Android Example App

Introduction

I decided to base my application on the CLEAN architecture and set about looking for great examples.
I found Lopez at https://github.com/lopspower/CleanRxArchitecture which had all of the features I looking for

• Retrofit2
• Room
• RxJava

Implementing Screens

The Model

The model for the screens has data associated with each type of data to be displayed. With each construction pass the state and either the content type of data.

class CovidResultListViewModel(
    val loadingState: LoadingState = LoadingState.NONE,
    val contentState: ContentState = ContentState.NONE,
    val covidResults: List<CovidResult>? = null,
    var errorMessage: String? = null,
    val snackMessage: String? = null) {
...
    companion object {

        fun createData(data: List<CovidResult>?) =
            CovidResultListViewModel(contentState = ContentState.CONTENT, covidResults = data)

        fun createLoading() =
            CovidResultListViewModel(loadingState = LoadingState.LOADING, contentState = ContentState.CONTENT)

        fun createError(error: String) =
            CovidResultListViewModel(contentState = ContentState.ERROR, errorMessage = error)

...

    }
}

The Presenter has a render method which is responsible for rendering the data.

Refreshing

Android provides the SwipeRefreshLayout which is demonstrated below

Quite liked the approach of on by default. To implement this we

• Wrap the RecyclerView in it

        <androidx.swiperefreshlayout.widget.SwipeRefreshLayout
            android:id="@+id/swipeRefreshLayout"
            android:layout_width="match_parent"
            android:layout_height="match_parent">

            <androidx.recyclerview.widget.RecyclerView
                android:id="@+id/covid_result_recycler_view"
                android:layout_width="match_parent"
...
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toTopOf="parent" />

        </androidx.swiperefreshlayout.widget.SwipeRefreshLayout>