Person OOP

          // file App.java

package personoop;

import java.time.LocalDate;

public class App {
        public static void testPerson(Person[] people, LocalDate now) {
        Object[] sortedByAge = Person.sortByAge(people);
        printResult(sortedByAge);

        Object[] filteredAndSorted = Person.filterOver18AndSortByLastNameAndAge(people, now);
        printResult(filteredAndSorted);
    }

    private static void printResult(Object[] sortedPeople) {
        StringBuilder result = new StringBuilder();
        for (Object person : sortedPeople) {
            result.append(person.toString());
            result.append(",");
        }
        result.deleteCharAt(result.length() - 1);
        System.out.println(result);
    }
}

          // file Person.java

package personoop;

import java.time.LocalDate;
import java.time.Period;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;

public class Person {
    private final String id;
    private final LocalDate birthdate;
    private final String firstName;
    private final String lastName;

    public Person(String id, LocalDate birthdate, String firstName, String lastName) {
        this.id = id;
        this.birthdate = birthdate;
        this.firstName = firstName;
        this.lastName = lastName;
    }

    public String getLastName() {
        return lastName;
    }

    public int getAge() {
        Period period = Period.between(this.birthdate, LocalDate.now());
        return period.getYears();
    }

    public int getAge(LocalDate date) {
        Period period = Period.between(this.birthdate, date);
        return period.getYears();
    }

    public static Object[] sortByAge(Person[] people) {
        return Arrays.stream(people)
                .sorted(Collections.reverseOrder(Comparator.comparingInt(Person::getAge)))
                .toArray();
    }

    public static Object[] filterOver18AndSortByLastNameAndAge(Person[] people, LocalDate date) {
        return Arrays.stream(people)
                .filter(person -> person.getAge(date) >= 18)
                .sorted(Comparator.comparing(Person::getLastName).reversed()
                        .thenComparing(person -> person.getAge(date)).reversed())
                .toArray();
    }

    @Override
    public String toString() {
        return String.format("(%s,%s,%s,%d)",this.id, this.firstName, this.lastName, getAge());
    }
}