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Good morning guys, I wanna ask you about an efficient way of app’s structure, when I create an app I often use only one activity, then in that activity I include a container fragment and put all other fragments into that container fragment. So is that an efficient way of app’s organization?

Just out of curiosity. I have been watching a practice that is becoming popular about using backing properties to shortcut Kotlin nullability check. (For example)

private var _binding: ViewBinding? = null
private val binding get() = _binding!!

And I was wondering why this is better than just a

lateinit property

(which, in my humble opinion, is more concise)

private lateinit var binding: ViewBinding

Or even if

_binding

is going to be mutated to null, it would be better to use the language constructors to check the possibility. Am I missing something?

after upgrading to android studio 4.1 , i am getting this warning for using switch cases in one particular java code:

Resource IDs will be non-final in Android Gradle Plugin version 5.0, avoid using them in switch case statements

. i found this article related to this issue : http://tools.android.com/tips/non-constant-fields . i usually use kotlin, but maintain some java projects. as a kotlin user, is it still okay to use

when-else

blocks with resource ids? or would that be impacted too ?

Being a kotlin slack, it makes sense that we want all questions to be kotlin related, but I think so many people have found help in this community that it's become "trustworthy" (way more so than that androidunited slack) and because of that it makes sense why people post non-kotlin android questions here. I wish there was an "official" android slack. android-dev irc was fun when there were framework people hanging out. Maybe to "fight" this for now we rename the channel android-kotlin or something?

Language makes software, software is language. Kotlin is now the language of Android. Android is now becoming Kotlin, they are related by definition. There is no need to have, or start, another software war. Why can we not just ask the questions we need answered in the place that is most likely to answer them? GRASP Has the Information Expert principle:

Assign responsibility to the class that has the information needed to fulfill it.

This slack community has all the information experts. So it is natural for people to assign theirs questions to here. Fighting this behaviour is probably futile and also alienating to its members.

Hello guys, When I use Gson with Kotlin, I experience inconvenience because of unstable nullable parsing, polymorphic deserialize and many things.. So I want use another Json parser, can anyone recommend Json parser library? The specific environment is Retrofit + Gson for http request and I will migration Gson to new json parser. I think moshi is optimal choice, because I know kotlinx.serialization is unstable and still experimental for build retrofit converter. I think I'd be grateful if anyone gave me an opinion 🙇

I know this is not Kotlin question, but does anybody have good experience with Constraint Layout. I can't figure out what constraints to set for a specific scenario

Hello, when I pass to a fragment from another fragment, the previous fragment is visible. What is the reason?  The height of all fragments are match_parent.

val compFragment = CompFragment()
 compFragment.arguments = bundle
 requireFragmentManager().beginTransaction().replace(R.id.comp_item, compFragment)
     .commit()

🙋 Roll call! Who else is here?

Hello everybody, when I pass to a fragment from another fragment, the previous fragment is visible. What is the reason?  The height of all fragments are match_parent and background colors are different.

val compFragment = CompFragment()
 compFragment.arguments = bundle
 requireFragmentManager().beginTransaction().replace(R.id.comp_item, compFragment)
     .commit()

☝️ Added the r/androiddev Discord server to the list of relevant communities. It has 11k members and is the ideal place for general Android questions. Edit: Sorry about the spam - Slack did not indicate that it would ellipsize the description (didn't display the limit warning) 🙂

hello anyone here using registerForActivityResult() in a fragement while overriding onActivityResult in the host activity. My callback never gets called

Which one is better to use in android projects?

Parcelable

or

Serializable

?

Hi I am using net.sqlcipher to encrypt my app database, we are getting device specific crashes logged in firebase in field, logs are pasted below, suggestions will be appreciated Fatal Exception: java.lang.IllegalStateException database not open  (SQLiteDatabase.java:109)  (AndroidSqliteDriver.java:6)  (Transacter.java:6)  (TransacterImpl.java:25)  (TransacterImpl.java:5)  (TransactionExternsionsKt.java:16) Fatal Exception: java.lang.UnsatisfiedLinkError: dalvik.system.PathClassLoader[DexPathList[[zip file “/data/app/com.philips.phsleep-reJnoXvYSDyN5sVbGFw0mQ==/base.apk”],nativeLibraryDirectories=[/data/app/com.philips.phsleep-reJnoXvYSDyN5sVbGFw0mQ==/lib/x86, /system/lib, /vendor/lib]]] couldn’t find “libsqlcipher.so” at java.lang.Runtime.loadLibrary0(Runtime.java:1011) at java.lang.System.loadLibrary(System.java:1657) at net.sqlcipher.database.SQLiteDatabase$1.loadLibraries(SQLiteDatabase.java:6) at net.sqlcipher.database.SQLiteDatabase.loadLibs(SQLiteDatabase.java:9) at net.sqlcipher.database.SQLiteDatabase.loadLibs(SQLiteDatabase.java:8) at net.sqlcipher.database.SQLiteDatabase.loadLibs(SQLiteDatabase.java:7) at net.sqlcipher.database.SupportHelper.<init>(SupportHelper.java:5) at net.sqlcipher.database.SupportFactory.create(SupportFactory.java:8) at com.squareup.sqldelight.android.AndroidSqliteDriver.<init>(AndroidSqliteDriver.java:2) at com.squareup.sqldelight.android.AndroidSqliteDriver.<init>(AndroidSqliteDriver.java:55) at com.hp.sleep.shared.datasource.DataSourceProvider.open(DataSourceProvider.java:76) at com.philips.phsleep.SleepApplication.openDB(SleepApplication.java:9)

So I tried setting an error while validating a text field and the error shows up at the end of the view below the icon, like this. How do I make sure that the error is the the form of a text only, and is right below the text input field?

Hi! I had a question. Why setMaxDate is not available in Kotlin's DatePickerDialog? I am attaching the picture of code. You see, the IDE doesn't seem to suggest me setMaxDate and insetead suggests about maxDate which is another function

[Flow + LiveData]

Hi, we have been adopting

Flow

on our app and there are still some behaviors that we want to achieve that are a bit unclear. So, our presentation architecture basically consists on archictecture component’s

ViewModel

producing state in a

ViewState

class that has its properties exposed as

LiveData

, which are observed by the

View

layer. We have a case similar to the following:

internal class HomeViewModel constructor(
    observeSessionAddress: GetSessionAddressFlowUseCase,
    getHome: GetHomeUseCase,
) : ViewModel {
    private val addressStream = observeSessionAddress()
        .distinctUntilChanged()
        .shareIn(viewModelScope, SharingStarted.Lazily, replay = 1)

    private val homeStream = addressStream
        .map { getHome(it.lat, it.lon) }
        .shareIn(viewModelScope, SharingStarted.Lazily, replay = 1)

    val viewState = HomeViewState(
        addressStream.asLiveData(),
        homeStream.asLiveData()
    )
}

internal class HomeFragment : Fragment() {
...
    override fun onViewCreated(
        view: View,
        savedInstanceState: Bundle?,
    ) {
        super.onViewCreated(view, savedInstanceState)
        ...
        with (viewModel.viewState) {
            address.observe(viewLifecycleOwner, ::updateAddress)
            home.observe(viewLifecycleOwner, ::updateHome)
        }
    }
}

The class

GetSessionAddressFlowUseCase

returns a

Flow

. The code works fine, when Fragment is firstly created, it starts observing the address and fetches home content appropriately and also when navigating forward and getting back, we get the previous value without actually triggering

getHome

again. The only problem is: by using

shareIn

I just made

homeStream

and

addressStream

hot flows, and after leaving

HomeFragment

by navigating forward (we replace this fragment and keep in the backstack, so only

onDestroyView

is called), the hot flow will still be live since

HomeViewModel

is still alive and hence if we change address on another screen, the

getHome

use case will still trigger. That may seem harmless at first, but if other devs start following this approach, we might trigger a bunch of expensive operations even if that info is not important to the user at that moment. One alternative is to keep these streams as cold, but after navigating back to the

Fragment

would trigger

getHome

again, which is an expensive operation, so that is out of the question. Any ideas/suggestions?

does anybody know how https://pastebin.com/5JYdjBeE differs from https://pastebin.com/jr3DxT5a ?

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In Fragment collecting a UI state Flow, which one of the following scopes you use to collect UI state? 1️⃣`lifecycleScope` 2️⃣`viewLifecycleOwner.lifecycleScope`

In a Fragment collecting a UI state Flow, which one of the scope methods do you use? 1️⃣`launch {}` 2️⃣`launchWhenCreated {}` 3️⃣`launchWhenStarted {}` 4️⃣`launchWhenResumed {}`

Hello, everyone ! 👋 Quick question: when I create a Kotlin only module in an Android Project (

apply plugin: 'kotlin'

), do I have to setup anything for ProGuard/R8? In other all modules, there is

minifyEnabled

set to

true

, but this setup is inside

android

tag. Thanks a lot in advance! ❤️

hello everyone i saw this code and i didnt understand how this guy make this it passes the actions and show the view, is it a class with higher order functions or what ? is there a tutorial to learn this kind of code thanks

alert("We can't show your position because you generally disabled the location service for your device.") {
        yesButton {
        }
        neutralPressed("Settings") {
            startActivity(Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS))
        }
    }.show()

Quick question : Do my view IDs (in integer) change after every clean install of the app? Example : I've given an id to the card view via XML (let's say it's called safeCard) Now this view has an integer ID to it. I'm saving this on my database and retrieving it for a user. So when I reinstall my app, does safeCard's id change?

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Any nice way of handling this use case with the Kotlin

with

keyword?

with(myFragmentBinding){
   viewId.text = stateDataClass.name
   viewId2.text = stateDataClass.lastName
   viewId3.text = stateDataClass.phoneNumber
}

And I was thinking if there is any nice way of also not repeating the right part. Something like

with(Pair(binding, modelClass))

doesn’t look pretty nice to me as it might look a little bit ugly and not intuitive (

first.viewId.text = second.name

) which I don’t like. A nested with is also ugly IMO. Any opinions, thoughts?

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I'm new in Kotlin Flow. I'd like use with Retrofit but i don't understand if and when can i use Flow in Retrofit interface. I 'm using slack eithernet to get network response :

@GET("v2//news")
suspend fun news() : ApiResult<List<News>, ErrorResponse>

In this way i can't use

Flow<ApiResult<List<News>, ErrorResponse>>

so can i use in repo?

fun getNews(): Flow<List<News>> {

return flow {

}

}