Convert the abstract class DAOs to interfaces.

app/src/main/java/org/schabi/newpipe/database/playlist/dao/PlaylistDAO.java

@@ -14,26 +14,26 @@ import static org.schabi.newpipe.database.playlist.model.PlaylistEntity.PLAYLIST
 import static org.schabi.newpipe.database.playlist.model.PlaylistEntity.PLAYLIST_TABLE;
 
 @Dao
-public abstract class PlaylistDAO implements BasicDAO<PlaylistEntity> {
+public interface PlaylistDAO extends BasicDAO<PlaylistEntity> {
     @Override
     @Query("SELECT * FROM " + PLAYLIST_TABLE)
-    public abstract Flowable<List<PlaylistEntity>> getAll();
+    Flowable<List<PlaylistEntity>> getAll();
 
     @Override
     @Query("DELETE FROM " + PLAYLIST_TABLE)
-    public abstract int deleteAll();
+    int deleteAll();
 
     @Override
-    public Flowable<List<PlaylistEntity>> listByService(final int serviceId) {
+    default Flowable<List<PlaylistEntity>> listByService(final int serviceId) {
         throw new UnsupportedOperationException();
     }
 
     @Query("SELECT * FROM " + PLAYLIST_TABLE + " WHERE " + PLAYLIST_ID + " = :playlistId")
-    public abstract Flowable<List<PlaylistEntity>> getPlaylist(long playlistId);
+    Flowable<List<PlaylistEntity>> getPlaylist(long playlistId);
 
     @Query("DELETE FROM " + PLAYLIST_TABLE + " WHERE " + PLAYLIST_ID + " = :playlistId")
-    public abstract int deletePlaylist(long playlistId);
+    int deletePlaylist(long playlistId);
 
     @Query("SELECT COUNT(*) FROM " + PLAYLIST_TABLE)
-    public abstract Flowable<Long> getCount();
+    Flowable<Long> getCount();
 }

app/src/main/java/org/schabi/newpipe/database/playlist/dao/PlaylistRemoteDAO.java

@@ -17,31 +17,31 @@ import static org.schabi.newpipe.database.playlist.model.PlaylistRemoteEntity.RE
 import static org.schabi.newpipe.database.playlist.model.PlaylistRemoteEntity.REMOTE_PLAYLIST_URL;
 
 @Dao
-public abstract class PlaylistRemoteDAO implements BasicDAO<PlaylistRemoteEntity> {
+public interface PlaylistRemoteDAO extends BasicDAO<PlaylistRemoteEntity> {
     @Override
     @Query("SELECT * FROM " + REMOTE_PLAYLIST_TABLE)
-    public abstract Flowable<List<PlaylistRemoteEntity>> getAll();
+    Flowable<List<PlaylistRemoteEntity>> getAll();
 
     @Override
     @Query("DELETE FROM " + REMOTE_PLAYLIST_TABLE)
-    public abstract int deleteAll();
+    int deleteAll();
 
     @Override
     @Query("SELECT * FROM " + REMOTE_PLAYLIST_TABLE
             + " WHERE " + REMOTE_PLAYLIST_SERVICE_ID + " = :serviceId")
-    public abstract Flowable<List<PlaylistRemoteEntity>> listByService(int serviceId);
+    Flowable<List<PlaylistRemoteEntity>> listByService(int serviceId);
 
     @Query("SELECT * FROM " + REMOTE_PLAYLIST_TABLE + " WHERE "
             + REMOTE_PLAYLIST_URL + " = :url AND " + REMOTE_PLAYLIST_SERVICE_ID + " = :serviceId")
-    public abstract Flowable<List<PlaylistRemoteEntity>> getPlaylist(long serviceId, String url);
+    Flowable<List<PlaylistRemoteEntity>> getPlaylist(long serviceId, String url);
 
     @Query("SELECT " + REMOTE_PLAYLIST_ID + " FROM " + REMOTE_PLAYLIST_TABLE
             + " WHERE " + REMOTE_PLAYLIST_URL + " = :url "
             + "AND " + REMOTE_PLAYLIST_SERVICE_ID + " = :serviceId")
-    abstract Long getPlaylistIdInternal(long serviceId, String url);
+    Long getPlaylistIdInternal(long serviceId, String url);
 
     @Transaction
-    public long upsert(final PlaylistRemoteEntity playlist) {
+    default long upsert(final PlaylistRemoteEntity playlist) {
         final Long playlistId = getPlaylistIdInternal(playlist.getServiceId(), playlist.getUrl());
 
         if (playlistId == null) {
@@ -55,5 +55,5 @@ public abstract class PlaylistRemoteDAO implements BasicDAO<PlaylistRemoteEntity
 
     @Query("DELETE FROM " + REMOTE_PLAYLIST_TABLE
             + " WHERE " + REMOTE_PLAYLIST_ID + " = :playlistId")
-    public abstract int deletePlaylist(long playlistId);
+    int deletePlaylist(long playlistId);
 }

app/src/main/java/org/schabi/newpipe/database/playlist/dao/PlaylistStreamDAO.java

@@ -29,28 +29,28 @@ import static org.schabi.newpipe.database.stream.model.StreamStateEntity.STREAM_
 import static org.schabi.newpipe.database.stream.model.StreamStateEntity.STREAM_STATE_TABLE;
 
 @Dao
-public abstract class PlaylistStreamDAO implements BasicDAO<PlaylistStreamEntity> {
+public interface PlaylistStreamDAO extends BasicDAO<PlaylistStreamEntity> {
     @Override
     @Query("SELECT * FROM " + PLAYLIST_STREAM_JOIN_TABLE)
-    public abstract Flowable<List<PlaylistStreamEntity>> getAll();
+    Flowable<List<PlaylistStreamEntity>> getAll();
 
     @Override
     @Query("DELETE FROM " + PLAYLIST_STREAM_JOIN_TABLE)
-    public abstract int deleteAll();
+    int deleteAll();
 
     @Override
-    public Flowable<List<PlaylistStreamEntity>> listByService(final int serviceId) {
+    default Flowable<List<PlaylistStreamEntity>> listByService(final int serviceId) {
         throw new UnsupportedOperationException();
     }
 
     @Query("DELETE FROM " + PLAYLIST_STREAM_JOIN_TABLE
             + " WHERE " + JOIN_PLAYLIST_ID + " = :playlistId")
-    public abstract void deleteBatch(long playlistId);
+    void deleteBatch(long playlistId);
 
     @Query("SELECT COALESCE(MAX(" + JOIN_INDEX + "), -1)"
             + " FROM " + PLAYLIST_STREAM_JOIN_TABLE
             + " WHERE " + JOIN_PLAYLIST_ID + " = :playlistId")
-    public abstract Flowable<Integer> getMaximumIndexOf(long playlistId);
+    Flowable<Integer> getMaximumIndexOf(long playlistId);
 
     @Transaction
     @Query("SELECT * FROM " + STREAM_TABLE + " INNER JOIN "
@@ -69,7 +69,7 @@ public abstract class PlaylistStreamDAO implements BasicDAO<PlaylistStreamEntity
             + " ON " + STREAM_ID + " = " + JOIN_STREAM_ID_ALIAS
 
             + " ORDER BY " + JOIN_INDEX + " ASC")
-    public abstract Flowable<List<PlaylistStreamEntry>> getOrderedStreamsOf(long playlistId);
+    Flowable<List<PlaylistStreamEntry>> getOrderedStreamsOf(long playlistId);
 
     @Transaction
     @Query("SELECT " + PLAYLIST_ID + ", " + PLAYLIST_NAME + ", " + PLAYLIST_THUMBNAIL_URL + ", "
@@ -80,5 +80,5 @@ public abstract class PlaylistStreamDAO implements BasicDAO<PlaylistStreamEntity
             + " ON " + PLAYLIST_ID + " = " + JOIN_PLAYLIST_ID
             + " GROUP BY " + JOIN_PLAYLIST_ID
             + " ORDER BY " + PLAYLIST_NAME + " COLLATE NOCASE ASC")
-    public abstract Flowable<List<PlaylistMetadataEntry>> getPlaylistMetadata();
+    Flowable<List<PlaylistMetadataEntry>> getPlaylistMetadata();
 }

app/src/main/java/org/schabi/newpipe/database/stream/dao/StreamStateDAO.java

@@ -17,31 +17,31 @@ import static org.schabi.newpipe.database.stream.model.StreamStateEntity.JOIN_ST
 import static org.schabi.newpipe.database.stream.model.StreamStateEntity.STREAM_STATE_TABLE;
 
 @Dao
-public abstract class StreamStateDAO implements BasicDAO<StreamStateEntity> {
+public interface StreamStateDAO extends BasicDAO<StreamStateEntity> {
     @Override
     @Query("SELECT * FROM " + STREAM_STATE_TABLE)
-    public abstract Flowable<List<StreamStateEntity>> getAll();
+    Flowable<List<StreamStateEntity>> getAll();
 
     @Override
     @Query("DELETE FROM " + STREAM_STATE_TABLE)
-    public abstract int deleteAll();
+    int deleteAll();
 
     @Override
-    public Flowable<List<StreamStateEntity>> listByService(final int serviceId) {
+    default Flowable<List<StreamStateEntity>> listByService(final int serviceId) {
         throw new UnsupportedOperationException();
     }
 
     @Query("SELECT * FROM " + STREAM_STATE_TABLE + " WHERE " + JOIN_STREAM_ID + " = :streamId")
-    public abstract Flowable<List<StreamStateEntity>> getState(long streamId);
+    Flowable<List<StreamStateEntity>> getState(long streamId);
 
     @Query("DELETE FROM " + STREAM_STATE_TABLE + " WHERE " + JOIN_STREAM_ID + " = :streamId")
-    public abstract int deleteState(long streamId);
+    int deleteState(long streamId);
 
     @Insert(onConflict = OnConflictStrategy.IGNORE)
-    abstract void silentInsertInternal(StreamStateEntity streamState);
+    void silentInsertInternal(StreamStateEntity streamState);
 
     @Transaction
-    public long upsert(final StreamStateEntity stream) {
+    default long upsert(final StreamStateEntity stream) {
         silentInsertInternal(stream);
         return update(stream);
     }