Remove character from string in Kotlin I am trying to create an Android calculator which uses strings in Kotlin. My problem is how do I delete a comma (or the negative) if it already contains one. Here is my code, it adds the comma correctly but doesn't delete it if user clicks again: if (!buClickValue.contains(".")) { buClickValue += "." } else { buClickValue.replace(".", "") } } or here is my <a...

Kotlin code "Do not place Android context classes in static fields" complaint I have an Android Studio based application written in Java. I works fine and does not cause Android Studio to complain about anything: public class MainActivity extends AppCompatActivity { static Context maincActivityContext; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); mainActivityContext = getApplicationContext(); ... } /* JNI function called from c++ */ private void updateStatus(String event, final String...

spring jar bootRun causes GraphQL Schema error When I build my Spring Boot application using gradle bootRun or build and then run the output jar, I get the following enormous list of errors out of the console log. 2018-03-18 004938.754 ERROR 228 --- [ main] o.s.boot.SpringApplication : Application startup failed org.springframework.context.ApplicationContextException: Unable to start embedded container; nested exception is org.springframework.boot.context.embedded.EmbeddedServletContainerException: Unable to...

Failiing regex in kotlin - WHY? I am struggling to understand why the following code returns false "^.+[\\n]{0,2}".toRegex().matches("This is some text\n\nNote again please fix me") I have tested the regex in regexr but it works fine there... Please help me. In particular I think the ^ to denote at the starting of the string is not working properly because passing an argument of "This is some text\n\n" returns true. THanks

What is a good data transfer file format? Essentially i am writing an Android app that has the user put in information by both selection from lists and writing themselves. Next the information gets sent to a server(my laptop in this case) which uses IText to transform the information it received into a pdf. For that it uses preprogrammed procedures aka if it sees X item marked then it will set up a pdf section for X and fill it with the information associated with X. My problem right now is what i should use for storing and...

Using a database index in a JpaRepository with CockroachDB crashes on subsequent restarts Using a database index in a JpaRepository with CockroachDB crashes on subsequent restarts The following minimal example using a database index with Spring Boot, Hibernate, JpaRepository, CockroachDB and Kotlin fails to restart. It works fine without the database index. ./src/main/kotlin/ThingService.kt: package things import org.springframework.boot.autoconfigure.SpringBootApplication import org.springframework.boot.runApplication import javax.persistence.Entity import...

Collect to map skipping null values How to collect to Map from List where null values are excluded/skipped? This code doesn't skip null values: val map = listOf(Pair("a", 1), Pair("b", null), Pair("c", 3), Pair("d", null)) .associateBy({ it.first }, { it.second }) println(map) Workaround solution. But collects into mutable map: val map2 = listOf(Pair("a", 1), Pair("b", null), Pair("c", 3), Pair("d", null)) .mapNotNull { if (it.second != null) it else null }.toMap() println(map2) So is there more...

Not able to upload file to server in SpringBoot Application with backend kotlin and frontend angularjs The application is working fine on the localserver but when it is deployed to server the file is not getting uploaded Below is the code var pathString = "upload-dir"; var dirUpLoad = File(pathString); if (!(dirUpLoad.exists())) { dirUpLoad.mkdirs(); } var path = Paths.get(pathString); var fileStatus = Files.copy(uploadFile.getInputStream(), path.resolve(uploadFile.getOriginalFilename()), StandardCopyOption.REPLACE_EXISTING) Above is the code but it is...

how to create data base Local Kotlin I make a KOTLIN application that reads information from a database, but I do not know how. I want to create a DB that contains ID, Titles, Articles, Categories, the information will be saved on this database and afterwards displayed on a listView

Is java.lang.Math compatible with kotlin.math? I was learning Kotlin and ran into this issue in Math class: The java.lang.Math and kotlin.math are not compatible. This is for me a little bit awkward and confusing since Kotlin claims that it is 100% compatible with Java. Maybe this is only me who is feeling it is confusing, but I would like to hear community opinion to confirm if my feeling is correct. The issue is the rounding of a number. Please observe the following simple Kotlin code: fun main(args: Array) { val neg = -152.5 val...

How to make the UI dispatcher resume the continuation immediately I've been heavily using coroutines in my Android project. For example, I use them to hand off blocking calls and CPU-intensive tasks to a threadpool. This is where launch(UI) works perfectly: it ensures the continuation resumes on the UI thread. I'm also using coroutines for stuff like awaiting for the first onDraw call, resuming the animation loop with a postOnAnimate(), etc. In these cases the UI context falls short of what I need because it resumes the continuation asynchronously, by...

Hibernate and using @GeneratedValue with CockroachDB results in SQLGrammarException The following minimal example using a generated id with Spring Boot, Hibernate, JpaRepository, CockroachDB and Kotlin produces an org.hibernate.exception.SQLGrammarException. I also tested with PostgresSQL instead of CockroachDB and this is fine. |------------------------------------------------| | | PostgresSQL | CockroachDB | |-----------------+---------------+--------------| | no generated id | OK | OK | | generated id | OK | ERROR...

Pass Kotlin function with undefined parameter as argument From the Kotlin documentation on the Higher-Order Functions: fun lock(lock: Lock, body: () -> T): T { lock.lock() try { return body() } finally { lock.unlock() } } Let's examine the code above: body has a function type: () -> T, so it's supposed to be a function that takes no parameters and returns a value of type T. It is invoked inside the try-block,...

Serializing a Kotlin delegate with Gson I have a Kotlin object that I am trying serialize with Gson. A member that is setup as a delegate does not get serialized. The delegation works if I call it directly, as does the onChange callback, but Gson just ignores it. Is there any way to get Gson to serialize this without writing a custom serializer? Here is a simplified example of what I'm trying to do: class MyDelegate() { fun getProperty(): String { return "myDelegate Property" } fun...

using Geocoder.getFromLocation() in separate Thread whene i use this class and Method: val geocoder = Geocoder(context, Locale.getDefault()) val addresses = geocoder.getFromLocation(latitude, longitude, 1) i use it in this way: fun LocationCallBack(): LocationCallback { locationCallback = object : LocationCallback() { override fun onLocationResult(locationResult: LocationResult?) { locationResult ?: return if (MyFirebase.isInternetConnection(context)){ for (location in...

Expandable ListView Inside a ScrollView I have created an Expandable ListView inside a ScrollView. When I want to scroll inside the Expandable ListView I have to select it and hold it down whilst I scroll otherwise the entire page will scroll. Here is my code...

How to send from server arbitrarily to a STOMP end point in SpringBoot I'm writing a bridge application in SpringBoot two bridge an internal messaging protocol over to a websocket based stomp setup. I'm operating in a mixed-mode Kotlin, java project (which "might" be making things difficult). My goal is when I receive a message on our internal messaging queue, i wanted to send it over to the STOMP endpoints. I can send from STOMP->STOMP and REST->STOMP but I seem unable to make the server send directly to a stomp endpoint correclty. I've gone through just...

Kotlin Android Coroutines - suspend function doesn't seem to run in the background I feel like i'm missing some crucial part to my understanding to how this code below is working: private fun retrieveAndStore() { launch(UI) { val service = retrofit.create(AWSService::class.java) val response = service.retrieveData().await() store(data = response) } } private suspend fun store(data: JsonData) { val db = Room.databaseBuilder(applicationContext, AppDatabase::class.java, "app-db").build()...

Using concatMap to run a Single before running another observable Android Studio 3.1 RC 2 kotlin 1.2.30 The signature of the fetchMessage in Java Single fetchMessage(final String Id); The kotlin code fun translate(Id: String): Completable { return repository.fetchMessage(Id) .flatMap { Single.fromCallable({ update(messageId, it, State.COMPLETED) State.COMPLETED }) } .onErrorReturn({...

Android rxjava toList() not returning data I have an Observable getting data from a String array. Each string is an id so i want to query my database table with that array and get an object. Finally i want to add the objects found in a list and return it in the subscribe() .Above i have the code i try to do it val temp = Observable.from(plan.components) .flatMap { id -> subscriptionRepository.getComponentByUuid(id) .filter { component -> !component.enabled } }...

Does Kotlin guarantee that a range check doesn't instantiate a Range? In my Android app, I wrote return x >= rangeStart && x

Managing custom models with list attributes as documents with subcollections I have a Contact model which holds different attributes and lists of attributes. Now i want to store these in Firestore but with the lists as subcollections of the respective document. A minimal example of the Contact model looks like this (note that the list is excluded from the map): class Contact(private val map: MutableMap){ var nameDisplay:String? by map var nickname:String? by map var organisation:String? by map val phones:ArrayList = ArrayList() } With this...

Cannot add task ':jacocoTestReport' as a task with that name already exists I am trying to add the following task so that I can get some coverage data in my java + kotlin project (for what it is worth, this is a gradle project)... but I get the following error : "Cannot add task ':jacocoTestReport' as a task with that name already exists" Here is the actual task I am trying to add : task jacocoTestReport(type: JacocoReport, dependsOn: "testDebugUnitTest") { group = "Reporting" description = "Generate Jacoco coverage reports for Debug build" reports {...

kotlin dagger retrofit field injection When trying to inject field variables using dagger I'm getting null. Here are the files. Some are in Java and some in Kotlin App.java public class App extends DaggerApplication{ @Override protected AndroidInjector

How to pack Reason and Ktor apps together in a bundle with Gradle? I have the following structure: / -> root /react-app -> Reason app (initialized using cli) /webapp -> gradle app, maven structure with Gradle build file I am not sure how to build everything so I can: run server locally so I can debu make production tar (using the application plugin) My idea is to have 2 gradle modules, but that would work for ktor and not for reason. And even then, not sure how I can develop locally? The second idea is to have everything...

best report framework for tornadofx and spring my app is a simple erp server with spring boot and tornadofx as client in future i will add a web client i search for report framework that can generate reports and export for several format my need is to develop reports in the spring boot server and can run it using tornadofx - will use web view- and using my web client i already take a look in jasper, Bert dynamic report and dynamic jasper but no one of them using kotlin or no tutorial for this any advise thanks

Android - Hide keyboard on Android 8 I'm having troubles with hiding the keyboard on Android 8. I used this before and it worked for the older androids: val view = activity.currentFocus if (view != null) { val imm = activity.getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager imm.hideSoftInputFromWindow(view.windowToken, 0) } Android 8 just ignores it and shows the keyboard anyway. Probably making the input field unfocusable would help, but I really need it to be focusable, so...

Kotlin Spring Jdbc Cannot Use NULL I have the following method in a Spring Boot application using Kotlin. It won't compile because addValue method takes String paramName, and Object value. In my case passing NULL is a valid case, because I want all bankers, not ones from a specific branch. Is there anyway to work around this in Kotlin. override fun getBankers(branchId: UUID?): Iterable { val query = this.sql.getProperty("banker.selectByBranch") val params = MapSqlParameterSource() .addValue("branchId",...

Difference between using Kotlin ans Flutter i need a detail and in depth explain to technical difference between using native kotlin and flutter, Thank you very much : Kotlin Vs Flutter

How to delay to assign a value to a val in kotlin? I define mContext as val and I need to assign a value to it in the fun onCreate. The code private lateinit val mContext: Context isn't correct, how can I do? class UIMain : AppCompatActivity() { private val mContext: Context override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.layout_main) mContext = this } }