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Need help on the convincing the team not to use !! operator. Recently switched jobs and the code base is full of !!. Any article with a strong recommendation from Kotlin itself?

Nothing wrong with !! IMO I think both @elizarov and @Adam Powell have both mentioned on here a few times that !! is a great way to assert an invariant. If they are using !! to simply satisfy the compiler, then yes that's bad. But if they are using it to say "this should never be null" then its fine to use and more convenient than other methods. Of course there are exceptions, but most people don't like !! because they think it looks ugly or screms that something is wrong. Which I found myself doing in the early days of kotlin, but now I use !! everywhere. 😄 tagged both of those users above because I don't actually want to misconstrue their opinions, but I think in general they both think !! is fine

Hi guys. Just joined this slack channel. Passionate Android developer here. You may know me as the

coroutineDispatcher

by username, because I like scheduling stuff in my personal life and I use coroutines 😛 Usually I try to stay active in Stack Overflow, Reddit Androiddev, Kotlin channel. Also I love open source and try contributing if time. Proffesionally I have been working as an Android developer for 2 years and 11 months 🙈 and I love what I do. Currently based in Munich. See ya around 👋

is there any way to determine the type of a visible item in RecyclerView by asking the adapter?

Hi All! I have enable proguard in my project. The app is running great, no crashes and behave like it should. But I when I run the instrumentation tests suddenly I have a lot of weird error, mostly related to kotlin like:

java.lang.NoClassDefFoundError: Failed resolution of: Lkotlin/collections/CollectionsKt;

java.lang.NoClassDefFoundError: Failed resolution of: Lkotlin/ranges/RangesKt;

And I find myself adding a bunch of rules to my proguard files to make my tests pass when my app is working fine. Any idea what I am doing wrong? Am I missing something?

Anyone know why my project xml become like this?

What's the best architecture for handling events in a recyclerview adapter that need to make network calls? So each cell can be clicked on to launch other actions, which may include network calls. I would assume you would not make network calls directly from the adapter. But should the adapter hold a reference to the fragment's ViewModel, and thereby be able to make network calls directly via the view model, or should the adapter just pass the call to the fragment and the fragment calls the viewModel? So it would be adapter -> ViewModel -> network call, or adapter -> fragment -> ViewModel -> network call. The adapter NOT holding a reference to the ViewModel feels right to me, but I'm wondering what's best, or if it matters.

Hi all, I'm trying to wrap my head around how coroutine/flow works. I have the following in my viewmodel

private val _status = MutableLiveData<Status>()
val status: LiveData<Status>
    get = _status

fun getStatus(id: Int) {
    viewModelScope.launch {
        repository.getStatus(id)    // This return Flow<Status>
            .collect { _status = it}
    }
}

And I use data binding on my layout

<TextView
    android:text="@{viewModel.status}" />

The UI doesn't get updated to the latest value as the status come through from repository, the Main thread is being held up. If I switch the coroutine to use Dispatcher.IO, I got

"java.lang.IllegalStateException: Cannot invoke setValue on a background thread"

as the status need to be set on Main thread. I've tried using BroadcastChannel

private val statusChannel = BroadcastChannel<Status>(Channel.CONFLATED)
val status = statusChannel.asFlow().asLiveData()

fun getStatus(id: Int) {
    viewModelScope.launch(<http://Dispatcher.IO|Dispatcher.IO>) {
        repository.getStatus(id)    // This return Flow<Status>
            .collect { statusChannel.offer(it) }
    }
}

But the idea of converting the channel back to flow feels odd. What's the best way to approach this?

Do you use GlobalScope/NonCancelable for database operations in coroutines? If not, how do you avoid that the operation ends prematurely (for example by closing the app)

Anyone here using Jetpack DataStore? When my fragment starts I want to load a value once. Right now I'm doing it like this, but it looks a bit awkward. Is this the correct approach? (this is inside

onCreateOptionsMenu

)

Is there any chance I can fix the indexing without upgrading/downgrading this version of canary? What I tried is only invalidate+restart and the indexing is still broken 😕 Can't even import a class or something, the whole package name comes when I type 🙈 Android studio version: 4.2 Canary 12 Gradle plugin: 4.2.0-alpha12

Very often, after making a change to a

ViewModel

class, I get bizarre “error: cannot find symbol” compilation errors (in corresponding generated java class for ViewModel) where the only way forward is to do a clean build, and then everything compiles as expected. Is there some gradle setting I can tweak to avoid this?

Execution failed for task ':mymodule:kaptDebugKotlin'.
> A failure occurred while executing org.jetbrains.kotlin.gradle.internal.KaptExecution
   > java.lang.reflect.InvocationTargetException (no error message)

Is jetpack and jetpackCompose a different thing?

Hi everyone, I want to ask help from you guys to answer my question at Stack Overflow, it's about asymmetric encryption using RSA algorithm in Kotlin for Android env of course. I had searching the answer for days, but it's a dead end for me. Thank you all. Here's the link. https://stackoverflow.com/questions/64087039/incompatible-padding-mode-when-decyrpt-usiing-cipher-with-instance-rsa-ecb-pkcs

Hi everyone. Does Raywenderlich course worth to subscribe?

I have ViewModelFactory which requires me to pass class as a constructor. But currently the class is an interface. May I know how can I achieve this?

interface VoteRepository {
    fun getVoteDetails(): MutableLiveData<ArrayList<Vote>>
}

val voteViewModelFactory = VoteViewModelFactory(// I need to pass the VoteRepository here)

Hello everyone, My app often takes a long time to review ( 2 weeks or 1 month), even though it has over 1 million users, in-app-purchase and is regularly updated new features/hotfix every 2 weeks. Does anyone have a way for Google to prioritize reviewing apps? 😥

Hi guys. I have the following code below, why my chart result always render before

LiveData

?

private fun getVoteData(): ArrayList<PieEntry> {
    ...
    val viewModel = ViewModelProvider(this, voteViewModelFactory).get(VoteViewModel::class.java)
    val liveData = viewModel.getVote()
    liveData.observe(viewLifecycleOwner, { vote ->
        vote.forEach {
            votes.add(PieEntry(it.total.toFloat(), it.name))
        }
    })
    return votes
}

private fun generateChart(binding: FragmentPieChartBinding, getVoteData: ArrayList<PieEntry>) {
    ...

    // Run before livedata execute
    Log.d("TEST", votes.toString())

    ...
    // Render chart result
}

Am trying to commit data to a room database

AppExecutors.getInstance().diskIO().execute(new Runnable(){

    @Override
    public void run() {
        appDatabase.UIDao().insertUI(UI);
    }
});

but I’m getting an error`Attempt to invoke virtual method 'com.journaldev.firstandroidassignment.dao.UIDao com.journaldev.firstandroidassignment.database.AppDatabase.UIDao()' on a null object reference.` Any help would be much appreciated

Hi folks, I’m curious if there is any point to using thread annotations with Kotlin, assuming you are not managing any threads directly, and just using coroutines? My use case is: I have a third-party library which throws an exception if certain methods are not run on the main thread. I would like to annotate these methods in a thin wrapper so that Android Studio will generate a warning. But I don’t see how to do this; when I annotate the methods and launch from e.g. Dispatchers.IO, I don’t get a warning

-keepattributes *Annotation*, InnerClasses
-dontnote kotlinx.serialization.SerializationKt
-keep,includedescriptorclasses class com.yourcompany.yourpackage.**$$serializer { *; } # <-- change package name to your app's
-keepclassmembers class com.yourcompany.yourpackage.** { # <-- change package name to your app's
    *** Companion;
}
-keepclasseswithmembers class com.yourcompany.yourpackage.** { # <-- change package name to your app's
    kotlinx.serialization.KSerializer serializer(...);
}

The package name is changed,.. getting exception in kotlinx.serialization 1.0.0-RC

Serializer for class 'e' is not found.
    Mark the class as @Serializable or provide the serializer explicitly.

Data classes are in shared code. Why progaurd configuration is not working with minify enabled.  can anyone help what I am missing here? GitHub Kotlin/kotlinx.serialization Kotlin multiplatform / multi-format serialization - Kotlin/kotlinx.serialization

Hi Everyone, Just wanted to understand regarding the MIT license. If there's a open source lib under MIT license and i copy one of it's whole class file in my android application. Do i need to give credits to the original author in the class file header, considering the legality of it. I read online and yes it makes sense to add credit as one of the reason and other reasons like helping future dev to go the source code as ref and all. But, just considering the legality of it, if someone's fails to add the credit - does that mean the MIT license is violated?

Anyone has useful shortcuts for android studio? I’ve been adding Kotlin methods with command + enter on mac and found it very useful. Are there any other shortcuts I should know?

@Ian Lake @matvei @Ryan Mentley @tcracknell @jim @Adam Powell @Alexandre Elias [G] @msfjarvis Here's an interesting bug/race I've found in the kotlin coroutine port to Android/Jetpack. Let's assume we're operating inside of a fragment, using the fragment's lifecycle coroutine scope. Consider code like this:

lifecycleScope.launch {
	try {
		// do stuff
		delay(5000)
		// do stuff
	} catch (_: Throwable) {
		requireContext()
	}
}

When the Fragment is destroyed (by, e.g., the user pressing the back button), the Fragment's coroutine scope will be properly cancelled, as you'd expect. This in turn raises a CancellationException inside the scope. This exception is caught by our catch block, above. requireContext() is then called, and throws a new exception, because the context has already been destroyed. It seems like destruction of the context and such is happening in the wrong order. What should be happening instead is that context and binding and other various members that Fragment has should be set to null only after coroutines have exited. The example is contrived, but imagine something a bit more sophisticated, like:

lifecycleScope.launch {
	try {
		binding!!.config = getConfigAsync()
	} catch (_: Throwable) {
		binding!!.config = null
	}
}

Or, even more innocent looking:

lifecycleScope.launch {
	try {
		// do something expensive
	} catch (_: Throwable) {
		Toast.make(ctx, getString(R.string.error_string), LONG).show()
	}
}

That getString will crash too. You might respond that CancellationException should always be handled differently in every try-catch block ever for all coroutines. Maybe you're right. But that's a lot of refactoring and weirdness. And it seems like this would be better solved by just fixing the race of lifecycle shutdown vs context detachment. Does that seem reasonable?

#ask anyone know how to custom this callendar?

Hi all, got a question on Kotlin/Coroutine, does viewModelScope cancel all child coroutine onCleared()? Here's my view model (use in Profile Fragment)

class profileViewModel: ViewModel() {
    val profileRepository: ProfileRepository
    fun subscribeToProfile(id: Int) {
        viewModelScope.launch {
            profileRepository.subscribeToProfile(id)
        }
    }
}

My repository class

class ProfileRepository {
    fun subscribeToProfile(id: Int) {
        withContext(<http://Dispatchers.IO|Dispatchers.IO>) {
            .....       // Does this get cancelled onCleared()?
        }
    }
}

It seems to me the function in repository class still running despite I've navigated away from Profile Fragment. I've tried to debug on the view model and override the onCleared() function and call

.cancel()

override fun onCleared() {
    super.onCleared()
    viewModelScope.cancel()
}

I was able to breakpoint in

onCleared()

and execute the

.cancel()

but it doesn't cancel the job in repository. Am I missing any steps here?

This message was deleted.

Hello, how to manage variable datatype var aa=0 and var aa=0.0 ? with out A*ny* key used?