kotlinlang #android

I'm new to kotlin, and created a sample Multiplatform application(common code will be shared between Android and IOS) using https://kotlinlang.org/docs/tutorials/native/mpp-ios-android.html#creating-an-android-project reference. Everything is working fine except

bin

folder is not getting generated in `SharedCode/build`folder i rebuild the project, and was getting jar for andorid but not getting

SharedCode/build/bin/iOS/main/debug/framework/SharedCode.framewor

only these folders are getting generated, see attached image.

Alex Davidyuk

08/07/2019, 4:43 PM

I have a ImageButton with a drawable shape as the background. The shape has a solid android:color="someColor". I'm wondering how I could animate the color with a breathing/puslating effect so that it beckons the user to tap on the button? Anybody have ideas? I've look around on multiple stack overflow approaches, but they're quite dated and I couldn't translate the Java code presented to the proper Kotlin. Any help would be appreaciated!

08/07/2019, 5:17 PM

it gets removed by kotlinc/javac because it's a compile-time constant

👍 4

Paul Dhaliwal

08/07/2019, 8:13 PM

In a lot of cases on android calls like this come up

ContextCompat.getColor(context, color.colorPrimaryDark)

which gives the error “type mismatch Required Context, Found Context?” I can get around this error by using “context as Context” or “context!!“, however these don’t feel like the right approaches. The Kotlin doc says !! is for “NPE-lovers” which I am not lol. What’s the best way to handle these situations? I’m still new to Kotlin and development in general and don’t want to develop any bad habits. Thanks!

scottiedog45

08/08/2019, 1:20 AM

how does a ViewModel provider (something like

Copy code

singleLargeTextInputViewModel = ViewModelProviders.of(this, SingleLargeInputViewModel.FACTORY(NetworkService())).get(
            SingleLargeInputViewModel::class.java
        )

) “know” (????) that a view model already exists? Or would it?

myanmarking

08/08/2019, 9:07 AM

i guess this will work:

Copy code

ZoneId.of(timeZone.id)

☝️ 1

Branimir Conjar

08/08/2019, 3:29 PM

I have the following code:

Copy code

arguments?.getString(FORCED_EMAIL).let {
      binding.etEmail.setText(it)
      binding.etEmail.isFocusable = false
      binding.etEmail.isEnabled = false
    }

getString()

returns null. Anyone has an idea why this goes through and executes statements inside let?

TheDukerChip

08/09/2019, 4:31 AM

Does anyone know where to file a bug for

androidx.biometric

jermainedilao

08/09/2019, 10:01 AM

Hi guys! I have a question regarding MVVM. Let’s say I have a ViewPager that has 3 pages and has automatic scrolling feature. (this viewpager goes back to page 1 when reaching page 3). The auto scrolling feature is PAUSED everytime the viewpager receives a touch action. Now, should the logic of setting view pager’s current item to 1 if it reaches 3, and the pausing of auto scroll when view pager receives touch event RESIDE in ViewModel? In my understanding. Purely UI logic can stay in activity/fragment. Logic that can reside in ViewModel can include enabling/disabling buttons (depending on the input), validating inputs, etc. Any inputs are greatly appreciated!

Gunslingor

08/11/2019, 3:25 PM

Any idea's why this font isn't wrapping correctly?

henrikhorbovyi

08/12/2019, 4:06 PM

Hey guys... Is it a bad practice to leave

logs

on the code (with the purpose of future debug)?

Simon Schubert

08/12/2019, 4:14 PM

Usually one of the first things I create in a new android project is a L class. Which makes logging easier and also prevents logs to go into a non-debug versions

Copy code

object L {

    private const val TAG = "FOOBAR"

    fun e(log: String) {
        if (BuildConfig.DEBUG) {
            Log.e(TAG, log)
        }
    }
    ...
}

Marc Knaup

08/12/2019, 9:15 PM

So, for coroutines there’s that nice

val myData = liveData { … }

extension. How can I achieve the same with

MutableLiveData

? There is no

mutableLiveData { … }

. 1. Load document from DB using a coroutine upon activation (

onActive

). 2. Update view model when Fragment requests changes & save them to DB (also using a coroutine).

ivano

08/13/2019, 12:04 PM

Copy code

@Parcelize
class RemoteDeclarationRepository : DeclarationRepositoryInterface {

    private val declareService: ProActiveDeclareApi
        get() = Api()

    override fun getDeclarations(periodId: Int, offset: Int, limit: Int): Single<DeclarationsResponse> {
        return declareService.getDeclarations(periodId, offset, limit)
    }

    override fun getDeclarationPeriod(id: Int): Single<DeclarationPeriod> {
        return declareService.getPeriod(id).map { it.data }
    }       //and so on 50 times almost

Marc Knaup

08/13/2019, 12:15 PM

Question regarding coroutines vs. Android lifecycle: Saving to & loading data from a database should not happen on the main thread, hence using coroutines are great for that. Now let’s say I have an activity and save data in

onPause

onStop

, e.g. in case the user switches to another application. The launched coroutine’s scope however cannot be bound to the activity’s lifecycle because the save operation may not have finished by the time the activity gets destroyed. Even worse the whole app may be destroyed or hibernated because there are no activities left, which would abort the save operation. How would I model that properly? • The most simple solution I can think of is to block the main thread on

onStop

and wait for the coroutine to complete. But that’s somewhat counter-productive 🤔 OTOH that would ensure that if the user switches to another activity they’d not risk seeing stale data because the save hasn’t completed yet. • Another solution could be a long-running service for any kind of database I/O but that seems unnecessarily complex (and may even need a foreground service?).

Pablichjenkov

08/13/2019, 8:14 PM

Is out there any Retrofit CallAdapter that returns

Flow<T>

. Is it a bad design?

arekolek

08/14/2019, 6:29 AM

Anybody usining

@Parcelize

got rid of this lint error?

alex.tavella

08/14/2019, 5:12 PM

Do you guys think

@VisibleForTesting

a bad practice for unit testing internals of a component?

Mohamed Hamdan

08/14/2019, 8:31 PM

Hi all, A while ago there was someone asking about eventbus libraries and all answers were about not using any kind of eventbus libraries, I want to know what should we use instead of eventbus libraries.

raghuramjampala

08/15/2019, 2:25 PM

Hi all, I have created an internal view which should only be used in the module where it is created, but I can see it in xml in the other module which has the dependency (It is hidden from kotlin but visible from XML). How Do I make it hidden from the other module’s xml as well?

jmfayard

08/15/2019, 4:13 PM

Would someone be nice enough to proof-read this article?

Better dependency management in Android Studio 3.5 with Gradle buildSrcVersions

https://dev.to/jmfayard/new-in-android-studio-3-5-dependency-management-with-gradle-buildsrcversions-22ia-temp-slug-2042205?preview=373ea29273e40c80e4579a999bbc305e8246511e13d599564be52fba5f20607b13305942fd8c4855b5e1807a66249612df27e19193a563106eb8d275 I will publish once Android Studio 3.5 is released (should be real soon now)

리오

08/15/2019, 8:39 PM

Can fragments itself host bottom navigation? I got it to work on activity class but I can't seem to implement it inside the fragments. The reason for wanting to add the bottom navigation to the fragment is because I want to build a single activity application. I actually created a stackoverflow question, and the post has more information about the code https://stackoverflow.com/questions/57514369/how-to-add-bottom-navigation-listeners-to-fragments. Any input suggestion is welcome 😊 thx.

Yuri

08/15/2019, 11:10 PM

Hey guys, I’m trying to migrate RxJava code dealing with SharedPreferences to Kotlin Flow. How correct migration should look like?

Copy code

private val keyChangesObservable: Observable<String>

  init {
    keyChangesObservable = io.reactivex.Observable.create(ObservableOnSubscribe<String> { emitter ->
      val listener = SharedPreferences.OnSharedPreferenceChangeListener { _, key -> emitter.onNext(key) }
      emitter.setCancellable { prefs.unregisterOnSharedPreferenceChangeListener(listener) }
      prefs.registerOnSharedPreferenceChangeListener(listener)
    }).share()
  }

Paul Dhaliwal

08/16/2019, 12:06 AM

I've created a line chart by making a custom view. I want to be able to animate the line in the chart and the axis lines and value labels seperately. Does this require creating a custom viewgroup which contains custom views for the plotted line, axis lines, and value labels seperately? Or is it better to do this all in one custom view? As an example of how I'd like to be able to control animations I'm looking at the Google Fit App, which has custom animations for the different elements in its graphs. Thanks!!

Kulwinder Singh

08/16/2019, 6:08 AM

Hi, What is best way to detect "No Internet connection" using Retrofit + Coroutines, currently i have added interceptor

Copy code

private val realInterceptor = Interceptor { chain ->
        if (!NetworkConnection.getInstance().isConnected) {
            throw NoInternetException()
        }
	/..../
    }

but to work with this i have to add

try/catch

block on every request, there are so many requests. Below is sample of how i'm handling each network request->

Copy code

val response = apiService.getItems().toNetworkResult()
        when (response) {
            is NetworkResult.Success -> onDataLoaded(response.data)
            is NetworkResult.Error -> toast(response.errorCode)
        }

and this is how

toNetworkResult

looks like

Copy code

fun <T : Any> Response<T>.toNetworkResult(): NetworkResult<T> {
    val response = this
    if (response.isSuccessful)
        return NetworkResult.Success(response.body()!!)

    val error = GsonUtils.toObject<ErrorResponse>(response.errorBody()!!.string())
    return NetworkResult.Error(response.code(), error)
}

I just want to know if it is possible to handle it inside
toNetworkResult()
or any other similar solution i can implement, where i don't have to add
try/catch
on every request

Zaraki596

08/16/2019, 12:33 PM

https://stackoverflow.com/questions/57458511/how-do-i-achieve-on-scroll-behavior-where-both-the-toolbar-and-bottom-navigation