我有一个名为"countries"的MySQL表，结构如下：

有一个实体叫做"customCountry"：
```java
@Entity
@Table(name="countries")
public class customCountry {
    @Id
    @Column(name = "id", table ="countries")
    private Long id;
    @Column(name = "code", table ="countries")
    private Long code;
    @Column(name = "language", table ="countries")
    private String language;
    // 构造函数 + getter/setter
}

@Repository
public interface customCountryRepository extends JpaRepository<customCountry, Long>{
    List<customCountry> findAll();
}

@Service
@ComponentScan(basePackages="repository")
public class countriesService {
    @Autowired
    customCountryRepository customcountry_repo;
    
    public List<customCountry> loadcustomcountries() {
        List<customCountry> validcustomcountries = customcountry_repo.findAll();
        System.out.println("size: " + validcustomcountries.size());
        return validcustomcountries;
    }
}

<details>
<summary>英文:</summary>
i have a mysql table &quot;countries&quot; as follow 

this entity "customCountry":

@Column(name = "code",table ="countries")
 private Long code;
@Column(name = "language",table ="countries")
 private String language;

i have this repository :

List<customCountry> findAll();

and this service class :

@Autowired
customCountryRepository customcountry_repo;
public List<customCountry> loadcustomcountries()
{
	List<customCountry> validcustomcountries = customcountry_repo.findAll();
	System.out.println("size: "+validcustomcountries.size());
	return validcustomcountries;
}

the problem is that when i called this service method in my controller , i find out that the size = 0 , but i don't see why , i think that i well managed the mapping between attributes and columns though .
thank you
</details>
# 答案1
**得分**: 0
你可以从仓库类中移除 **`List&lt;customCountry&gt; findAll();`**。
因为你已经扩展了 **`JpaRepository&lt;customCountry,Long&gt;`**，它已经有了这个方法。
尽管你在仓库中提供了这个方法，但没有实现它。
这可能会导致问题。
试试移除它看看。
<details>
<summary>英文:</summary>
You can remove  **`List&lt;customCountry&gt; findAll();`** from repository class.
As you had already extended **`JpaRepository&lt;customCountry,Long&gt;`**, it&#39;s have this method.
As you are providing that method in repository but not implementation of it.
That is causing an issue.
Just try by removing it.
</details>