Shift GPS timestamp in nmea

FixGPS.java

import java.io.BufferedReader;
import java.io.IOException;
import java.io.Writer;
import java.nio.file.Files;
import java.nio.file.Path;
import java.time.Duration;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.format.DateTimeFormatter;

public class FixGPS {

    static String sample = """
                    @Sonygps/ver5.0/wgs-84/20210718015210.000/
                    @Sonygpsoption/0/20210718015213.000/20210718015212.544/
                    $GPGGA,015212.544,3326.5546,N,13031.8540,E,1,0,,,M,,M,,*7D
                    $GPRMC,015212.544,A,3326.5546,N,13031.8540,E,0.31,,180721,,,A*70
                    """;
    
    public static void main(String args[]) throws IOException {
        var org = Path.of("V:\\as100\\PRIVATE\\SONY\\GPS\\21071801.LOG");
        var fix = Path.of("V:\\as100\\PRIVATE\\SONY\\GPS\\21071801fix.nmea");

        try (var r = Files.newBufferedReader(org);
             var w = Files.newBufferedWriter(fix)) {
            var d = Duration.ofMinutes(23).plusSeconds(37);
            convert(r, w, d);
        }
    }

    static void convert(BufferedReader br, Writer out, Duration d) throws IOException {
        
        var top = br.readLine();
        var strs = top.split("/");
        dateTimePlus(strs, 3, d);
        out.write(String.join("/", strs) + "/\r\n");
        
        var sec = br.readLine();
        strs = sec.split("/");
        dateTimePlus(strs, 2, d);
        dateTimePlus(strs, 3, d);
        out.write(String.join("/", strs) + "/\r\n");
        
        for (String line; (line = br.readLine()) != null; ) {
            strs = line.split(",");
            timePlus(strs, 1, d);
            out.write(String.join(",", strs) + "\r\n");
        }
    }
    
    static void dateTimePlus(String[] strs, int index, Duration d) {
        var pat = DateTimeFormatter.ofPattern("yyyyMMddHHmmss.SSS");
        var dt = LocalDateTime.parse(strs[index], pat);
        strs[index] = pat.format(dt.plus(d));
    }
    static void timePlus(String[] strs, int index, Duration d) {
        var pat = DateTimeFormatter.ofPattern("HHmmss.SSS");
        var t = LocalTime.parse(strs[index], pat);
        strs[index] = pat.format(t.plus(d));
    }
}