcelable {
         return id;
     }
 
+    public void setId(String id) {
+        this.id = id;
+    }
+
     public String getName() {
         return name;
     }
 
+    public void setName(String name) {
+        this.name = name;
+    }
+
     public int getSongCount() {
         return songCount;
     }
 
+    public void setSongCount(int songCount) {
+        this.songCount = songCount;
+    }
+
+    public int getAlbumCount() {
+        return albumCount;
+    }
+
+    public void setAlbumCount(int albumCount) {
+        this.albumCount = albumCount;
+    }
+
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;
diff --git a/app/src/main/java/com/cappielloantonio/play/model/Queue.java b/app/src/main/java/com/cappielloantonio/play/model/Queue.java
index 363f42d2..5245220a 100644
--- a/app/src/main/java/com/cappielloantonio/play/model/Queue.java
+++ b/app/src/main/java/com/cappielloantonio/play/model/Queue.java
@@ -1,13 +1,11 @@
 package com.cappielloantonio.play.model;
 
-import androidx.annotation.NonNull;
 import androidx.room.ColumnInfo;
 import androidx.room.Entity;
 import androidx.room.PrimaryKey;
 
 @Entity(tableName = "queue")
 public class Queue {
-    @NonNull
     @PrimaryKey
     @ColumnInfo(name = "track_order")
     private int trackOrder;
diff --git a/app/src/main/java/com/cappielloantonio/play/model/Server.java b/app/src/main/java/com/cappielloantonio/play/model/Server.java
index 26691b0d..8addd0fd 100644
--- a/app/src/main/java/com/cappielloantonio/play/model/Server.java
+++ b/app/src/main/java/com/cappielloantonio/play/model/Server.java
@@ -114,6 +114,7 @@ public class Server implements Parcelable {
         return serverId.hashCode();
     }
 
+    @NonNull
     @Override
     public String toString() {
         return serverId;
diff --git a/app/src/main/java/com/cappielloantonio/play/model/Song.java b/app/src/main/java/com/cappielloantonio/play/model/Song.java
index 7bddf66d..1d150470 100644
--- a/app/src/main/java/com/cappielloantonio/play/model/Song.java
+++ b/app/src/main/java/com/cappielloantonio/play/model/Song.java
@@ -3,6 +3,8 @@ package com.cappielloantonio.play.model;
 import android.os.Parcel;
 import android.os.Parcelable;
 
+import androidx.annotation.NonNull;
+
 import com.cappielloantonio.play.subsonic.models.Child;
 
 import java.time.Instant;
@@ -296,6 +298,7 @@ public class Song implements Parcelable {
         return id.hashCode();
     }
 
+    @NonNull
     @Override
     public String toString() {
         return id;
diff --git a/app/src/main/java/com/cappielloantonio/play/service/DownloadTracker.java b/app/src/main/java/com/cappielloantonio/play/service/DownloadTracker.java
index 145c84c3..77e93c37 100644
--- a/app/src/main/java/com/cappielloantonio/play/service/DownloadTracker.java
+++ b/app/src/main/java/com/cappielloantonio/play/service/DownloadTracker.java
@@ -1,5 +1,7 @@
 package com.cappielloantonio.play.service;
 
+import static com.google.android.exoplayer2.util.Assertions.checkNotNull;
+
 import android.content.Context;
 import android.net.Uri;
 
@@ -7,7 +9,6 @@ import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 
 import com.cappielloantonio.play.App;
-import com.cappielloantonio.play.model.Album;
 import com.cappielloantonio.play.model.Song;
 import com.cappielloantonio.play.repository.DownloadRepository;
 import com.cappielloantonio.play.util.MappingUtil;
@@ -29,8 +30,6 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.concurrent.CopyOnWriteArraySet;
 
-import static com.google.android.exoplayer2.util.Assertions.checkNotNull;
-
 public class DownloadTracker {
 
     private static final String TAG = "DownloadTracker";
@@ -74,7 +73,7 @@ public class DownloadTracker {
             MediaItem mediaItem = MusicUtil.getMediaItemFromSong(song);
             @Nullable Download download = downloads.get(checkNotNull(mediaItem.playbackProperties).uri);
 
-            if(download != null && download.state != Download.STATE_FAILED) {
+            if (download != null && download.state != Download.STATE_FAILED) {
                 return true;
             }
         }
@@ -91,7 +90,7 @@ public class DownloadTracker {
         DownloadRepository downloadRepository = new DownloadRepository(App.getInstance());
 
         for (Song song : songs) {
-            if(isDownloaded(song)) {
+            if (isDownloaded(song)) {
                 downloadRepository.insert(MappingUtil.mapToDownload(song, playlistId, playlistName));
                 continue;
             }
diff --git a/app/src/main/java/com/cappielloantonio/play/service/MusicService.java b/app/src/main/java/com/cappielloantonio/play/service/MusicService.java
index d56d0430..2d548834 100644
--- a/app/src/main/java/com/cappielloantonio/play/service/MusicService.java
+++ b/app/src/main/java/com/cappielloantonio/play/service/MusicService.java
@@ -6,12 +6,8 @@ import static com.google.android.exoplayer2.Player.MEDIA_ITEM_TRANSITION_REASON_
 import android.annotation.SuppressLint;
 import android.app.PendingIntent;
 import android.app.Service;
-import android.content.BroadcastReceiver;
 import android.content.ComponentName;
-import android.content.Context;
 import android.content.Intent;
-import android.content.IntentFilter;
-import android.media.AudioManager;
 import android.os.Binder;
 import android.os.Handler;
 import android.os.HandlerThread;
@@ -32,7 +28,6 @@ import com.cappielloantonio.play.R;
 import com.cappielloantonio.play.broadcast.receiver.MediaButtonIntentReceiver;
 import com.cappielloantonio.play.interfaces.Playback;
 import com.cappielloantonio.play.model.Playlist;
-import com.cappielloantonio.play.model.Queue;
 import com.cappielloantonio.play.model.Song;
 import com.cappielloantonio.play.repository.QueueRepository;
 import com.cappielloantonio.play.repository.SongRepository;
diff --git a/app/src/main/java/com/cappielloantonio/play/subsonic/Subsonic.java b/app/src/main/java/com/cappielloantonio/play/subsonic/Subsonic.java
index 1ab21b11..39b0c131 100644
--- a/app/src/main/java/com/cappielloantonio/play/subsonic/Subsonic.java
+++ b/app/src/main/java/com/cappielloantonio/play/subsonic/Subsonic.java
@@ -20,8 +20,8 @@ public class Subsonic {
 
     private final Context context;
 
-    private Version apiVersion = API_MAX_VERSION;
-    private SubsonicPreferences preferences;
+    private final Version apiVersion = API_MAX_VERSION;
+    private final SubsonicPreferences preferences;
 
     private SystemClient systemClient;
     private BrowsingClient browsingClient;
diff --git a/app/src/main/java/com/cappielloantonio/play/subsonic/base/Version.java b/app/src/main/java/com/cappielloantonio/play/subsonic/base/Version.java
index 45798a55..6bb1d19c 100644
--- a/app/src/main/java/com/cappielloantonio/play/subsonic/base/Version.java
+++ b/app/src/main/java/com/cappielloantonio/play/subsonic/base/Version.java
@@ -1,5 +1,7 @@
 package com.cappielloantonio.play.subsonic.base;
 
+import androidx.annotation.NonNull;
+
 public class Version implements Comparable<Version> {
 
     private static final String VERSION_PATTERN = "[0-9]+(\\.[0-9]+)*";
@@ -49,6 +51,7 @@ public class Version implements Comparable<Version> {
         return 0;
     }
 
+    @NonNull
     @Override
     public String toString() {
         return versionString;
diff --git a/app/src/main/java/com/cappielloantonio/play/subsonic/models/AlbumList.java b/app/src/main/java/com/cappielloantonio/play/subsonic/models/AlbumList.java
index 2f5a2945..64066da0 100644
--- a/app/src/main/java/com/cappielloantonio/play/subsonic/models/AlbumList.java
+++ b/app/src/main/java/com/cappielloantonio/play/subsonic/models/AlbumList.java
@@ -28,7 +28,7 @@ public class AlbumList {
      */
     public List<Child> getAlbums() {
         if (albums == null) {
-            albums = new ArrayList<Child>();
+            albums = new ArrayList<>();
         }
         return this.albums;
     }
diff --git a/app/src/main/java/com/cappielloantonio/play/subsonic/models/ArtistInfo.java b/app/src/main/java/com/cappielloantonio/play/subsonic/models/ArtistInfo.java
index b162f721..b16fc665 100644
--- a/app/src/main/java/com/cappielloantonio/play/subsonic/models/ArtistInfo.java
+++ b/app/src/main/java/com/cappielloantonio/play/subsonic/models/ArtistInfo.java
@@ -28,7 +28,7 @@ public class ArtistInfo extends ArtistInfoBase {
      */
     public List<Artist> getSimilarArtists() {
         if (similarArtists == null) {
-            similarArtists = new ArrayList<Artist>();
+            similarArtists = new ArrayList<>();
         }
         return this.similarArtists;
     }
diff --git a/app/src/main/java/com/cappielloantonio/play/subsonic/models/ArtistInfo2.java b/app/src/main/java/com/cappielloantonio/play/subsonic/models/ArtistInfo2.java
index b7f88ef8..bf423ceb 100644
--- a/app/src/main/java/com/cappielloantonio/play/subsonic/models/ArtistInfo2.java
+++ b/app/src/main/java/com/cappielloantonio/play/subsonic/models/ArtistInfo2.java
@@ -1,7 +1,6 @@
 package com.cappielloantonio.play.subsonic.models;
 
 import com.tickaroo.tikxml.annotation.Element;
-import com.tickaroo.tikxml.annotation.ElementNameMatcher;
 import com.tickaroo.tikxml.annotation.Xml;
 
 import java.util.ArrayList;
diff --git a/app/src/main/java/com/cappielloantonio/play/subsonic/models/Bookmarks.java b/app/src/main/java/com/cappielloantonio/play/subsonic/models/Bookmarks.java
index d259e43e..a2015d90 100644
--- a/app/src/main/java/com/cappielloantonio/play/subsonic/models/Bookmarks.java
+++ b/app/src/main/java/com/cappielloantonio/play/subsonic/models/Bookmarks.java
@@ -28,7 +28,7 @@ public class Bookmarks {
      */
     public List<Bookmark> getBookmarks() {
         if (bookmarks == null) {
-            bookmarks = new ArrayList<Bookmark>();
+            bookmarks = new ArrayList<>();
         }
         return this.bookmarks;
     }
diff --git a/app/src/main/java/com/cappielloantonio/play/subsonic/models/ChatMessages.java b/app/src/main/java/com/cappielloantonio/play/subsonic/models/ChatMessages.java
index 953c822a..e962695d 100644
--- a/app/src/main/java/com/cappielloantonio/play/subsonic/models/ChatMessages.java
+++ b/app/src/main/java/com/cappielloantonio/play/subsonic/models/ChatMessages.java
@@ -28,7 +28,7 @@ public class ChatMessages {
      */
     public List<ChatMessage> getChatMessages() {
         if (chatMessages == null) {
-            chatMessages = new ArrayList<ChatMessage>();
+            chatMessages = new ArrayList<>();
         }
         return this.chatMessages;
     }
diff --git a/app/src/main/java/com/cappielloantonio/play/subsonic/models/Directory.java b/app/src/main/java/com/cappielloantonio/play/subsonic/models/Directory.java
index 087852af..8b751702 100644
--- a/app/src/main/java/com/cappielloantonio/play/subsonic/models/Directory.java
+++ b/app/src/main/java/com/cappielloantonio/play/subsonic/models/Directory.java
@@ -36,7 +36,7 @@ public class Directory {
      */
     public List<Child> getchildren() {
         if (children == null) {
-            children = new ArrayList<Child>();
+            children = new ArrayList<>();
         }
         return this.children;
     }
diff --git a/app/src/main/java/com/cappielloantonio/play/subsonic/models/ErrorCode.java b/app/src/main/java/com/cappielloantonio/play/subsonic/models/ErrorCode.java
index 035a5818..b2f187f6 100644
--- a/app/src/main/java/com/cappielloantonio/play/subsonic/models/ErrorCode.java
+++ b/app/src/main/java/com/cappielloantonio/play/subsonic/models/ErrorCode.java
@@ -11,7 +11,7 @@ public class ErrorCode {
     public static int TRIAL_PERIOD_OVER = 60;
     public static int DATA_NOT_FOUND = 70;
 
-    private int value;
+    private final int value;
 
     public ErrorCode(int value) {
         this.value = value;
diff --git a/app/src/main/java/com/cappielloantonio/play/subsonic/models/Index.java b/app/src/main/java/com/cappielloantonio/play/subsonic/models/Index.java
index ba7dcbbc..b5a9ebf0 100644
--- a/app/src/main/java/com/cappielloantonio/play/subsonic/models/Index.java
+++ b/app/src/main/java/com/cappielloantonio/play/subsonic/models/Index.java
@@ -29,7 +29,7 @@ public class Index {
      */
     public List<Artist> getArtists() {
         if (artists == null) {
-            artists = new ArrayList<Artist>();
+            artists = new ArrayList<>();
         }
         return this.artists;
     }
diff --git a/app/src/main/java/com/cappielloantonio/play/subsonic/models/Indexes.java b/app/src/main/java/com/cappielloantonio/play/subsonic/models/Indexes.java
index 7ebdecc2..568396b7 100644
--- a/app/src/main/java/com/cappielloantonio/play/subsonic/models/Indexes.java
+++ b/app/src/main/java/com/cappielloantonio/play/subsonic/models/Indexes.java
@@ -32,7 +32,7 @@ public class Indexes {
      */
     public List<Artist> getShortcuts() {
         if (shortcuts == null) {
-            shortcuts = new ArrayList<Artist>();
+            shortcuts = new ArrayList<>();
         }
         return this.shortcuts;
     }
@@ -59,7 +59,7 @@ public class Indexes {
      */
     public List<Index> getIndices() {
         if (indices == null) {
-            indices = new ArrayList<Index>();
+            indices = new ArrayList<>();
         }
         return this.indices;
     }
@@ -86,7 +86,7 @@ public class Indexes {
      */
     public List<Child> getchildren() {
         if (children == null) {
-            children = new ArrayList<Child>();
+            children = new ArrayList<>();
         }
         return this.children;
     }
diff --git a/app/src/main/java/com/cappielloantonio/play/subsonic/models/InternetRadioStations.java b/app/src/main/java/com/cappielloantonio/play/subsonic/models/InternetRadioStations.java
index 926810f2..adf9159c 100644
--- a/app/src/main/java/com/cappielloantonio/play/subsonic/models/InternetRadioStations.java
+++ b/app/src/main/java/com/cappielloantonio/play/subsonic/models/InternetRadioStations.java
@@ -28,7 +28,7 @@ public class InternetRadioStations {
      */
     public List<InternetRadioStation> getInternetRadioStations() {
         if (internetRadioStations == null) {
-            internetRadioStations = new ArrayList<InternetRadioStation>();
+            internetRadioStations = new ArrayList<>();
         }
         return this.internetRadioStations;
     }
diff --git a/app/src/main/java/com/cappielloantonio/play/subsonic/models/JukeboxPlaylist.java b/app/src/main/java/com/cappielloantonio/play/subsonic/models/JukeboxPlaylist.java
index 005d7265..18c44b2c 100644
--- a/app/src/main/java/com/cappielloantonio/play/subsonic/models/JukeboxPlaylist.java
+++ b/app/src/main/java/com/cappielloantonio/play/subsonic/models/JukeboxPlaylist.java
@@ -28,7 +28,7 @@ public class JukeboxPlaylist extends JukeboxStatus {
      */
     public List<Child> getEntries() {
         if (entries == null) {
-            entries = new ArrayList<Child>();
+            entries = new ArrayList<>();
         }
         return this.entries;
     }
diff --git a/app/src/main/java/com/cappielloantonio/play/subsonic/models/NewestPodcasts.java b/app/src/main/java/com/cappielloantonio/play/subsonic/models/NewestPodcasts.java
index 771eab93..47f82216 100644
--- a/app/src/main/java/com/cappielloantonio/play/subsonic/models/NewestPodcasts.java
+++ b/app/src/main/java/com/cappielloantonio/play/subsonic/models/NewestPodcasts.java
@@ -28,7 +28,7 @@ public class NewestPodcasts {
      */
     public List<PodcastEpisode> getEpisodes() {
         if (episodes == null) {
-            episodes = new ArrayList<PodcastEpisode>();
+            episodes = new ArrayList<>();
         }
         return this.episodes;
     }
diff --git a/app/src/main/java/com/cappielloantonio/play/subsonic/models/NowPlaying.java b/app/src/main/java/com/cappielloantonio/play/subsonic/models/NowPlaying.java
index 803ac6a9..69dc7504 100644
--- a/app/src/main/java/com/cappielloantonio/play/subsonic/models/NowPlaying.java
+++ b/app/src/main/java/com/cappielloantonio/play/subsonic/models/NowPlaying.java
@@ -28,7 +28,7 @@ public class NowPlaying {
      */
     public List<NowPlayingEntry> getEntries() {
         if (entries == null) {
-            entries = new ArrayList<NowPlayingEntry>();
+            entries = new ArrayList<>();
         }
         return this.entries;
     }
diff --git a/app/src/main/java/com/cappielloantonio/play/subsonic/models/PlayQueue.java b/app/src/main/java/com/cappielloantonio/play/subsonic/models/PlayQueue.java
index b8cd892b..09cc643b 100644
--- a/app/src/main/java/com/cappielloantonio/play/subsonic/models/PlayQueue.java
+++ b/app/src/main/java/com/cappielloantonio/play/subsonic/models/PlayQueue.java
@@ -34,7 +34,7 @@ public class PlayQueue {
      */
     public List<Child> getEntries() {
         if (entries == null) {
-            entries = new ArrayList<Child>();
+            entries = new ArrayList<>();
         }
         return this.entries;
     }
diff --git a/app/src/main/java/com/cappielloantonio/play/subsonic/models/PodcastChannel.java b/app/src/main/java/com/cappielloantonio/play/subsonic/models/PodcastChannel.java
index f3d68c87..6af71073 100644
--- a/app/src/main/java/com/cappielloantonio/play/subsonic/models/PodcastChannel.java
+++ b/app/src/main/java/com/cappielloantonio/play/subsonic/models/PodcastChannel.java
@@ -36,7 +36,7 @@ public class PodcastChannel {
      */
     public List<PodcastEpisode> getEpisodes() {
         if (episodes == null) {
-            episodes = new ArrayList<PodcastEpisode>();
+            episodes = new ArrayList<>();
         }
         return this.episodes;
     }
diff --git a/app/src/main/java/com/cappielloantonio/play/subsonic/models/Podcasts.java b/app/src/main/java/com/cappielloantonio/play/subsonic/models/Podcasts.java
index 9fc2e47c..cf9a67a3 100644
--- a/app/src/main/java/com/cappielloantonio/play/subsonic/models/Podcasts.java
+++ b/app/src/main/java/com/cappielloantonio/play/subsonic/models/Podcasts.java
@@ -28,7 +28,7 @@ public class Podcasts {
      */
     public List<PodcastChannel> getChannels() {
         if (channels == null) {
-            channels = new ArrayList<PodcastChannel>();
+            channels = new ArrayList<>();
         }
         return this.channels;
     }
diff --git a/app/src/main/java/com/cappielloantonio/play/subsonic/models/ResponseStatus.java b/app/src/main/java/com/cappielloantonio/play/subsonic/models/ResponseStatus.java
index b0f67faf..a347a4b5 100644
--- a/app/src/main/java/com/cappielloantonio/play/subsonic/models/ResponseStatus.java
+++ b/app/src/main/java/com/cappielloantonio/play/subsonic/models/ResponseStatus.java
@@ -8,7 +8,7 @@ public class ResponseStatus {
     public static String OK = "ok";
     public static String FAILED = "failed";
 
-    private String value;
+    private final String value;
 
     public ResponseStatus(@Attribute String value) {
         this.value = value;
diff --git a/app/src/main/java/com/cappielloantonio/play/subsonic/models/SearchResult.java b/app/src/main/java/com/cappielloantonio/play/subsonic/models/SearchResult.java
index 88a14bb8..5528ea8c 100644
--- a/app/src/main/java/com/cappielloantonio/play/subsonic/models/SearchResult.java
+++ b/app/src/main/java/com/cappielloantonio/play/subsonic/models/SearchResult.java
@@ -30,7 +30,7 @@ public class SearchResult {
      */
     public List<Child> getMatches() {
         if (matches == null) {
-            matches = new ArrayList<Child>();
+            matches = new ArrayList<>();
         }
         return this.matches;
     }
diff --git a/app/src/main/java/com/cappielloantonio/play/subsonic/models/Share.java b/app/src/main/java/com/cappielloantonio/play/subsonic/models/Share.java
index 6f879578..c0861d71 100644
--- a/app/src/main/java/com/cappielloantonio/play/subsonic/models/Share.java
+++ b/app/src/main/java/com/cappielloantonio/play/subsonic/models/Share.java
@@ -37,7 +37,7 @@ public class Share {
      */
     public List<Child> getEntries() {
         if (entries == null) {
-            entries = new ArrayList<Child>();
+            entries = new ArrayList<>();
         }
         return this.entries;
     }
diff --git a/app/src/main/java/com/cappielloantonio/play/subsonic/models/Shares.java b/app/src/main/java/com/cappielloantonio/play/subsonic/models/Shares.java
index c17293e5..65ffc95b 100644
--- a/app/src/main/java/com/cappielloantonio/play/subsonic/models/Shares.java
+++ b/app/src/main/java/com/cappielloantonio/play/subsonic/models/Shares.java
@@ -28,7 +28,7 @@ public class Shares {
      */
     public List<Share> getShares() {
         if (shares == null) {
-            shares = new ArrayList<Share>();
+            shares = new ArrayList<>();
         }
         return this.shares;
     }
diff --git a/app/src/main/java/com/cappielloantonio/play/subsonic/models/SimilarArtistID3.java b/app/src/main/java/com/cappielloantonio/play/subsonic/models/SimilarArtistID3.java
index 2939ceb4..85f58df3 100644
--- a/app/src/main/java/com/cappielloantonio/play/subsonic/models/SimilarArtistID3.java
+++ b/app/src/main/java/com/cappielloantonio/play/subsonic/models/SimilarArtistID3.java
@@ -2,9 +2,6 @@ package com.cappielloantonio.play.subsonic.models;
 
 import com.tickaroo.tikxml.annotation.Attribute;
 import com.tickaroo.tikxml.annotation.Xml;
-import com.tickaroo.tikxml.converters.date.rfc3339.DateRfc3339TypeConverter;
-
-import java.util.Date;
 
 @Xml(name = "similarArtist")
 public class SimilarArtistID3 {
diff --git a/app/src/main/java/com/cappielloantonio/play/subsonic/models/SimilarSongs.java b/app/src/main/java/com/cappielloantonio/play/subsonic/models/SimilarSongs.java
index c2750fcc..ee676a99 100644
--- a/app/src/main/java/com/cappielloantonio/play/subsonic/models/SimilarSongs.java
+++ b/app/src/main/java/com/cappielloantonio/play/subsonic/models/SimilarSongs.java
@@ -28,7 +28,7 @@ public class SimilarSongs {
      */
     public List<Child> getSongs() {
         if (songs == null) {
-            songs = new ArrayList<Child>();
+            songs = new ArrayList<>();
         }
         return this.songs;
     }
diff --git a/app/src/main/java/com/cappielloantonio/play/subsonic/models/Starred.java b/app/src/main/java/com/cappielloantonio/play/subsonic/models/Starred.java
index 6f294bd9..dc456b65 100644
--- a/app/src/main/java/com/cappielloantonio/play/subsonic/models/Starred.java
+++ b/app/src/main/java/com/cappielloantonio/play/subsonic/models/Starred.java
@@ -30,7 +30,7 @@ public class Starred {
      */
     public List<Artist> getArtists() {
         if (artists == null) {
-            artists = new ArrayList<Artist>();
+            artists = new ArrayList<>();
         }
         return this.artists;
     }
@@ -57,7 +57,7 @@ public class Starred {
      */
     public List<Child> getAlbums() {
         if (albums == null) {
-            albums = new ArrayList<Child>();
+            albums = new ArrayList<>();
         }
         return this.albums;
     }
@@ -84,7 +84,7 @@ public class Starred {
      */
     public List<Child> getSongs() {
         if (songs == null) {
-            songs = new ArrayList<Child>();
+            songs = new ArrayList<>();
         }
         return this.songs;
     }
diff --git a/app/src/main/java/com/cappielloantonio/play/subsonic/models/User.java b/app/src/main/java/com/cappielloantonio/play/subsonic/models/User.java
index 54502759..c0d89f2e 100644
--- a/app/src/main/java/com/cappielloantonio/play/subsonic/models/User.java
+++ b/app/src/main/java/com/cappielloantonio/play/subsonic/models/User.java
@@ -46,7 +46,7 @@ public class User {
      */
     public List<Integer> getFolders() {
         if (folders == null) {
-            folders = new ArrayList<Integer>();
+            folders = new ArrayList<>();
         }
         return this.folders;
     }
diff --git a/app/src/main/java/com/cappielloantonio/play/subsonic/models/Users.java b/app/src/main/java/com/cappielloantonio/play/subsonic/models/Users.java
index 5adc4d83..6f923473 100644
--- a/app/src/main/java/com/cappielloantonio/play/subsonic/models/Users.java
+++ b/app/src/main/java/com/cappielloantonio/play/subsonic/models/Users.java
@@ -28,7 +28,7 @@ public class Users {
      */
     public List<User> getUsers() {
         if (users == null) {
-            users = new ArrayList<User>();
+            users = new ArrayList<>();
         }
         return this.users;
     }
diff --git a/app/src/main/java/com/cappielloantonio/play/subsonic/models/VideoInfo.java b/app/src/main/java/com/cappielloantonio/play/subsonic/models/VideoInfo.java
index c08efe95..fdb13acd 100644
--- a/app/src/main/java/com/cappielloantonio/play/subsonic/models/VideoInfo.java
+++ b/app/src/main/java/com/cappielloantonio/play/subsonic/models/VideoInfo.java
@@ -31,7 +31,7 @@ public class VideoInfo {
      */
     public List<Captions> getCaptions() {
         if (captions == null) {
-            captions = new ArrayList<Captions>();
+            captions = new ArrayList<>();
         }
         return this.captions;
     }
@@ -58,7 +58,7 @@ public class VideoInfo {
      */
     public List<AudioTrack> getAudioTracks() {
         if (audioTracks == null) {
-            audioTracks = new ArrayList<AudioTrack>();
+            audioTracks = new ArrayList<>();
         }
         return this.audioTracks;
     }
@@ -85,7 +85,7 @@ public class VideoInfo {
      */
     public List<VideoConversion> getConversions() {
         if (conversions == null) {
-            conversions = new ArrayList<VideoConversion>();
+            conversions = new ArrayList<>();
         }
         return this.conversions;
     }
diff --git a/app/src/main/java/com/cappielloantonio/play/subsonic/models/Videos.java b/app/src/main/java/com/cappielloantonio/play/subsonic/models/Videos.java
index 97ae528f..7524ca9d 100644
--- a/app/src/main/java/com/cappielloantonio/play/subsonic/models/Videos.java
+++ b/app/src/main/java/com/cappielloantonio/play/subsonic/models/Videos.java
@@ -28,7 +28,7 @@ public class Videos {
      */
     public List<Child> getVideos() {
         if (videos == null) {
-            videos = new ArrayList<Child>();
+            videos = new ArrayList<>();
         }
         return this.videos;
     }
diff --git a/app/src/main/java/com/cappielloantonio/play/subsonic/utils/StringUtil.java b/app/src/main/java/com/cappielloantonio/play/subsonic/utils/StringUtil.java
index 0cd2f236..7ef977de 100644
--- a/app/src/main/java/com/cappielloantonio/play/subsonic/utils/StringUtil.java
+++ b/app/src/main/java/com/cappielloantonio/play/subsonic/utils/StringUtil.java
@@ -9,13 +9,13 @@ public class StringUtil {
         try {
             MessageDigest digest = java.security.MessageDigest.getInstance(MD5);
             digest.update(s.getBytes());
-            byte messageDigest[] = digest.digest();
+            byte[] messageDigest = digest.digest();
 
             StringBuilder hexString = new StringBuilder();
             for (byte aMessageDigest : messageDigest) {
-                String h = Integer.toHexString(0xFF & aMessageDigest);
+                StringBuilder h = new StringBuilder(Integer.toHexString(0xFF & aMessageDigest));
                 while (h.length() < 2) {
-                    h = "0" + h;
+                    h.insert(0, "0");
                 }
                 hexString.append(h);
             }
diff --git a/app/src/main/java/com/cappielloantonio/play/subsonic/utils/converter/ErrorCodeConverter.java b/app/src/main/java/com/cappielloantonio/play/subsonic/utils/converter/ErrorCodeConverter.java
index 2511e0d4..b540e546 100644
--- a/app/src/main/java/com/cappielloantonio/play/subsonic/utils/converter/ErrorCodeConverter.java
+++ b/app/src/main/java/com/cappielloantonio/play/subsonic/utils/converter/ErrorCodeConverter.java
@@ -6,7 +6,7 @@ import com.tickaroo.tikxml.TypeConverter;
 public class ErrorCodeConverter implements TypeConverter<ErrorCode> {
     @Override
     public ErrorCode read(String value) throws Exception {
-        return new ErrorCode(Integer.valueOf(value));
+        return new ErrorCode(Integer.parseInt(value));
     }
 
     @Override
diff --git a/app/src/main/java/com/cappielloantonio/play/ui/fragment/AlbumCatalogueFragment.java b/app/src/main/java/com/cappielloantonio/play/ui/fragment/AlbumCatalogueFragment.java
index e71ee8b0..4c7f4571 100644
--- a/app/src/main/java/com/cappielloantonio/play/ui/fragment/AlbumCatalogueFragment.java
+++ b/app/src/main/java/com/cappielloantonio/play/ui/fragment/AlbumCatalogueFragment.java
@@ -107,9 +107,7 @@ public class AlbumCatalogueFragment extends Fragment {
         albumAdapter = new AlbumCatalogueAdapter(activity, requireContext());
         albumAdapter.setStateRestorationPolicy(RecyclerView.Adapter.StateRestorationPolicy.PREVENT_WHEN_EMPTY);
         bind.albumCatalogueRecyclerView.setAdapter(albumAdapter);
-        albumCatalogueViewModel.getAlbumList().observe(requireActivity(), albums -> {
-            albumAdapter.setItems(albums);
-        });
+        albumCatalogueViewModel.getAlbumList().observe(requireActivity(), albums -> albumAdapter.setItems(albums));
 
         bind.albumCatalogueRecyclerView.setOnTouchListener((v, event) -> {
             hideKeyboard(v);
diff --git a/app/src/main/java/com/cappielloantonio/play/ui/fragment/AlbumListPageFragment.java b/app/src/main/java/com/cappielloantonio/play/ui/fragment/AlbumListPageFragment.java
index 3336c6b1..0298c1aa 100644
--- a/app/src/main/java/com/cappielloantonio/play/ui/fragment/AlbumListPageFragment.java
+++ b/app/src/main/java/com/cappielloantonio/play/ui/fragment/AlbumListPageFragment.java
@@ -84,9 +84,7 @@ public class AlbumListPageFragment extends Fragment {
             activity.getSupportActionBar().setDisplayShowHomeEnabled(true);
         }
 
-        bind.toolbar.setNavigationOnClickListener(v -> {
-            activity.navController.navigateUp();
-        });
+        bind.toolbar.setNavigationOnClickListener(v -> activity.navController.navigateUp());
 
         bind.appBarLayout.addOnOffsetChangedListener((appBarLayout, verticalOffset) -> {
             if ((bind.albumInfoSector.getHeight() + verticalOffset) < (2 * ViewCompat.getMinimumHeight(bind.toolbar))) {
diff --git a/app/src/main/java/com/cappielloantonio/play/ui/fragment/AlbumPageFragment.java b/app/src/main/java/com/cappielloantonio/play/ui/fragment/AlbumPageFragment.java
index ba2b20aa..fda0c482 100644
--- a/app/src/main/java/com/cappielloantonio/play/ui/fragment/AlbumPageFragment.java
+++ b/app/src/main/java/com/cappielloantonio/play/ui/fragment/AlbumPageFragment.java
@@ -121,16 +121,14 @@ public class AlbumPageFragment extends Fragment {
     }
 
     private void initAlbumInfoTextButton() {
-        bind.albumArtistLabel.setOnClickListener(v -> {
-            albumPageViewModel.getArtist().observe(requireActivity(), artist -> {
-                if (artist != null) {
-                    Bundle bundle = new Bundle();
-                    bundle.putParcelable("artist_object", artist);
-                    activity.navController.navigate(R.id.action_albumPageFragment_to_artistPageFragment, bundle);
-                } else
-                    Toast.makeText(requireContext(), "Error retrieving artist", Toast.LENGTH_SHORT).show();
-            });
-        });
+        bind.albumArtistLabel.setOnClickListener(v -> albumPageViewModel.getArtist().observe(requireActivity(), artist -> {
+            if (artist != null) {
+                Bundle bundle = new Bundle();
+                bundle.putParcelable("artist_object", artist);
+                activity.navController.navigate(R.id.action_albumPageFragment_to_artistPageFragment, bundle);
+            } else
+                Toast.makeText(requireContext(), "Error retrieving artist", Toast.LENGTH_SHORT).show();
+        }));
     }
 
     private void initMusicButton() {
@@ -181,8 +179,6 @@ public class AlbumPageFragment extends Fragment {
         songHorizontalAdapter = new SongHorizontalAdapter(activity, requireContext(), false);
         bind.songRecyclerView.setAdapter(songHorizontalAdapter);
 
-        albumPageViewModel.getAlbumSongLiveList(requireActivity()).observe(requireActivity(), songs -> {
-            songHorizontalAdapter.setItems(songs);
-        });
+        albumPageViewModel.getAlbumSongLiveList(requireActivity()).observe(requireActivity(), songs -> songHorizontalAdapter.setItems(songs));
     }
 }
\ No newline at end of file
diff --git a/app/src/main/java/com/cappielloantonio/play/ui/fragment/ArtistCatalogueFragment.java b/app/src/main/java/com/cappielloantonio/play/ui/fragment/ArtistCatalogueFragment.java
index e9f60cb6..2b6b1336 100644
--- a/app/src/main/java/com/cappielloantonio/play/ui/fragment/ArtistCatalogueFragment.java
+++ b/app/src/main/java/com/cappielloantonio/play/ui/fragment/ArtistCatalogueFragment.java
@@ -107,9 +107,7 @@ public class ArtistCatalogueFragment extends Fragment {
         artistAdapter = new ArtistCatalogueAdapter(activity, requireContext());
         artistAdapter.setStateRestorationPolicy(RecyclerView.Adapter.StateRestorationPolicy.PREVENT_WHEN_EMPTY);
         bind.artistCatalogueRecyclerView.setAdapter(artistAdapter);
-        artistCatalogueViewModel.getArtistList().observe(requireActivity(), artistList -> {
-            artistAdapter.setItems(artistList);
-        });
+        artistCatalogueViewModel.getArtistList().observe(requireActivity(), artistList -> artistAdapter.setItems(artistList));
 
         bind.artistCatalogueRecyclerView.setOnTouchListener((v, event) -> {
             hideKeyboard(v);
diff --git a/app/src/main/java/com/cappielloantonio/play/ui/fragment/ArtistListPageFragment.java b/app/src/main/java/com/cappielloantonio/play/ui/fragment/ArtistListPageFragment.java
index 267dde8a..44d5d556 100644
--- a/app/src/main/java/com/cappielloantonio/play/ui/fragment/ArtistListPageFragment.java
+++ b/app/src/main/java/com/cappielloantonio/play/ui/fragment/ArtistListPageFragment.java
@@ -70,9 +70,7 @@ public class ArtistListPageFragment extends Fragment {
             activity.getSupportActionBar().setDisplayShowHomeEnabled(true);
         }
 
-        bind.toolbar.setNavigationOnClickListener(v -> {
-            activity.navController.navigateUp();
-        });
+        bind.toolbar.setNavigationOnClickListener(v -> activity.navController.navigateUp());
 
         bind.appBarLayout.addOnOffsetChangedListener((appBarLayout, verticalOffset) -> {
             if ((bind.artistInfoSector.getHeight() + verticalOffset) < (2 * ViewCompat.getMinimumHeight(bind.toolbar))) {
diff --git a/app/src/main/java/com/cappielloantonio/play/ui/fragment/FilterFragment.java b/app/src/main/java/com/cappielloantonio/play/ui/fragment/FilterFragment.java
index e5733dc6..11155714 100644
--- a/app/src/main/java/com/cappielloantonio/play/ui/fragment/FilterFragment.java
+++ b/app/src/main/java/com/cappielloantonio/play/ui/fragment/FilterFragment.java
@@ -1,7 +1,6 @@
 package com.cappielloantonio.play.ui.fragment;
 
 import android.os.Bundle;
-import android.text.Html;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
@@ -77,9 +76,7 @@ public class FilterFragment extends Fragment {
             activity.getSupportActionBar().setDisplayShowHomeEnabled(true);
         }
 
-        bind.toolbar.setNavigationOnClickListener(v -> {
-            activity.navController.navigateUp();
-        });
+        bind.toolbar.setNavigationOnClickListener(v -> activity.navController.navigateUp());
 
 
         bind.appBarLayout.addOnOffsetChangedListener((appBarLayout, verticalOffset) -> {
diff --git a/app/src/main/java/com/cappielloantonio/play/ui/fragment/GenreCatalogueFragment.java b/app/src/main/java/com/cappielloantonio/play/ui/fragment/GenreCatalogueFragment.java
index 571bf0cf..e0c524c0 100644
--- a/app/src/main/java/com/cappielloantonio/play/ui/fragment/GenreCatalogueFragment.java
+++ b/app/src/main/java/com/cappielloantonio/play/ui/fragment/GenreCatalogueFragment.java
@@ -114,9 +114,7 @@ public class GenreCatalogueFragment extends Fragment {
             activity.navController.navigate(R.id.action_genreCatalogueFragment_to_songListPageFragment, bundle);
         });
 
-        genreCatalogueViewModel.getGenreList().observe(requireActivity(), genres -> {
-            genreCatalogueAdapter.setItems(genres);
-        });
+        genreCatalogueViewModel.getGenreList().observe(requireActivity(), genres -> genreCatalogueAdapter.setItems(genres));
 
         bind.genreCatalogueRecyclerView.setOnTouchListener((v, event) -> {
             hideKeyboard(v);
diff --git a/app/src/main/java/com/cappielloantonio/play/ui/fragment/HomeFragment.java b/app/src/main/java/com/cappielloantonio/play/ui/fragment/HomeFragment.java
index 8f0064dc..27d35fc3 100644
--- a/app/src/main/java/com/cappielloantonio/play/ui/fragment/HomeFragment.java
+++ b/app/src/main/java/com/cappielloantonio/play/ui/fragment/HomeFragment.java
@@ -1,6 +1,5 @@
 package com.cappielloantonio.play.ui.fragment;
 
-import android.graphics.Color;
 import android.os.Bundle;
 import android.view.LayoutInflater;
 import android.view.Menu;
@@ -11,7 +10,6 @@ import android.view.ViewGroup;
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
-import androidx.core.content.ContextCompat;
 import androidx.core.view.ViewCompat;
 import androidx.fragment.app.Fragment;
 import androidx.lifecycle.ViewModelProvider;
@@ -27,8 +25,8 @@ import com.cappielloantonio.play.adapter.AlbumHorizontalAdapter;
 import com.cappielloantonio.play.adapter.ArtistHorizontalAdapter;
 import com.cappielloantonio.play.adapter.DiscoverSongAdapter;
 import com.cappielloantonio.play.adapter.SimilarTrackAdapter;
-import com.cappielloantonio.play.adapter.TrackAdapter;
 import com.cappielloantonio.play.adapter.SongHorizontalAdapter;
+import com.cappielloantonio.play.adapter.TrackAdapter;
 import com.cappielloantonio.play.adapter.YearAdapter;
 import com.cappielloantonio.play.databinding.FragmentHomeBinding;
 import com.cappielloantonio.play.helper.recyclerview.CustomLinearSnapHelper;
@@ -37,9 +35,6 @@ import com.cappielloantonio.play.model.Album;
 import com.cappielloantonio.play.model.Artist;
 import com.cappielloantonio.play.model.Song;
 import com.cappielloantonio.play.ui.activity.MainActivity;
-import com.cappielloantonio.play.util.DownloadUtil;
-import com.cappielloantonio.play.util.MappingUtil;
-import com.cappielloantonio.play.util.MusicUtil;
 import com.cappielloantonio.play.util.UIUtil;
 import com.cappielloantonio.play.viewmodel.HomeViewModel;
 
@@ -345,7 +340,8 @@ public class HomeFragment extends Fragment {
             } else {
                 if (bind != null) bind.homeStarredTracksPlaceholder.placeholder.setVisibility(View.GONE);
                 if (bind != null) bind.homeStarredTracksSector.setVisibility(!songs.isEmpty() ? View.VISIBLE : View.GONE);
-                if (bind != null) bind.starredTracksRecyclerView.setLayoutManager(new GridLayoutManager(requireContext(), UIUtil.getSpanCount(songs.size(), 5), GridLayoutManager.HORIZONTAL, false));
+                if (bind != null)
+                    bind.starredTracksRecyclerView.setLayoutManager(new GridLayoutManager(requireContext(), UIUtil.getSpanCount(songs.size(), 5), GridLayoutManager.HORIZONTAL, false));
 
                 starredSongAdapter.setItems(songs);
             }
@@ -376,7 +372,8 @@ public class HomeFragment extends Fragment {
             } else {
                 if (bind != null) bind.homeStarredAlbumsPlaceholder.placeholder.setVisibility(View.GONE);
                 if (bind != null) bind.homeStarredAlbumsSector.setVisibility(!albums.isEmpty() ? View.VISIBLE : View.GONE);
-                if (bind != null) bind.starredAlbumsRecyclerView.setLayoutManager(new GridLayoutManager(requireContext(), UIUtil.getSpanCount(albums.size(), 5), GridLayoutManager.HORIZONTAL, false));
+                if (bind != null)
+                    bind.starredAlbumsRecyclerView.setLayoutManager(new GridLayoutManager(requireContext(), UIUtil.getSpanCount(albums.size(), 5), GridLayoutManager.HORIZONTAL, false));
 
                 starredAlbumAdapter.setItems(albums);
             }
@@ -407,7 +404,8 @@ public class HomeFragment extends Fragment {
             } else {
                 if (bind != null) bind.homeStarredArtistsPlaceholder.placeholder.setVisibility(View.GONE);
                 if (bind != null) bind.homeStarredArtistsSector.setVisibility(!artists.isEmpty() ? View.VISIBLE : View.GONE);
-                if (bind != null) bind.starredArtistsRecyclerView.setLayoutManager(new GridLayoutManager(requireContext(), UIUtil.getSpanCount(artists.size(), 5), GridLayoutManager.HORIZONTAL, false));
+                if (bind != null)
+                    bind.starredArtistsRecyclerView.setLayoutManager(new GridLayoutManager(requireContext(), UIUtil.getSpanCount(artists.size(), 5), GridLayoutManager.HORIZONTAL, false));
 
                 starredArtistAdapter.setItems(artists);
             }
diff --git a/app/src/main/java/com/cappielloantonio/play/ui/fragment/LoginFragment.java b/app/src/main/java/com/cappielloantonio/play/ui/fragment/LoginFragment.java
index 9dcfb1f0..f32a70ff 100644
--- a/app/src/main/java/com/cappielloantonio/play/ui/fragment/LoginFragment.java
+++ b/app/src/main/java/com/cappielloantonio/play/ui/fragment/LoginFragment.java
@@ -1,6 +1,5 @@
 package com.cappielloantonio.play.ui.fragment;
 
-import android.graphics.Color;
 import android.os.Bundle;
 import android.view.LayoutInflater;
 import android.view.Menu;
@@ -14,9 +13,7 @@ import androidx.annotation.Nullable;
 import androidx.core.view.ViewCompat;
 import androidx.fragment.app.Fragment;
 import androidx.lifecycle.ViewModelProvider;
-import androidx.recyclerview.widget.ItemTouchHelper;
 import androidx.recyclerview.widget.LinearLayoutManager;
-import androidx.recyclerview.widget.RecyclerView;
 
 import com.cappielloantonio.play.R;
 import com.cappielloantonio.play.adapter.ServerAdapter;
@@ -25,8 +22,6 @@ import com.cappielloantonio.play.ui.activity.MainActivity;
 import com.cappielloantonio.play.ui.fragment.dialog.ServerSignupDialog;
 import com.cappielloantonio.play.viewmodel.LoginViewModel;
 
-import java.util.Collections;
-
 public class LoginFragment extends Fragment {
     private static final String TAG = "LoginFragment";
 
@@ -88,12 +83,11 @@ public class LoginFragment extends Fragment {
         serverAdapter = new ServerAdapter(activity, requireContext());
         bind.serverListRecyclerView.setAdapter(serverAdapter);
         loginViewModel.getServerList().observe(requireActivity(), servers -> {
-            if(servers.size() > 0) {
+            if (servers.size() > 0) {
                 if (bind != null) bind.noServerAddedTextView.setVisibility(View.GONE);
                 if (bind != null) bind.serverListRecyclerView.setVisibility(View.VISIBLE);
                 serverAdapter.setItems(servers);
-            }
-            else {
+            } else {
                 if (bind != null) bind.noServerAddedTextView.setVisibility(View.VISIBLE);
                 if (bind != null) bind.serverListRecyclerView.setVisibility(View.GONE);
             }
@@ -102,13 +96,10 @@ public class LoginFragment extends Fragment {
 
     @Override
     public boolean onOptionsItemSelected(@NonNull MenuItem item) {
-        switch (item.getItemId()) {
-            case R.id.action_add:
-                ServerSignupDialog dialog = new ServerSignupDialog();
-                dialog.show(activity.getSupportFragmentManager(), null);
-                return true;
-            default:
-                break;
+        if (item.getItemId() == R.id.action_add) {
+            ServerSignupDialog dialog = new ServerSignupDialog();
+            dialog.show(activity.getSupportFragmentManager(), null);
+            return true;
         }
 
         return false;
diff --git a/app/src/main/java/com/cappielloantonio/play/ui/fragment/PlayerBottomSheetFragment.java b/app/src/main/java/com/cappielloantonio/play/ui/fragment/PlayerBottomSheetFragment.java
index 3f12d2a1..d32a5ad0 100644
--- a/app/src/main/java/com/cappielloantonio/play/ui/fragment/PlayerBottomSheetFragment.java
+++ b/app/src/main/java/com/cappielloantonio/play/ui/fragment/PlayerBottomSheetFragment.java
@@ -37,6 +37,7 @@ import com.cappielloantonio.play.util.PreferenceUtil;
 import com.cappielloantonio.play.viewmodel.PlayerBottomSheetViewModel;
 
 import java.util.Collections;
+import java.util.Objects;
 
 public class PlayerBottomSheetFragment extends Fragment implements MusicServiceEventListener, MusicProgressViewUpdateHelper.Callback {
     private static final String TAG = "PlayerBottomSheetFragment";
@@ -166,7 +167,7 @@ public class PlayerBottomSheetFragment extends Fragment implements MusicServiceE
             int toPosition = -1;
 
             @Override
-            public boolean onMove(@NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
+            public boolean onMove(@NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder, @NonNull RecyclerView.ViewHolder target) {
                 if (originalPosition == -1)
                     originalPosition = viewHolder.getBindingAdapterPosition();
 
@@ -185,7 +186,7 @@ public class PlayerBottomSheetFragment extends Fragment implements MusicServiceE
                  */
 
                 Collections.swap(playerSongQueueAdapter.getItems(), fromPosition, toPosition);
-                recyclerView.getAdapter().notifyItemMoved(fromPosition, toPosition);
+                Objects.requireNonNull(recyclerView.getAdapter()).notifyItemMoved(fromPosition, toPosition);
 
                 return false;
             }
@@ -212,7 +213,7 @@ public class PlayerBottomSheetFragment extends Fragment implements MusicServiceE
                 if (!(viewHolder.getBindingAdapterPosition() == MusicPlayerRemote.getPosition()) && !(MusicPlayerRemote.getPlayingQueue().size() <= 1)) {
                     MusicPlayerRemote.removeFromQueue(viewHolder.getBindingAdapterPosition());
                     playerBottomSheetViewModel.removeSong(viewHolder.getBindingAdapterPosition());
-                    bodyBind.playerQueueRecyclerView.getAdapter().notifyItemRemoved(viewHolder.getBindingAdapterPosition());
+                    Objects.requireNonNull(bodyBind.playerQueueRecyclerView.getAdapter()).notifyItemRemoved(viewHolder.getBindingAdapterPosition());
                     bodyBind.playerSongCoverViewPager.setCurrentItem(MusicPlayerRemote.getPosition(), false);
                 } else {
                     bodyBind.playerQueueRecyclerView.getAdapter().notifyDataSetChanged();
@@ -271,11 +272,6 @@ public class PlayerBottomSheetFragment extends Fragment implements MusicServiceE
     }
 
     private void setViewPageDelayed(int position) {
-        /*bodyBind.playerSongCoverViewPager.post(() -> {
-            int restoredPosition = PreferenceManager.getDefaultSharedPreferences(requireContext()).getInt(PreferenceUtil.POSITION, -1);
-            bodyBind.playerSongCoverViewPager.setCurrentItem(restoredPosition, true);
-        });*/
-
         final Handler handler = new Handler();
         final Runnable r = () -> {
             if (bind != null) bodyBind.playerSongCoverViewPager.setCurrentItem(position, false);
@@ -308,7 +304,7 @@ public class PlayerBottomSheetFragment extends Fragment implements MusicServiceE
     }
 
     public View getPlayerHeader() {
-        return getView().findViewById(R.id.player_header_layout);
+        return requireView().findViewById(R.id.player_header_layout);
     }
 
     public void scrollOnTop() {
@@ -322,7 +318,7 @@ public class PlayerBottomSheetFragment extends Fragment implements MusicServiceE
 
     @Override
     public void onServiceConnected() {
-        setSongInfo(MusicPlayerRemote.getCurrentSong());
+        setSongInfo(Objects.requireNonNull(MusicPlayerRemote.getCurrentSong()));
         updatePlayPauseState();
     }
 
@@ -339,7 +335,7 @@ public class PlayerBottomSheetFragment extends Fragment implements MusicServiceE
     @Override
     public void onPlayMetadataChanged() {
         setViewPageDelayed(MusicPlayerRemote.getPosition());
-        setSongInfo(MusicPlayerRemote.getCurrentSong());
+        setSongInfo(Objects.requireNonNull(MusicPlayerRemote.getCurrentSong()));
     }
 
     @Override
diff --git a/app/src/main/java/com/cappielloantonio/play/ui/fragment/PlaylistCatalogueFragment.java b/app/src/main/java/com/cappielloantonio/play/ui/fragment/PlaylistCatalogueFragment.java
index cdde347d..333ea8b7 100644
--- a/app/src/main/java/com/cappielloantonio/play/ui/fragment/PlaylistCatalogueFragment.java
+++ b/app/src/main/java/com/cappielloantonio/play/ui/fragment/PlaylistCatalogueFragment.java
@@ -107,9 +107,7 @@ public class PlaylistCatalogueFragment extends Fragment {
 
         playlistCatalogueAdapter = new PlaylistCatalogueAdapter(activity, requireContext(), playlistCatalogueViewModel.getType().equals(Playlist.DOWNLOADED));
         bind.playlistCatalogueRecyclerView.setAdapter(playlistCatalogueAdapter);
-        playlistCatalogueViewModel.getPlaylistList(requireActivity()).observe(requireActivity(), playlist -> {
-            playlistCatalogueAdapter.setItems(playlist);
-        });
+        playlistCatalogueViewModel.getPlaylistList(requireActivity()).observe(requireActivity(), playlist -> playlistCatalogueAdapter.setItems(playlist));
 
         bind.playlistCatalogueRecyclerView.setOnTouchListener((v, event) -> {
             hideKeyboard(v);
diff --git a/app/src/main/java/com/cappielloantonio/play/ui/fragment/bottomsheetdialog/SongBottomSheetDialog.java b/app/src/main/java/com/cappielloantonio/play/ui/fragment/bottomsheetdialog/SongBottomSheetDialog.java
index 6a23fb65..de160b42 100644
--- a/app/src/main/java/com/cappielloantonio/play/ui/fragment/bottomsheetdialog/SongBottomSheetDialog.java
+++ b/app/src/main/java/com/cappielloantonio/play/ui/fragment/bottomsheetdialog/SongBottomSheetDialog.java
@@ -33,6 +33,7 @@ import com.google.android.material.bottomsheet.BottomSheetDialogFragment;
 
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 
 public class SongBottomSheetDialog extends BottomSheetDialogFragment implements View.OnClickListener {
@@ -146,13 +147,13 @@ public class SongBottomSheetDialog extends BottomSheetDialogFragment implements
 
         TextView download = view.findViewById(R.id.download_text_view);
         download.setOnClickListener(v -> {
-            DownloadUtil.getDownloadTracker(requireContext()).download(Arrays.asList(song), null, null);
+            DownloadUtil.getDownloadTracker(requireContext()).download(Collections.singletonList(song), null, null);
             dismissBottomSheet();
         });
 
         TextView remove = view.findViewById(R.id.remove_text_view);
         remove.setOnClickListener(v -> {
-            DownloadUtil.getDownloadTracker(requireContext()).remove(Arrays.asList(song));
+            DownloadUtil.getDownloadTracker(requireContext()).remove(Collections.singletonList(song));
             dismissBottomSheet();
         });
 
@@ -171,32 +172,28 @@ public class SongBottomSheetDialog extends BottomSheetDialogFragment implements
         });
 
         TextView goToAlbum = view.findViewById(R.id.go_to_album_text_view);
-        goToAlbum.setOnClickListener(v -> {
-            songBottomSheetViewModel.getAlbum().observe(requireActivity(), album -> {
-                if (album != null) {
-                    Bundle bundle = new Bundle();
-                    bundle.putParcelable("album_object", album);
-                    NavHostFragment.findNavController(this).navigate(R.id.albumPageFragment, bundle);
-                } else
-                    Toast.makeText(requireContext(), "Error retrieving album", Toast.LENGTH_SHORT).show();
+        goToAlbum.setOnClickListener(v -> songBottomSheetViewModel.getAlbum().observe(requireActivity(), album -> {
+            if (album != null) {
+                Bundle bundle = new Bundle();
+                bundle.putParcelable("album_object", album);
+                NavHostFragment.findNavController(this).navigate(R.id.albumPageFragment, bundle);
+            } else
+                Toast.makeText(requireContext(), "Error retrieving album", Toast.LENGTH_SHORT).show();
 
-                dismissBottomSheet();
-            });
-        });
+            dismissBottomSheet();
+        }));
 
         TextView goToArtist = view.findViewById(R.id.go_to_artist_text_view);
-        goToArtist.setOnClickListener(v -> {
-            songBottomSheetViewModel.getArtist().observe(requireActivity(), artist -> {
-                if (artist != null) {
-                    Bundle bundle = new Bundle();
-                    bundle.putParcelable("artist_object", artist);
-                    NavHostFragment.findNavController(this).navigate(R.id.artistPageFragment, bundle);
-                } else
-                    Toast.makeText(requireContext(), "Error retrieving artist", Toast.LENGTH_SHORT).show();
+        goToArtist.setOnClickListener(v -> songBottomSheetViewModel.getArtist().observe(requireActivity(), artist -> {
+            if (artist != null) {
+                Bundle bundle = new Bundle();
+                bundle.putParcelable("artist_object", artist);
+                NavHostFragment.findNavController(this).navigate(R.id.artistPageFragment, bundle);
+            } else
+                Toast.makeText(requireContext(), "Error retrieving artist", Toast.LENGTH_SHORT).show();
 
-                dismissBottomSheet();
-            });
-        });
+            dismissBottomSheet();
+        }));
     }
 
     @Override
diff --git a/app/src/main/java/com/cappielloantonio/play/ui/fragment/dialog/PlaylistEditorDialog.java b/app/src/main/java/com/cappielloantonio/play/ui/fragment/dialog/PlaylistEditorDialog.java
index 3bd4f5b5..2562bf92 100644
--- a/app/src/main/java/com/cappielloantonio/play/ui/fragment/dialog/PlaylistEditorDialog.java
+++ b/app/src/main/java/com/cappielloantonio/play/ui/fragment/dialog/PlaylistEditorDialog.java
@@ -108,9 +108,7 @@ public class PlaylistEditorDialog extends DialogFragment {
         playlistDialogSongHorizontalAdapter = new PlaylistDialogSongHorizontalAdapter(requireContext());
         bind.playlistSongRecyclerView.setAdapter(playlistDialogSongHorizontalAdapter);
 
-        playlistEditorViewModel.getPlaylistSongLiveList().observe(requireActivity(), songs -> {
-            playlistDialogSongHorizontalAdapter.setItems(songs);
-        });
+        playlistEditorViewModel.getPlaylistSongLiveList().observe(requireActivity(), songs -> playlistDialogSongHorizontalAdapter.setItems(songs));
 
         new ItemTouchHelper(new ItemTouchHelper.SimpleCallback(ItemTouchHelper.UP | ItemTouchHelper.DOWN, ItemTouchHelper.LEFT) {
             int originalPosition = -1;
@@ -118,7 +116,7 @@ public class PlaylistEditorDialog extends DialogFragment {
             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, @NonNull RecyclerView.ViewHolder target) {
                 if (originalPosition == -1)
                     originalPosition = viewHolder.getBindingAdapterPosition();
 
@@ -147,16 +145,16 @@ public class PlaylistEditorDialog extends DialogFragment {
             }
 
             @Override
-            public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {
+            public void onSwiped(@NonNull RecyclerView.ViewHolder viewHolder, int direction) {
                 playlistEditorViewModel.removeFromPlaylistSongLiveList(viewHolder.getBindingAdapterPosition());
-                bind.playlistSongRecyclerView.getAdapter().notifyItemRemoved(viewHolder.getBindingAdapterPosition());
+                Objects.requireNonNull(bind.playlistSongRecyclerView.getAdapter()).notifyItemRemoved(viewHolder.getBindingAdapterPosition());
             }
         }
         ).attachToRecyclerView(bind.playlistSongRecyclerView);
     }
 
     private boolean validateInput() {
-        playlistName = bind.playlistNameTextView.getText().toString().trim();
+        playlistName = Objects.requireNonNull(bind.playlistNameTextView.getText()).toString().trim();
 
         if (TextUtils.isEmpty(playlistName)) {
             bind.playlistNameTextView.setError("Required");
diff --git a/app/src/main/java/com/cappielloantonio/play/ui/fragment/dialog/RatingDialog.java b/app/src/main/java/com/cappielloantonio/play/ui/fragment/dialog/RatingDialog.java
index 1dd65b02..35f6fbb6 100644
--- a/app/src/main/java/com/cappielloantonio/play/ui/fragment/dialog/RatingDialog.java
+++ b/app/src/main/java/com/cappielloantonio/play/ui/fragment/dialog/RatingDialog.java
@@ -32,9 +32,7 @@ public class RatingDialog extends DialogFragment {
         builder.setView(bind.getRoot())
                 .setTitle("Rate")
                 .setNegativeButton("Cancel", (dialog, id) -> dialog.cancel())
-                .setPositiveButton("Save", (dialog, id) -> {
-                    ratingViewModel.rate((int) bind.ratingBar.getRating());
-                });
+                .setPositiveButton("Save", (dialog, id) -> ratingViewModel.rate((int) bind.ratingBar.getRating()));
 
         return builder.create();
     }
diff --git a/app/src/main/java/com/cappielloantonio/play/util/MappingUtil.java b/app/src/main/java/com/cappielloantonio/play/util/MappingUtil.java
index cd270d54..bae19b33 100644
--- a/app/src/main/java/com/cappielloantonio/play/util/MappingUtil.java
+++ b/app/src/main/java/com/cappielloantonio/play/util/MappingUtil.java
@@ -17,9 +17,7 @@ import com.cappielloantonio.play.subsonic.models.Genre;
 import com.cappielloantonio.play.subsonic.models.SimilarArtistID3;
 
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.List;
-import java.util.stream.Collectors;
 
 public class MappingUtil {
     public static ArrayList<Song> mapSong(List<Child> children) {
@@ -111,7 +109,7 @@ public class MappingUtil {
 
         for (Download download : downloads) {
             Song song = new Song(download);
-            if(!songs.contains(song)) {
+            if (!songs.contains(song)) {
                 songs.add(song);
             }
         }
@@ -124,7 +122,7 @@ public class MappingUtil {
 
         for (Download download : downloads) {
             Album album = new Album(download);
-            if(!albums.contains(album)) {
+            if (!albums.contains(album)) {
                 albums.add(album);
             }
         }
@@ -137,7 +135,7 @@ public class MappingUtil {
 
         for (Download download : downloads) {
             Artist artist = new Artist(download);
-            if(!artists.contains(artist)) {
+            if (!artists.contains(artist)) {
                 artists.add(artist);
             }
         }
diff --git a/app/src/main/java/com/cappielloantonio/play/util/MusicUtil.java b/app/src/main/java/com/cappielloantonio/play/util/MusicUtil.java
index c7ccabbd..434309d5 100644
--- a/app/src/main/java/com/cappielloantonio/play/util/MusicUtil.java
+++ b/app/src/main/java/com/cappielloantonio/play/util/MusicUtil.java
@@ -9,11 +9,9 @@ import com.cappielloantonio.play.model.Song;
 import com.google.android.exoplayer2.MediaItem;
 
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
-import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
 public class MusicUtil {
@@ -76,8 +74,8 @@ public class MusicUtil {
 
     public static String normalizedArtistName(String string) {
         if (string != null) {
-            if(string.toLowerCase().contains(" feat.")) return Pattern.compile(" feat.", Pattern.CASE_INSENSITIVE).split(string)[0].trim();
-            else if(string.toLowerCase().contains(" featuring")) return Pattern.compile(" featuring", Pattern.CASE_INSENSITIVE).split(string)[0].trim();
+            if (string.toLowerCase().contains(" feat.")) return Pattern.compile(" feat.", Pattern.CASE_INSENSITIVE).split(string)[0].trim();
+            else if (string.toLowerCase().contains(" featuring")) return Pattern.compile(" featuring", Pattern.CASE_INSENSITIVE).split(string)[0].trim();
             else return string;
         }
 
diff --git a/app/src/main/java/com/cappielloantonio/play/viewmodel/PlaylistCatalogueViewModel.java b/app/src/main/java/com/cappielloantonio/play/viewmodel/PlaylistCatalogueViewModel.java
index 835bda2b..0a360251 100644
--- a/app/src/main/java/com/cappielloantonio/play/viewmodel/PlaylistCatalogueViewModel.java
+++ b/app/src/main/java/com/cappielloantonio/play/viewmodel/PlaylistCatalogueViewModel.java
@@ -8,7 +8,6 @@ import androidx.lifecycle.AndroidViewModel;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 
-import com.cappielloantonio.play.model.Album;
 import com.cappielloantonio.play.model.Playlist;
 import com.cappielloantonio.play.repository.DownloadRepository;
 import com.cappielloantonio.play.repository.PlaylistRepository;
diff --git a/app/src/main/java/com/cappielloantonio/play/viewmodel/PlaylistPageViewModel.java b/app/src/main/java/com/cappielloantonio/play/viewmodel/PlaylistPageViewModel.java
index 5b8f58e4..d6511f37 100644
--- a/app/src/main/java/com/cappielloantonio/play/viewmodel/PlaylistPageViewModel.java
+++ b/app/src/main/java/com/cappielloantonio/play/viewmodel/PlaylistPageViewModel.java
@@ -8,7 +8,6 @@ import androidx.lifecycle.AndroidViewModel;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 
-import com.cappielloantonio.play.model.Album;
 import com.cappielloantonio.play.model.Playlist;
 import com.cappielloantonio.play.model.Song;
 import com.cappielloantonio.play.repository.DownloadRepository;
@@ -36,8 +35,7 @@ public class PlaylistPageViewModel extends AndroidViewModel {
     public LiveData<List<Song>> getPlaylistSongLiveList(FragmentActivity activity) {
         if (isOffline) {
             downloadRepository.getLiveDownloadFromPlaylist(playlist.getId()).observe(activity, downloads -> playlistSongLiveList.postValue(MappingUtil.mapDownloadToSong(downloads)));
-        }
-        else {
+        } else {
             playlistSongLiveList = playlistRepository.getPlaylistSongs(playlist.getId());
         }
 
diff --git a/app/src/main/java/com/cappielloantonio/play/viewmodel/SongListPageViewModel.java b/app/src/main/java/com/cappielloantonio/play/viewmodel/SongListPageViewModel.java
index 74d75bd4..6b8cbeea 100644
--- a/app/src/main/java/com/cappielloantonio/play/viewmodel/SongListPageViewModel.java
+++ b/app/src/main/java/com/cappielloantonio/play/viewmodel/SongListPageViewModel.java
@@ -75,14 +75,10 @@ public class SongListPageViewModel extends AndroidViewModel {
                 songList = songRepository.getStarredSongs(false, -1);
                 break;
             case Song.DOWNLOADED:
-                downloadRepository.getLiveDownload().observe(activity, downloads -> {
-                    songList.setValue(MappingUtil.mapDownloadToSong(downloads));
-                });
+                downloadRepository.getLiveDownload().observe(activity, downloads -> songList.setValue(MappingUtil.mapDownloadToSong(downloads)));
                 break;
             case Song.FROM_ALBUM:
-                downloadRepository.getLiveDownloadFromAlbum(album.getId()).observe(activity, downloads -> {
-                    songList.setValue(MappingUtil.mapDownloadToSong(downloads));
-                });
+                downloadRepository.getLiveDownloadFromAlbum(album.getId()).observe(activity, downloads -> songList.setValue(MappingUtil.mapDownloadToSong(downloads)));
                 break;
         }