The method findOne(Long) is undefined for the type PersonRepository

I am trying to build simple blog app with Spring boot.However, now I am facing an issue with "The method findOne(Long) is undefined for the type PersonRepository" when I try to use findOne for my service.java.Below are what I did

I tried to create objects in repository indicating findOne and save.However it didn't help

PersonRepository.java

package PersonRepository.javaio.javabrains.repository;

import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;

import io.javabrains.Entity.Person;
@Repository
public interface PersonRepository extends CrudRepository<Person,Long>{

public Person findByEmail(String email);

    /*
     * public Person findOne(Long id);
     * 
     * public Iterable<Person> findAll();
     * 
     * public Person save(Person person);
     */

PersonService.java

@Service
public class PersonService {

    @Autowired
    private PersonRepository personRepository;

    public Object findAll(){
        return personRepository.findAll();
    }

    public Person findById(Long id){
        return personRepository.findOne(id);
    }

I expected eliminating comment blocks would solve the issue.However, when I try to run the app ,it shows an error