Why does Java compiler complain when I use Comparator.comparingand thenCompare

Question

I have a Person class that has 2 fields, one is name, and the other is age, I would like to sort by age first and then by name.

Simple code is as follows:

import java.util.ArrayList;
import java.util.List;

public class Person {
    public String getName() {
        return name;
    }

    public int getAge() {
        return age;
    }

    @Override
    public String toString() {
        return "Person{" + "name='" + name + '\'' + ", age=" + age + '}';
    }

    String name;
    int age;


    public static List<Person> getPersons() {
        List<Person> persons = new ArrayList<>();
        Person p1 = new Person();
        p1.name = "Jack";
        p1.age = 29;
        persons.add(p1);

        p1 = new Person();
        p1.name = "Tom";
        p1.age = 27;
        persons.add(p1);

        p1 = new Person();
        p1.name = "Don";
        p1.age = 27;
        persons.add(p1);

        return persons;
    }

}

Test code is:

    @Test
    public void testComparator() {
        List<Person> persons = Person.getPersons();
        persons.sort(Comparator.comparing(p->p.getAge()).thenComparing(p->p.getName()));
        System.out.println(persons);
    }

It complains that getAge and getName are not methods of Object, I would ask where the problem is.