public class PersonService {
    public PersonCategorized getCategorizedPerson(List<Person> allPersonFromDb) {
        List<Person> adultList = allPersonFromDb.stream().filter(PersonUtil::isAdult).collect(Collectors.toList());
        List<Person> underAgedList = allPersonFromDb.stream().filter(PersonUtil::isUnderAged).collect(Collectors.toList());
        List<Person> seniorCitizenList = allPersonFromDb.stream().filter(PersonUtil::isSeniorCitizen).collect(Collectors.toList());

        return new PersonCategorized(underAgedList, adultList, seniorCitizenList);
    }
}

public class PersonCategorized {
    private List<Person> underAgedPersonList;
    private List<Person> adultList;
    private List<Person> seniorCitizenList;

    public PersonCategorized(List<Person> underAgedPersonList, List<Person> adultList, List<Person> seniorCitizenList) {
        this.underAgedPersonList = underAgedPersonList;
        this.adultList = adultList;
        this.seniorCitizenList = seniorCitizenList;
    }

    public List<Person> getAdultList() {
        return adultList;
    }

    public List<Person> getSeniorCitizenList() {
        return seniorCitizenList;
    }

    public List<Person> getUnderAgedPersonList() {
        return underAgedPersonList;
    }
}

public class Person {
    private int age;
    private String name;

    public Person(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public int getAge() {
        return age;
    }

    public String getName() {
        return name;
    }
}

public class PersonUtil {
    public static boolean isAdult(Person person) {
        return person.getAge() >= 18 && person.getAge() < 60;
    }

    public static boolean isUnderAged(Person person) {
        return person.getAge() >= 0 && person.getAge() < 18;
    }

    public static boolean isSeniorCitizen(Person person) {
        return person.getAge() >= 0 && person.getAge() < 18;
    }
}