Issue
I am using Room architecture component for persistence. I have created generic DAO interface to avoid boilerplate code. Room Pro Tips
But my code doesn't compile saying "Error:(21, 19) error: Type of the parameter must be a class annotated with @Entity or a collection/array of it." for the Generic class T.
interface BaseDao<T> {
@Insert(onConflict = OnConflictStrategy.REPLACE)
void insert(T... entity);
@Update
void update(T entity);
@Delete
void delete(T entity);
}
@Dao
public abstract class ReasonDao implements BaseDao<ReasonDao> {
@Query("SELECT * from Reason")
abstract public List<Reason> getReasons();
}
Is there anything I am missing here. It works like this here
Solution
I had initially followed the method used in Kotlin, but that gives the error in Java code. Two quick changes fixed it for me
- Change BaseDao to Abstract class
- Added @Dao annotation to the BaseDao
Please find the code below and now it runs properly
@Dao
abstract class BaseDao<T> {
@Insert(onConflict = OnConflictStrategy.REPLACE)
abstract void insert(T entity);
@Update
abstract void update(T entity);
@Delete
abstract void delete(T entity);
}
@Dao
public abstract class ReasonDao extends BaseDao<Reason>{
@Query("SELECT * from Reason")
abstract public List<Reason> getReasons();
}
Answered By - xrnd
Answer Checked By - Mary Flores (JavaFixing Volunteer)