question: public boolean addGpsDateTimeStampTag ( long timestamp ) { ExifTag t = buildTag ( TAG_GPS_DATE_STAMP , mGPSDateStampFormat . format ( timestamp ) ) ; if ( t == null ) { return false ; } setTag ( t ) ; mGPSTimeStampCalendar . setTimeInMillis ( timestamp ) ; t = buildTag ( TAG_GPS_TIME_STAMP , new Rational [ ] { new Rational ( mGPSTimeStampCalendar . get ( Calendar . HOUR_OF_DAY ) , 1 ) , new Rational ( mGPSTimeStampCalendar . get ( Calendar . MINUTE ) , 1 ) , new Rational ( mGPSTimeStampCalendar . get ( Calendar . SECOND ) , 1 ) } ) ; if ( t == null ) { return false ; } setTag ( t ) ; return true ; }
target:  Creates and sets the GPS timestamp tag.