Repository

Question 1

Which 3 “concerns” ought to remain separated in different components?

Answer 1

A change to any one of these should not necessitate any changes in the others

Network - where the data is fetched from and how
Domain - data classes representing the app’s data
Database - schema’s structure

Question 2

What are the 4 methods of caching in Android

Answer 2

Retrofit - can be configured to store a copy of every network result locally

SharedPreferences - can store a small number of k-v pairs

App’s internal storage - App’s package name specifies internal storage directory. Private to your app and cleared when app is deleted.

Room - a SQlite object-mapping library

Question 3

Give syntax for a good way of converting a list of object of one type to a list of objects of a similar type

Answer 3

fun List^MyObject^.asListOfSimilarObjects( ): List^MySimilarObject^ {
  return map{
    MySimilarObject(
    val1 = it.val1
    ...
  }
}

Question 4

1. What is a repository?
2. Give 3 examples of data sources.
3. What is the repository pattern?

Answer 4

1. Repository: mediates between data sources.
2. Data sources:
   persistent models, web services, caches
3. Repository pattern: isolate data sources from the rest of the app. Provide an API for the rest of the app to access various data sources.