I need to implement a method which should take an array of persons, basically public String oldest (Person [] persons), and return the oldest one. The persons which will be inputed are the following:

new Person("Augusta Ada King, grevinna av Lovelace", 1815),
new Person("Muhammad ibn Musa al-Khwarizmi", 780),
new Person("Alan Turing", 1912),
new Person("Grace Hopper", 1906)

Below you can find my class Called Person. I've tried all different solutions with basic for-loop but I feel really lost and would appreciate any input or recommendation how I should write the method to find the oldest person.

class Person {

String name;
int yearOfBirth;

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

public int getAge() {
return getAge(java.time.LocalDate.now().getYear());
}

public int getAge(int year) {
return year - yearOfBirth;
}

@Override
public String toString() {
return String.format("%s %d", name, yearOfBirth);
}

public String oldest(Person [] persons){
 
}

CodePudding user response：

You can try this:

Person oldest = Arrays.stream(persons).max(Comparator.comparing(Person::getAge)).get();

CodePudding user response：

You need to iterate over your persons array and check which yearOfBirth is greater. You can implement your method like below:

public String oldest(Person[] persons) {
        Person oldestPerson = persons[0];
        for (Person person : persons) {
            if (person.getYearOfBirth() < oldestPerson.getYearOfBirth()) {
                oldestPerson = person;
            }
        }
        return oldestPerson.getName();
    }

CodePudding user response：

1. This method should be static since it has nothing to do with an instance, and otherwise you have to call the method from an instance, which you probably don't want to do

2. Want should happen if you have more then one (oldest) person with the same age?

3. Why should the return be only the name and not a Person?

    public static String oldest(Person[] persons) {
        if (persons == null){
            throw new NullPointerException("persons == null");
        }
        if (persons.length == 0) {
            return null; //or throw same Exception depending on your handling
        }
   
        Person oldestPerson = persons[0];
        for (Person person : persons) {
            if (person.yearOfBirth < oldestPerson.yearOfBirth) {
                oldestPerson = person;
            }
        }
        return oldestPerson.name;
    }