Repository pattern in depth in Android Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a repository interface in Kotlin.

Android Kotlin

interface UserRepository {
    fun getUserById(id: Int): [1]
}

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

AInt

BString

CUser

DBoolean

Attempts:

3 left

💡 Hint

Common Mistakes

Returning a primitive type like Int or String instead of a User object.

Forgetting to specify the return type.

The repository interface defines a method that returns a User object by its ID.

2fill in blank

medium

Complete the code to implement the repository class that fetches data from a local data source.

Android Kotlin

class UserRepositoryImpl(private val localDataSource: LocalDataSource) : UserRepository {
    override fun getUserById(id: Int): User {
        return [1].getUser(id)
    }
}

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

AremoteDataSource

BuserService

CuserDao

DlocalDataSource

Attempts:

3 left

💡 Hint

Common Mistakes

Using remoteDataSource instead of localDataSource.

Using undefined variables like userDao or userService.

The repository implementation uses the localDataSource to get the user data.

3fill in blank

hard

Fix the error in the repository method to return a nullable User when not found.

Android Kotlin

override fun getUserById(id: Int): [1] {
    return localDataSource.getUser(id)
}

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

ABoolean

BUser?

CList<User>

DUser

Attempts:

3 left

💡 Hint

Common Mistakes

Returning a non-nullable User type which causes errors if user is missing.

Returning a list or Boolean which does not match the method purpose.

The method should return User? to indicate the user might not be found (nullable).

4fill in blank

hard

Fill both blanks to create a repository method that saves a user and returns success status.

Android Kotlin

fun saveUser(user: User): [1] {
    val result = localDataSource.[2](user)
    return result > 0
}

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

ABoolean

BInt

CsaveUser

DinsertUser

Attempts:

3 left

💡 Hint

Common Mistakes

Returning Int instead of Boolean.

Calling a method named saveUser which does not exist in data source.

The method returns a Boolean indicating success. It calls insertUser on the local data source.

5fill in blank

hard

Fill all three blanks to define a repository method that fetches users filtered by age greater than a value.

Android Kotlin

fun getUsersOlderThan(age: Int): List<User> {
    return localDataSource.getUsers().filter { user -> user.[1] [2] [3] }
}

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

Aage

B>

Dname

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong property like name instead of age.

Using wrong comparison operators.

The filter checks if the user's age is greater than the given age parameter.