question: public Storage ( File directory , String propertiesFile ) { if ( directory == null ) throw new NullPointerException ( "Directory cannot be null" ) ; if ( directory . isFile ( ) ) throw new IllegalArgumentException ( "Not a valid directory: " + directory ) ; this . directory = directory ; this . propertiesFile = propertiesFile != null ? new File ( directory , propertiesFile ) : null ; }
target:  Creates new instance of Storage.