question: public static String formatFileSize ( int bytes ) { if ( bytes <= 0 ) return null ; if ( bytes < 1024 ) { return bytes + "B" ; } else if ( bytes < 1024 * 1024 ) { return String . format ( "%.1f KB" , bytes / 1024.0 ) ; } else if ( bytes < 1024 * 1024 * 1024 ) { return String . format ( "%.1f MB" , bytes / ( 1024.0 * 1024.0 ) ) ; } else { return String . format ( "%.1f GB" , bytes / ( 1024.0 * 1024.0 * 1024.0 ) ) ; } }
target:  Formats a file size, ISO prefixes