question: public static List < Episode > returnNewEpisodes ( Context context , Channel channel , List < Episode > newEpisodeList ) { List < Episode > newEpisodes = new ArrayList < > ( ) ; List < Episode > existingEpisodeList = getEpisodesByChannel ( context , channel ) ; Map < String , Episode > existingEpisodeMap = new ArrayMap < > ( existingEpisodeList . size ( ) ) ; for ( int i = 0 ; i < existingEpisodeList . size ( ) ; i ++ ) { Episode episode = existingEpisodeList . get ( i ) ; existingEpisodeMap . put ( episode . getGeneratedId ( ) , episode ) ; } for ( int i = 0 ; i < newEpisodeList . size ( ) ; i ++ ) { Episode episode = newEpisodeList . get ( i ) ; if ( ! existingEpisodeMap . containsKey ( episode . getGeneratedId ( ) ) ) { newEpisodes . add ( episode ) ; } } return newEpisodes ; }
target:  Returns episodes that aren't in the episodeList but are in the database