对于库模块中定义的 POJO 的 @NonNull 注释构造函数参数，Android Room @Embedded 注释编译失败

Question

我有一个 POJO，我正在将其嵌入到房间实体中；请注意，POJO 是在库模块中定义的；

@Entity
public class Person {
    @PrimaryKey
    @NonNull
    private String uuid;

    @Embedded
    @NonNull
    private Address address;

    public Person(@NonNull String uuid, @NonNull Address address) {
        this.uuid = uuid;
        this.address = address;
    }

    @NonNull
    public String getUuid() {
        return uuid;
    }

    @NonNull
    public Address getAddress() {
        return address;
    }
}


public class Address {
    @NonNull
    private String street;

    @NonNull
    private String city;

    public Address(@NonNull String street, @NonNull String city) {
        this.street = street;
        this.city = city;
    }

    @NonNull
    public String getStreet() {
        return street;
    }

    @NonNull
    public String getCity() {
        return city;
    }
}


@Dao
public interface PersonDao {
    @Query("SELECT * FROM Person")
    List<Person> getPersons();
}



@TypeConverters(DateConverter.class)
@Database(entities = {Person.class}, version = 1, exportSchema = false)
public abstract class PersonDb extends RoomDatabase {
    private static volatile PersonDb INSTANCE;

    public abstract PersonDao getPersonDao();
}

编译失败

"Error:Entities and Pojos must have a usable public constructor. You can have an empty constructor or a constructor whose parameters match the fields (by name and type)." Error:Cannot find setter for field.

如果我从构造函数参数中删除 @NonNull 注释到 Address POJO，代码可以正常编译。此外，如果相同的 POJO 在应用程序模块中，代码会编译。

可以看出，Address 类确实有一个公共(public)构造函数。

我在这里错过了什么？从 Room 的角度来看，可用构造函数 的定义是什么？还是 Room 的问题？

Answer 1

文档说:"To persist a field, Room must have access to it. You can make a field public, or you can provide a getter and setter for it. If you use getter and setter methods, keep in mind that they're based on JavaBeans conventions in Room. "

uuid 和 address 在 Person 中被声明为 private，你有这些的 getter 但没有 setter。因此，您可以创建 setter 或将它们声明为 public。