What to filter a data class in Kotlin multiple times I want to write functions that perform filters on a list of my data class/object. I can filter the classes but it seem like I need to create a new list every time a want to filter again, is there any way around this? I create multiple functions and extension function but it does not work My data class and custom list data class Product( var name: String, var category: Category, var price: Double, var rating: Double ) object ProductList { var productList = listOf(...

How to efficiently extract album art from any music file using Kotlin Coroutines In my app i'm trying to extract album arts from all music files in phone storage and then i populate them into my recyclerview here i'm successfully getting everything but still it's taking a lot of time for all tracks to get rendered into my recycler view all i want to do is as soon my app is launced all tracks should be filled up in recycler view instantly with appropriate album art without any delay it tried put my code into coroutines but still it taking a lot of delay any help will be...

Unable to invoke no-args constructor for interface retrofit2.http.Url. Register an InstanceCreator with Gson for this type may fix this problem i have problem with retrofit and Gson and i don't know why? my app have an error when send data for login: Unable to invoke no-args constructor for interface retrofit2.http.Url. Register an InstanceCreator with Gson for this type may fix this problem. before i make this app with java and have exactly same code and doesn't have any error but now with Kotlin?? main activity: class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) {...

Understanding a parameter that is initialized as an extension function In the following code the parameter type for modelInitializer is CalendarMonthTitleModelBuilder.() What does the .() mean? I believe the dot refers to an extension. And when you add () after it, I think it means to create an instance of this type. Does this mean some anonymous extension is being created here and initialized? inline fun EpoxyController.calendarMonthTitle(modelInitializer: CalendarMonthTitleModelBuilder.() -> Unit) { CalendarMonthTitleModel_().apply {...

When is "onDetach" called in the new navigation component? I am using the new navigation component to navigate over my fragments. I noticed that onDetach method is called with some strange behaviour, which is causing me some problems, because I am using a custom TextWatcher for one of my views. In my current scenario onDetach is called after the onViewCreated on my next fragment, and for some reason the TextWatcher is not working anymore. I can provide more info if needed

Having trouble getting position on the 2nd Array I'm Using GSON to parse my JSON. I have an object that has 2 array object. I'm having a problem on getting the TransactionDetails position. I have a recyclerView that populates the "Transactions" and then when I tap on that it should open the "TransactionDetails". But I'm having trouble on getting the position on TransactionDetails what array to read. As you can see on the code I need to put a position on [0] because it only loads the 1st array on transaction details. JSON: <a...

Live Customer Support in android i am developing an android application in kotlin and i need to add live customer support in my application.Is there any way to add free live chat in chatbot or any other strategy to add customer-support in my application?

Kotlin polymorphic serialization (string array and object array) I have a server response that could return either an array of strings, or an array of objects, but I don't know how to define this polymorphic relationship. Here's the Kotlin code for the serializers. The sentence class needs to be a plain array, but the serializer needs a val key. @Serializable data class QuizResponse( val name: String, val quiz: List ) @Serializable data class Quiz( val id: Int, val question: String, val quiz_type: String, val video: BasicVideo,...

'No executable code found at line *' within lambdas in Android Studio 3.5 Whenever i try to debug lambdas within suspend functions i always get the "No executable code fount at line *". Sometimes this also occures within lambdas in regular functions. Regular and suspend functions debugging works fine. Lambdas not: Following some other answers i have already tried the following: removing .gradle, app/build and...

How to save a score in Kotlin? How can I save a score in my game scene even if I close the app and open it again? I'm new to android and I only know that in Swift things like that can be saved by using user defaults but I don't what to do in Android Studio. Here is the score I want to save: var score = 1 later in the scene -> override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) score =+ 2 //save the score here }

Kotlin's copy in data class does shallow copy? So I have the following data class: data class Client(val name: String, val pastAddresses: ArrayList) From the following code: val aClient = Client("Alice", arrayListOf("foo", "bar")) println(aClient) val cClient = aClient.copy() cClient.pastAddresses.add("Blah") cClient.pastAddresses.remove("foo") println(aClient) I see: Client(name=Alice, pastAddresses=[foo, bar]) Client(name=Alice, pastAddresses=[bar, Blah]) Which means that the copy in Kotlin's data class is a shallow...

What is the better way to transform one object to another in Kotlin? I've multiple object classes in my project and I need to transform one object to another. I tried creating a common util and start converting them the code started growing and was not able to manage in a single file. Then I started creating individual transformer class something similar to this, /** This transforms [Square] to [Rectangle] **/ object SquareToRectangleTransformer { fun transform(square: Square): Rectangle { checkNotNull(square.side) { missing ("side") } val...

In Kotlin language i need to create a photo app with custom image capture buttons and some design over the image like a frame. Any examples of this? I read that it uses surfaceView or something but I didn't find any good examples in Kotlin. Does anyone have a tutorial or template application for this?

Struggling converting java RxBle Code to Kotlin Im currently developing an android app with Kotlin. Its my first experience with this programming language and im currently struggeling to translate an example of Java code to Kotlin. I want to implement the answer to this question in Kotlin. my current implementation fails to compile because the Ovservable::from method seems to be removed. This is my...

Naviagate from a fragmentDialog to another fragment and back to dialog I want to go to another fragment from a dialog fragment do something and come back to dialog fragment using android navigation component, but after going to fragment when coming back the dialog is gone this is my navigation code

Populate list with instantiated classes dynamically with Kotlin on Android I have an abstract class and all classes in some package derive from it. Is there a way to create a list that dynamically instantiates all these classes that reside in some package when using Kotlin on Android? Here is an example: com.example.service BaseService com.example.service.emailservice GmailService OutlookService All classes in com.example.service.emailservice derive from BaseService abstract class that resides in com.example.service. I want to create a list that contains...

What does junior android developer have to learn in 2019 to be hired? I'm new to android development. Have some experience of dotnet development on C#. What do I need to learn to become android junior developer? The question is mostly about frameworks and approaches.

Sending encrypted file with socket I'm trying to send a file between a pc and an android device using a socket connection. The file transmission works fine, but I get an exception when decrypting the file on the receiving device. javax.crypto.BadPaddingException: error04000089RSA routinesOPENSSL internalPKCS_DECODING_ERROR In particular, I use AES to encrypt the file, then I encrypt the AES key with the public key (RSA) of the receiving device and then I send the encrypted key and the file. The client decrypts the...

Implement OnClick on Menu option of bottom Navigation bar using Navigation Architecture I Have implemented Bottom Sheet Bar using Navigation Architecture Component So now I have 5 options in the bottom navigation bar 4 of them are successfully display fragments but now I have one option when I click it I want bottom sheet to pop up??????? The code written navigates to fragment but I havent attached my bottom sheet to the navigation_graph.xml since it crashes I want to know how to call a bottom sheet using menu option of bottom navigation bar using Navigation Architecture...

`NavigationView.OnNavigationItemSelectedListener` Leaking memory I have a NavigationView.OnNavigationItemSelectedListener inside a fragment and it is leaking memory can somebody suggest me something. Here is the Interface. interface HasNavDrawer : HasToolbar { private val activity: MainActivity get() = fragment.activity as MainActivity private val drawerLayout: DrawerLayout get() = activity.getDrawerLayout() private val navigationView: NavigationView get() = activity.getNavigationView() private val navigationItemSelectListener:...

AndroidStudio - CompileError: (App keeps stopping) -&gt; RuntimeException: Unable to instantiate activity I suddenly have the problem that Android Studio doesn't want to compile my projects anymore. The VD is started and there are no other syntax errors specified, but the app closes continuously. Even if I create a new project and change a little thing there, nothing works anymore. I already searched for the error, but didn't understand exactly which settings were meant, because nobody specified anything. I am relatively new, so I would be very happy if someone could explain this to me in a...

ParseObject: Is there any way how to create JSON from ParseObject? I want to create JSON from ParseObject in my App. Usually If I need to pass object from one class to another, I pass objectId to bundle and I simply call query and return this object. Problem is if you create new ParseObject in offline mode. Calling saveEventually on new ParseObject will not add objectId. ObjectId is null that means I cant query object. The best way would be to send whole ParseObject as String to Bundle and simply recreate it. This is how I worked with JSON objects in past....

How to mock android context using mockk library I am new in JUnit testing on Android and I'm testing a function, which is using android context object to get a string resources and making some comparsions. How can I mock android context object to successfully test this function? For testing I'm using Mockk testing library. private val context = mockk() private val contextWrapper = ApplicationContextWrapper(context) private val objectUnderTest = AppLinkService(contextWrapper) I was trying to mock context using mockk(), but I'm...

Float and Double value substitution is not accurate for some case in Java [duplicate] This question already has an answer here: Is floating point math broken? 30 answers I was making an increment-decrement control in Android Studio. I need to do a very simple subtraction. Then I found some weird result for Float datatypes that is 64.3F-1, found 63.300003. After trying with Double found...

Why LinearLayoutManager.findFirstVisibleItemPosition() of the RecyclerView allways returns 0? I want to get an item position of first visible of the RecyclerView. For LayountManager of the RecyclerView, I'm using LinearLayoutManager. To get item position of first visible of the RecyclerView I am using LinearLayoutManager.findFirstVisibleItemPosition(), but it always returns 0. private lateinit var recyclerView: RecyclerView private lateinit var progressBar: ProgressBar private var arrayList:List = ArrayList() private lateinit var viewModel: ContentsViewModel private lateinit var...

Private field not being set when fragment is created In my fragment I have the following code: class { private val resetHash: String by argument(ARGUMENT_RESET_HASH) override fun onViewCreated(view: View, savedInstanceState: Bundle?) { // resetHash is never set } } The private member resetHash never gets set. Even if I put a breakpoint on the line with private val, it never gets hit. What can be preventing it from being set? I even tried putting a click handler in the onViewCreated method to see if it is set when I click...

What is the meaning of CalculatorImpl in an calculator app? i have an calculator app from github. The name of a class is CalculatorImpl but i donn't know its meanning. This is not a joke question. I just wanted to understand the meaning of the class name. Especially because I'm not an English speaker.

Unable to Cancel the Alarm defined in kotlin I was creating the Alarm by defined below method Intent intent = new Intent(context, AlarmClockReceiver.class); intent.addFlags(Intent.FLAG_RECEIVER_FOREGROUND); Bundle bundle = new Bundle(); bundle.putSerializable(ALARM_CLOCK, dosesReminder); intent.putExtra(ALARM_CLOCK_BUNDLE, bundle); intent.putExtra("MedicineName", dosesReminder.getMedicine_name()); String MedicineTime = ""; if (dosesReminder.getMorning_dosed().equals("1")) { MedicineTime = "1 Morning...

Kotlim UByteArray and System.arraycopy I'm trying to copy array: System.arraycopy(ret, 2, crcArray, 0, crcArray.size) Both ret and crcArray are of type kotlin UByteArray. Code is crashing with java.lang.ArrayStoreException: source of type kotlin.UByteArray is not an array Is there a way to copy ubytearrays using system method or I have to do it manually?

Android Background Task Selection I have an Android "shopping cart" app for business customers to place orders (business-to-business). I'd like a task to run in the background to synchronize items and orders. But I'm having trouble figuring out which of the many options for background tasks I should use (Async Task, Service, Sync Adapter, Jetpack Work Manager, etc). First, some background notes: We are providing the Android phones to customers. The phones are running Android 6 (API 23) I am not concerned about battery...