Answer to Lukeberry Pi's challenge https://twitter.com/LukeberryPi/status/1625543309459439625

LongestCommonPrefix.java

import java.util.stream.Collectors;
import java.util.stream.Stream;

public class LongestCommonPrefix {
        static final Holder FIRST_HOLDER = new Holder("", 0) {
                @Override
                Holder acc(String another) {
                        return another.isEmpty()? EMPTY_HOLDER: new Holder(another);
                }
                @Override
                Holder acc(Holder another) {
                        return another;
                }
        };

        static final Holder EMPTY_HOLDER = new Holder("", 0) {
                @Override
                Holder acc(String another) {
                        return this;
                }
                @Override
                Holder acc(Holder another) {
                        return this;
                }
        };

        static class Holder {
                final String prefix;
                final int len;

                Holder(String prefix) {
                        this(prefix, prefix.length());
                }

                Holder(String prefix, int len) {
                        this.prefix = prefix;
                        this.len = len;
                }

                Holder acc(String another) {
                        return acc(another, another.length());
                }

                Holder acc(Holder another) {
                        if (another == FIRST_HOLDER) {
                                return this;
                        }
                        return acc(another.prefix, another.len);
                }
                private Holder acc(String another, int anotherLen) {
                        int x = anotherLen <= len? anotherLen: len;
                        for (int i = 0; i < x; i++) {
                                if (prefix.charAt(i) != another.charAt(i)) {
                                        if (i == 0) {
                                                return EMPTY_HOLDER;
                                        }
                                        return new Holder(another, i);
                                }
                        }
                        return new Holder(another, x);
                }

                String prefix() {
                        return prefix.substring(0, len);
                }
        }

        private static String prefix(String[] args) {
                return Stream.of(args)
                        .parallel()
                        .reduce(FIRST_HOLDER, Holder::acc, Holder::acc)
                        .prefix();
        }

        public static void main(String... args) {
                System.out.println(prefix(args));
        }
}