Room db migration fallbackToDestructiveMigration() not working I am using Room with a prepopulated database in the assets folder. For an app update, I would like to alter this database by adding a new column and prepopulating this column with new data. The database was auto-migrated from version 1 to 2 (a table was added). From version 2 to 3, I would now like to apply abovementioned changes by providing a different 'database.db' file in the assets folder and allowing for destructive migration. @Database(entities = [Object1::class, Object2::class],...

Why can the author assign the fun launchDetailsActivity which accepts two paramaters to OnExploreItemClicked which accepts only one paramater? The following code is the project. typealias OnExploreItemClicked = (ExploreModel) -> Unit accepts only one paramater fun launchDetailsActivity(context: Context, item: ExploreModel) accepts two paramater. I don't understand why onExploreItemClicked = { launchDetailsActivity(context = this, item = it) } is right, could you tell me? class MainActivity...

What could be the cause of this error? (Kotlin) (AndroidRuntime: FATAL EXCEPTION: main) I got the following error while debugging my app: E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.studycountdowntimer, PID: 16161 java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.studycountdowntimer/com.example.studycountdowntimer.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.pm.ApplicationInfo android.content.Context.getApplicationInfo()' on a null object reference at...

Where is the object of ExploreModel created? The following code is the project. I don't understand fully the code onExploreItemClicked = { launchDetailsActivity(context = this, item = it) } in class MainActivity . The fun launchDetailsActivity requires two paramaters which are Context and ExploreModel. One of paramater is Context which is assigned with this, it's OK; Another of paramater is...

Publishing messages to AWS SNS with Micronaut and Kotlin I'm tryin to send a list of objects to an SNS topic, with Micronaut and Kotlin. Following the documentation https://micronaut-projects.github.io/micronaut-aws/latest/guide/#sdkv2 I added implementation("io.micronaut.aws:micronaut-aws-sdk-v2"). accessKeyId, secretKey, sessionToken and region to the application yml file. Added implementation("software.amazon.awssdk:sns") After which...

App stuck while trying to authorize health kit i'm trying to get authorization for my app in order to be able to read and write heart rate for a huawei smart band. However, every time i start the app it gets stuck on the login screen as soon as the request for authorization begins... The app is not being redirected to anywhere to give authorization, its just stuck and im not able to get any kind of response from my app, even the buttons from the login screen are non responsive. Here's the login code where i'm asking for authorization....

Google Silent Sign In Failing In my Android application, I'm using Firebase Authentication to allow users to sign in with their Google account. I have a "Delete Account" option that will remove the user from Firebase. According to Firebase's documentation, for removing a user it is suggested that the user should be re-authenticated in order to successfully delete the user from Firebase. However, tokens...

In Android WebView Print Document Automatically Saved pdf without any button click of pdf on WebView Print Document? I am making a webview application and open some HTML URLs but I want to save it as pdf in the internal storage of android. I want to save pdf without any click of a button of a print document. here is my code image whose open pdf print document on webview is possible save any button click

How to POST multiple files in one Request using VolleyMutlipart in Android Studio? I have a function that takes file name and its Uri then send that file to the server. Here it is private fun uploadFile(pdfname: String, anyfile: Uri) { var iStream: InputStream? = null val myurl = "https://apiurl" var rQueue = Volley.newRequestQueue(this) try { iStream = contentResolver.openInputStream(anyfile) val inputData = getBytes(iStream) val volleyMultipartRequest: VolleyMultipartRequest = object :...

Mark all as read button for recycler view android Hi I'm wondering how to mark all items as read on button click in recyclerview android

Cannot load Google map in Kotlin Fragment? I need to load a google map into fragment. Here's my code and it's not working. class busFragment : Fragment(), OnMapReadyCallback{ private lateinit var mMap: GoogleMap companion object { var mapFragment : SupportMapFragment?=null val TAG: String = busFragment::class.java.simpleName fun newInstance() = busFragment() } override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) } override fun...

Storing an ArrayList as a persistent data structure I am developing a todo list app in which I have a ArrayList of categories for the individual todos like Personal, Work etc. This todo list is stored as a persistent storage via Room library. Now I need to provide the functionality to user to create their own lists. For that I need the categories ArrayList to also be persistent. How can I do this?

Android studio kotlin, cannot directly select ID without findViewById() I'm new to android studio and I'm leaning it from this At 50:45 he says that we can directly use the id without findViewById (), for him it shows just import that Id, but when I tried the same I'm not getting what he is getting. Can anyone tell me what's wrong, is that feature removed in the latest update??

How to shorten code when there are many setOnClickListeners() in Kotlin-android? I am creating a calculator. But there are too many setOnClickListeners() making it harder to progress. This belongs to a fragment and it also has a ViewModel. I am using dataBinding here. If there is any way I can write less code in the below mentioned context. if there is any confusion about the question, please write in the comment. If my approach is wrong, share in the comments MY code: override fun onViewCreated(view: View, savedInstanceState: Bundle?) {...

Invalid <color> for given resource value I always get the following error when building: Invalid for given resource value. Failed to compile values file. My Colors.xml: #ffd700 #000088 #fe0000 #8800ff #008800 #ff00ff #00ff00 #0088ff I always called it with resources.getColor(R.color.Sieben) It worked the whole time, I didn't change anything, but suddenly it doesn't work anymore

Android TextView fromHtml() how to support unsupported css style, text size? I'm using this: HtmlCompat.fromHtml(html, HtmlCompat.FROM_HTML_MODE_LEGACY); How to add support of text size regarding a fact that font-size isn't natively supported? I don't want to override whole paragraph text - other styles works well. Using regex or parse html through different library may lead to problems as part of a text may have bigger font or parser may work differently. Also a webview isn't a sollution. Example html: TEST

How to solve this Error:Unresolved reference: text which is related to scope in Kotlin? What I want to achieve: I want to get the button text as parameter for the function What I want: // Operators - setOnClickListener btnDivide.setOnClickListener { viewModel.mountOperator(it.text) } btnMultiply.setOnClickListener { viewModel.mountOperator(it.text) } btnMinus.setOnClickListener { viewModel.mountOperator(it.text) } btnPlus.setOnClickListener { viewModel.mountOperator(it.text) } What is working: // Operators - setOnClickListener btnDivide.setOnClickListener {...

Kotlin multiplatform. Ktor download big file and save to local file I have the kotlin multiplatform mobile app for Android and iOS targets. In the app i need to download a big file (50MB), show progress while download, save it locally, verify with MD5, than read line by line and do some action. As i understand Ktor is best http client for kmm. Also, i found some tips how to show progress. But in all example i found all contents is downloaded to memory and only after this i can save it to file (shared code can not do this, i need to call expect/actual code...

Should initialisation of class-level variable with by lazy in Kotlin be avoided because it prevents Unit Testing? Having a class-level variable and instantiating the object at the same time creates a problem for Unit Testing because you can't really mock the dependency. Does this mean the Kotlin feature by lazy should be avoided as it hinders proper unit testing, or is there a way to overcome this? Thanks.

What is the differnce between MutableLiveData and LiveData in Android-kotlin? [duplicate] What is the differnce between MutableLiveData and LiveData? the code I have written: val currentExpression: MutableLiveData by lazy { MutableLiveData() } val currentResult: MutableLiveData by lazy { MutableLiveData() }

Spring boot "Operation is not supported for read-only collection" when updating a record in database I am fairly new to Spring Boot and unable to find out why my CRUD repository seems to keep throwing an exception saying "Operation is not supported for read-only collection" when sending a request to a Put endpoint. All other repositories seem to work just fine. Here's my code: User.kt package com.karbal.tutortek.entities import com.karbal.tutortek.dto.userDTO.UserPostDTO import java.sql.Date import javax.persistence.* @Entity @Table(name = "users") data class User( @Id @Column(name...

QR Code generator and access to firebase - Kotlin I need to Generate QR code and after generate, scanning that QR code I need to access firebase data. Is there any possible way to make it? I hope to generate QR code using zxing library

Type mismatch: inferred type is String but Regex was expected So, I've converted a code in android studio from java to kotlin and now I'm getting these errors. please Help. Type mismatch: inferred type is String but Regex was expected Task appcompileDebugKotlin in app Finished fun hasDigit(value: CharSequence): Boolean { return value.toString().matches("(.\\d.)") } fun hasUppercase(value: CharSequence): Boolean { val s = value.toString() return s != s.toLowerCase() } fun hasSymbol(value: CharSequence):...

Java - Use music playback control buttons Usually on keyboards there is buttons to stop the current track, go to the next track, or to the previous one. When I'm playing sound on YouTube for example, and press the F10 key, the video stops. I'm creating a Java/Kotlin music player. What currently happens when I have music playing, and then I click F10, is that the last YouTube video I have in an open tab starts playing, and the music player does not get effected at all. What I want is: When I click F10 (or the other control keys), I...

Kotlin- Save live data into an array i have sensors that read in values to a live data value, for example temperature. i want to read in 4 or 5 temperature values into an array and get the average of this array so the shown temperature on the app is more exact. However as the app is constantly reading in data values, i want to read in new data points into an array every few seconds to get a new average. my current approach: fun append(arr: Array, element: Double): Array { val list: MutableList = arr.toMutableList()...

What is the application of "by lazy" in Android-Kotlin? In which places should the by lazy be used? Why should it be used? How does it make the code better for example: val currentResult: MutableLiveData by lazy { MutableLiveData() }

What should be lifeCycleOwner of LiveData-Fragment or Activity? Will Activity be lifeCycleowner of LiveData? or Will Fragment be lifeCycleowner of LiveData?

I'm trying to print a list on the screen using the recyclerview, but the code in the adapter part is not working MainActivity is as follows. Nothing comes out on the screen, but I don't know which part is wrong. How can I add the value of TV_item_name? And in the log, it's from the DetailViewAdapter of the inner class. Log.d (logTag,onCreateViewHolder11iscaled") value is also not output, so what is the problem? package com.example.test_recyclerview import androidx.appcompat.app.AppCompatActivity import android.os.Bundle import android.util.Log import android.view.LayoutInflater import...

How to zoom into a location in google map in kotlin? This's on map ready function. I want to zoom into that location. but using this only can get marker not zoom. override fun onMapReady(googleMap: GoogleMap?) { mMap = googleMap!! val sydney = LatLng(-34.0, 151.0) mMap.addMarker(MarkerOptions().position(sydney).title("Sydney")) mMap.moveCamera(CameraUpdateFactory.newLatLng(sydney)) }

RecyclerView OnItemClick position becomes null in Viewpager Kotlin I have a problem in which correct position of recycler view item is passed to another activity and correct position is caught in the intent. Problem is when I want to create fragment that position becomes null. Any solutions? class MainActivity : AppCompatActivity() { lateinit var recAdapter:RecyclerAdapter lateinit var linearLayoutManager: LinearLayoutManager private var newsList=ItemList() override fun onCreate(savedInstanceState: Bundle?) {...