Android Development Android Data Storage 2

Question 1

Which Room annotation defines a foreign key relationship between two entities?

Accepted Answer

@ForeignKey inside @Entity

Answer

The @ForeignKey annotation within @Entity defines referential integrity constraints between two Room database tables.

Question 2

How do you perform a database migration in Room when the schema changes?

Accepted Answer

By providing a Migration object with SQL migration scripts

Answer

Room requires you to provide a Migration object containing the SQL statements needed to transform the old schema to the new one.

Question 3

What return type should a Room DAO method use to observe database changes reactively?

Accepted Answer

Both A and B

Answer

Room supports both Flow and LiveData as return types for DAO queries, enabling reactive observation of database changes.

Question 4

Which method is used to get or create an instance of a Room database?

Accepted Answer

Room.databaseBuilder()

Answer

Room.databaseBuilder() creates or opens a Room database with the specified context, class, and database name.

Question 5

What is the purpose of the @TypeConverter annotation in Room?

Accepted Answer

To convert non-primitive types that Room cannot store natively

Answer

@TypeConverter marks methods that tell Room how to convert a custom type to and from a type it can store in SQLite.

Android Development Practice Test