Question 1

What are the three basic components of the Room library and what is the role of each?

Accepted Answer

Entity represents database tables and their columns, DAO defines the query and insert operations, and RoomDatabase is the central access point for the connection.

Question 2

Why is it recommended to move from SharedPreferences to Jetpack DataStore?

Accepted Answer

Because DataStore is completely thread-safe, relies on Kotlin coroutines and Flow, and handles errors safely without blocking the UI or causing ANR errors.

Question 3

How do you store custom data types (such as dates or lists) in Room using TypeConverters?

Accepted Answer

By defining functions annotated with @TypeConverter to convert the custom type to a primitive type SQLite understands (such as text or a number) and reverse it on read.

Question 4

How do you handle upgrading the database schema (Room database migrations) without losing user data?

Accepted Answer

By increasing the version number and writing a Migration object that runs the appropriate ALTER TABLE statements, or relying on AutoMigration if the change is simple.

Question 5

How do you design relationships between tables (one-to-many and many-to-many) in Room?

Accepted Answer

Using intermediary data objects with the @Embedded and @Relation annotations to specify the foreign key and primary key without complicating queries by hand.

Question 6

What is the difference between Preferences DataStore and Proto DataStore and when do you choose Proto DataStore?

Accepted Answer

Preferences DataStore stores key-value pairs with no predefined schema; Proto DataStore stores custom objects with strict, safe data types using Protocol Buffers.