MVVM with Flows in Kotlin

ChandraSaiMohan bhupathi
2 min readJul 5, 2021


This story describes creating a simple Android application that uses MVVM architecture along with Flows .

Basics of Flow:

What is Flow ?

  • A flow is a stream of values that are asynchronously computed.
  • Flows emits values and there is other process/coroutines that receives/process the emitted values.

Creating Flows

Ways to Create Flow:

(1) Generate values by emitting each value

fun emitNumbers(): Flow<Int> = flow{
val numList = listOf<Int>(1,2,3,4,5,6,7)
numList.forEach {

(2)A collection can be directly converted into a flow.

fun convertingCollectionInToFlow() = listOf<Int>(1,2,3,4,5,6,7,8,9,10).asFlow()

(3)A flow can be generated from a number of parameters of any type.

fun creatingFlowWithNumberOfParameters()= flowOf("one","two","three")

Using Flows in Android with MVVM Architecture:

The example explained in this story is a very basic example.

What this example does?

This example fetch list of data from network and displays in the list.



Created a data class that represents the model of the API response

class PostsModel : ArrayList<PostsModel.PostsModelItem>(){
data class PostsModelItem(
val body: String, // cupiditate quo est a modi nesciunt soluta ipsa voluptas error itaque dicta in autem qui minus magnam et distinctio eum accusamus ratione error aut
val id: Int, // 100
val title: String, // at nam consequatur ea labore ea harum
val userId: Int // 10

API service Interface:

This interface contains the retrofit methods to fetch data from network

interface PostsService {
suspend fun fetchPosts(): List<PostsModel.PostsModelItem>

Repository :

We need a repository to communicate with PostsService to fetch data.

This is the place where we use flow .

fun getPosts(): Flow<PostsModel.PostsModelItem>{
return flow {
val postList = postsService.fetchPosts()
println("PostsList is $postList")
postList.forEach {


The getPosts() method returns flow of model item.

This method calls a method from postsService and emit each item in the list to the viewModel with some delay.


View model will have one method that returns live data. A flow can be converted to live data using method .asLiveData()

class ListViewModel: ViewModel() {

val posts = PostRepository().getPosts().asLiveData()


The received live data from view model will be observed in view as below:


private fun observeViewModel() {
viewModel.posts.observe(this, Observer { post ->
loading_view.visibility = View.GONE
newsList.visibility = View.VISIBLE

Each item emitted from flow will be added to the top of the list and position is scrolled to the added position as above.

Github link for Code: