PatilShreyas

fun getAllPosts() = flow<State<List<Post>>> {

    // Emit loading state
    emit(State.loading())

    val snapshot = mPostsCollection.get().await()
    val posts = snapshot.toObjects(Post::class.java)

    // Emit success state with data
    emit(State.success(posts))

PatilShreyas

private suspend fun addPost(post: Post) {
    viewModel.addPost(post).collect { state ->
        when (state) {
            is State.Loading -> {
                showToast("Loading")
                binding.buttonAdd.isEnabled = false
            }

            is State.Success -> {
                showToast("Posted")

PatilShreyas

private suspend fun loadPosts() {
    viewModel.getAllPosts().collect { state ->
        when (state) {
            is State.Loading -> {
                showToast("Loading")
            }

            is State.Success -> {
                val postText = state.data.joinToString("\n") {
                    "${it.postContent} ~ ${it.postAuthor}"

PatilShreyas

class MainViewModel(private val repository: PostsRepository) : ViewModel() {

    fun getAllPosts() = repository.getAllPosts()

    fun addPost(post: Post) = repository.addPost(post)
}

PatilShreyas

fun addPost(post: Post) = flow<State<DocumentReference>> {

    // Emit loading state
    emit(State.loading())

    val postRef = mPostsCollection.add(post).await()

    // Emit success state with post reference
    emit(State.success(postRef))

PatilShreyas

sealed class State<T> {
    class Loading<T> : State<T>()
    data class Success<T>(val data: T) : State<T>()
    data class Failed<T>(val message: String) : State<T>()

    companion object {
        fun <T> loading() = Loading<T>()
        fun <T> success(data: T) = Success(data)
        fun <T> failed(message: String) = Failed<T>(message)
    }

PatilShreyas

data class Post(
    val postContent: String? = null,
    val postAuthor: String? = null
)

PatilShreyas

dependencies {

    // Kotlin
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"

    // Kotlin Coroutines
    implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core:1.3.5"
    implementation "org.jetbrains.kotlinx:kotlinx-coroutines-android:1.3.5"
    implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-play-services:1.3.5'

PatilShreyas

public class Main {
    public static void main(String[] args) {
        Life life = DaggerLifeComponent.create().getLife();
        life.enjoy();
    }
}

PatilShreyas

@Singleton
@Component
public interface LifeComponent {
    Life getLife();
}