Entity, DAO, Database classes in Android Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a Room entity with a primary key.

Android Kotlin

import androidx.room.Entity
import androidx.room.PrimaryKey

@Entity
 data class User(
    @PrimaryKey val [1]: Int,
    val name: String
)

Drag options to blanks, or click blank then click option'

Akey

BuserId

Cuid

Did

Attempts:

3 left

💡 Hint

Common Mistakes

Using a field name that is not descriptive or conventional for primary keys.

The primary key field is commonly named id to uniquely identify each entity instance.

2fill in blank

medium

Complete the DAO interface method to get all users from the database.

Android Kotlin

import androidx.room.Dao
import androidx.room.Query

@Dao
interface UserDao {
    @Query("SELECT * FROM User")
    fun [1](): List<User>
}

Drag options to blanks, or click blank then click option'

AgetAllUsers

BfetchUsers

CloadAll

DretrieveUsers

Attempts:

3 left

💡 Hint

Common Mistakes

Using vague method names that do not clearly indicate the action.

The method name getAllUsers clearly describes the action of retrieving all user records.

3fill in blank

hard

Fix the error in the database class declaration by completing the annotation.

Android Kotlin

import androidx.room.Database
import androidx.room.RoomDatabase

@Database(entities = [User::class], version = [1])
abstract class AppDatabase : RoomDatabase() {
    abstract fun userDao(): UserDao
}

Drag options to blanks, or click blank then click option'

A-1

B1

C0

Dnull

Attempts:

3 left

💡 Hint

Common Mistakes

Setting the version to zero or negative values causes runtime errors.

The database version must be a positive integer starting at 1 to manage schema versions properly.

4fill in blank

hard

Fill both blanks to define a DAO method that inserts a user and returns the new row ID.

Android Kotlin

import androidx.room.Dao
import androidx.room.Insert

@Dao
interface UserDao {
    @Insert
    fun [1](user: User): [2]
}

Drag options to blanks, or click blank then click option'

AinsertUser

BLong

CInt

DaddUser

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect return types like Int or void for insert methods.

The method name insertUser clearly states the action, and the return type Long represents the new row ID.

5fill in blank

hard

Fill all three blanks to define a Room database class with entities, version, and an abstract DAO method.

Android Kotlin

import androidx.room.Database
import androidx.room.RoomDatabase

@Database(entities = [[1]::class], version = [2])
abstract class [3] : RoomDatabase() {
    abstract fun userDao(): UserDao
}

Drag options to blanks, or click blank then click option'

AUser

B1

CAppDatabase

DUserDao

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up class names or using incorrect version numbers.

The entity is User, the version is 1, and the database class is named AppDatabase.