StackOverflow Error when implementinf DoublyLinkedList I am implementing doubly linked list using kotlin. But I am getting StackOverflow Error fun push(value:Any) { val newNode = DNode(value =value ) if (isEmpty()){ tailNode = newNode }else{ headNode?.prevNode = newNode } newNode.nextNode = headNode headNode = newNode length++ } after 1st element push it is showing Exception in thread "main" java.lang.StackOverflowError. Why this is happening any ideas.

Android kotlin two way databinding on androidx.viewpager.widget.ViewPager::currentTab I've tried tutorials on the Internet to add adapter on androidx.viewpager.widget.ViewPager to get two way databinding on current tab. I arrived to that adapter // adapter file @BindingAdapter("currentTab") @JvmStatic fun setTab(pager: ViewPager, itemLiveData: MutableLiveData) { itemLiveData.value?.let { if (pager.currentItem != it) { pager.setCurrentItem(it, true) } } } @InverseBindingAdapter(attribute = "currentItem") @JvmStatic fun getTab(pager:...

Display LeaderBoard and Achievement Screen with Kotlin Language i'd like to create two button that on click shows the Leaderboard or the Achievements. I use this code to show the leaderboard and it works on the Android Emulator but not on my smartphone with an internal test or the apk, do you know why? private fun showLeaderboard() { GoogleSignIn.getLastSignedInAccount(this)?.let { Games.getLeaderboardsClient(this, it) .getLeaderboardIntent(getString(R.string.leaderboard_id)) .addOnSuccessListener { intent ->...

Firebase push notification is not working in android kotlin and PHP i am trying to send push notification from my android device through my server, so i have wrote kotlin code for getting token from firebase and stored it into my server. next step i wrote php script to fetch stored tokens from my server and send message command to firebase. i have tested the same API using postman and u got the success message {"multicast_id":7524239394194034238,"success":1,"failure":0,"canonical_ids":0,"results":[{"message_id":"0:1587205979775713%03eb2b8403eb2b84"}]}[]...

I am using bottomsheet inside expandable recylerview it is not scrolling, bottom sheet scroll only works I have bottom sheet contains two fragments, In filter fragment I’m loading the expandable reyclerview ,but does not scrolling Layout is like NestedScrollview -Linearlayout -Reycycler view - Reycycler view (Inside adapter I’m loading one recycler view Can you help me on this

How to tell which property differs when assertEquals fails (Kotlin data class)? I have a test comparing two objects from the Client data class: assertEquals(expectedClient, returnedClient) When I get an error (red state), it's a bit annoying to find the different property: Expected , actual . In this case, it was importer property... but it's time consuming. And I have data classes with more properties which makes me waste lots of time. Considering the default implementation of equals data classes in Kotlin (compares each property), is there any library to...

adding gardient color in kotlin Android - Kotlin - Gardeint Im trying to add nice gardient color to the notification adapter. but for some reason its not working. I think but not sure , that I need to add another XML file . but im dont know how to connect all and where I need to add the file if I need to add. right now I create 2 files 1. XML file in Color --> gardient Notifiacation adapter --> I call the file (title.context, R.color.gardient) what I missing? <a...

reduce lat / long distance per meter Assuming I have two locations referenced in LAT/LOT from: lat 51.504870000000004, lng -0.21533000000000002 to: lat 51.50475, lng -0.21571 Distance between them is 0.02949062526738975 KM. The rounded distance 0.03 KM. private fun calculatesDistance(from: Coordinate, to: Coordinate): Double { return if ((from.lat == to.lat) && (from.lng == to.lng)) { Double.MIN_VALUE } else { val theta = from.lng - to.lng var dist =...

Android Bluetooth Low Energy: No advertising device (phone) is detected while scanning I am creating an android app to estimate distance between 2 devices based on bluetooth low energy rssi signal. I performed following steps so far: I created a class BleAdvertiser to enable a specific service advertisement I created a class BleScanner to scan existing devices and extract all data needed (device name, device mac address, rssi and txPower ( if provided)). For that I am using bluetoothScanner.startScan()/stopScan() and I am fetching the data needed inside onScanResult...

File upload in the background Android What is the best way in Android to upload files to firebase storage from the background even if the app isn't running/in the recent app menu?

Kotlin code duplicates a line in console on its own (looping through a function without taking user input) Let me first put the code then explain: fun main() { loop@ while (true){ println("Input the action (add, remove, import, export, ask, exit):") val userInput = scanner.nextLine() when (userInput){ "add" -> add() "remove" -> remove() "import" -> import() "export" -> export() "ask" -> ask() "exit" -> { print("Bye bye!") break@loop } }...

Android KTX: how to override Kotlin added property extension I am trying to override View.setRotation() method in Kotlin. Since AndroidKTX already provided property extension "rotation", caller's can simply call viewObject.rotation = 90.0f to rotate the view. However, I want to add some additional operation when user change the rotation, like override fun setRotation(newRotation: Float) { if (rotation == newRotation) return rotation = newRotation doSomethingElse() } This will crash because of StackOverflow error. So, I have...

How to pass data to ViewModel from AutoCompleteTextView? I need to pass an id of clicked object from AutoCompleteTextView to ViewModel. Here I have a binding adapter to set a spinner with objects for AutoCompleteTextView. @BindingAdapter("bindAutocomplete") fun bindAutocomplete(textView: AutoCompleteTextView, cities: List?){ cities?.let { val adapter = ArrayAdapter( textView.context, R.layout.support_simple_spinner_dropdown_item, it) textView.setAdapter(adapter) } } My question is: where should I place my...

forget key and how to use pem file I loose project's private key and I should update the app. So I get this file pepk.jar from android console and get the .pem file by using this command java -jar pepk.jar --keystore=key.jks --alias=key --output=key.pem --encryptionkey= * When I use .pem file as key with the project I got this message com.android.ide.common.signing.KeytoolException: Failed to read key key from store "/home/khalid/key2.jks": Invalid keystore format How can I solve my problem ? I need to get the key...

Pass the values to another activity in Kotlin The MainActivity.kt recieve the latitude and longtitude val intent = Intent(this@MainActivity,MapsActivity::class.java) intent.putExtra("latitude", latitude) intent.putExtra("longitude", longitude) And then pass to MapsActivity.kt val intent = Intent(this@MapsActivity,MainActivity::class.java) val lat=intent.getStringExtra("latitude").toDouble() val lon=intent.getStringExtra("longtitude").toDouble() And when I run the application I get a errors while I go to...

How to resolve bindings with different scopes? I have a model (AModel) which I wanted to use as singleton. I created a custom scope named @ApplicationScope to use it for every class I need only once. So AppComponent and AModel shares this @ApplicationScope. I have some fragment (ConfirmationFragment) where I would like to use both AModel and BModel. BModel has a different scope because I'd like to use it in 3 fragments but Amodel needed everywhere. The idea to access both AModel and BModel was to let ConfirmationComponent depend on...

Only two first strings in ArrayList&lt;String&gt; are passing via intent. The rest is gone I am building an app using flutter but I need to use Kotlin to access the setAlarmClock() method. On the MainAcitivy.kt I get some lists from the dart code and everything is good. But when I pass the lists to the BroadcastReveiver via Intent, the lists contain only the first 2 Strings and the rest is gone (the ArrayList size is 2). This is the MainAcitivy.kt file: import android.app.AlarmManager import android.app.PendingIntent import android.content.Context import android.os.Build import...

Merge two maps into one I have to maps. One is Map, like "USA, 55.87". Second is Map, like "USA, United States of America". And I want to turn this maps into Map. Where Result contains two String, like "USA, United States of America". How to do that?

How to return a Singleton from a getter function using Koin I have the following CurrentWeatherResponse class which contains the location field that uses a getter to return an instance of WeatherLocation() using the class's constructor params. How would i go about making sure that this getter will always return a singleton of the WeatherLocation class using Koin in a module file? data class CurrentWeatherResponse( // Tells GSON that the "currently" field of the JSON returned by the // API should be tied with our CurrentWeatherEntry data...

Why is the savedInstanceState Bundle of my Android Fragment empty on restore? In the Android app I am developing I have a list fragment that shows a Recyclerview of list items. The first time we load it retrieves the list from a url, but it's not going to change frequently enough to keep reloading it so I want to retain the data. As far as I can tell the Android way to do this is using the savedInstanceState for the fragment, like this: class ItemListFragment() { private var itemCards: RecyclerView? = null; public val Items: ArrayList = ArrayList()...

Kotlin return null safe value from null-able value I have this function fun safe(t: T?): T { return Optional.ofNullable(t).orElseThrow { IllegalStateException("safe value should not be null") } } I use it to say I know that T is not null now so give me back the non null-able form of it. So I use it like this, I declare class SomeType(val someOtherType: SomeOtherType?) But some someOtherType in another place is declared like so: class SomeThirdType(val someOtherType: SomeOtherType) So in SomeType I have this function: class...

getvalue from Firebase to arraylist and add in ListView i want getvalue from firebase to arraylist and display on ListView but it give to me crush i don't what is the reason but i hope someone can help me this is code getvalue from firebase to arraylist override fun onStart() { super.onStart() val database = FirebaseDatabase.getInstance() mDatabaseReference = database.getReference("bus") mDatabaseReference?.addValueEventListener(object :...

android kotlin categories subcategories I have been working on a project which includes categories and subcategories. The problem which I've got is that once I click on category from the list I receive the list of subcategories but I can't work out a way to get the specific id of the subcategory. Each time I click on a subcategory, in logcat I receive O. Could I ask you to help me with this. @get:GET("api/catsubcatresponse") // val getcatsubcatresponse:Observable // catsubcatresponse class CatSubCatResponse { //...

How to pass values in AudioVisualization View through clicking on a button in another fragment? AudioVizualization View in SongsPlayingFragment.xml I have created this ThemesFragment. By clicking on these radiobutton , user could change the color of waves and background color of audiovisulization view. But I am finding it very difficult to implement this and pass the new array of colors and new background color in my ThemesFragment.kt file. Need help...

How to define function that I pass as a param as a nullable? According to this answer I can pass function as a param https://stackoverflow.com/a/33402863/5709159 fun foo(m: String, bar: (m: String) -> Unit) { bar(m) } // my function to pass into the other fun buz(m: String) { println("another message: $m") } // someone passing buz into foo fun something() { foo("hi", ::buz) } So, there are actually two questions If is it possible define bar function as nullable in order to...

Best way to hide soft keyboard on touch outside ANY editText I searched everywhere for a solution to this problem, I hope you can help. I need to hide the soft keyboard when the user touches outside ANY EditText (not just the one currently focused). This is what I did so far: override fun dispatchTouchEvent(event: MotionEvent): Boolean { if (event.action == MotionEvent.ACTION_DOWN) { val v = currentFocus if (v is EditText) { val coords = intArrayOf(0,0) v.getLocationOnScreen(coords) val x =...

foreach kotlin waiting for intervals to follow the flow Can someone help me in the following: I have a FOR and inside it I run some TIMERS my intention is that initially it runs the TIMER for the first index and only after the timer is canceled does the method go to the next timer. my FOR would need to wait for the TIMER to be finalized. for (i in 1..10) { println("running for loop: $i") val timer = Timer("timer: $i", true) timer.schedule(100, 1000) { println("${LocalTime.now()} to loop: $i") //...

Can't return body of http request So I'm trying to return the body that I retrieve in OnResponse(). I can see in the debugger that the body is retrieved but doesn't get assigned to result and handleHttpRequest() returns ""? The only way that I can send the body String to parseJsonToObject() is by calling it in onResponse witch I don't want to because I want to use handleHttpRequest() for other JSON requests. What i want to do is to return the body in handleHttpRequest and call parseJsonToObject() in doInBackground(). My...

Kotlin Basic Cronometer Bug , Give Advice to Newbie I have 2 button and 1 textview in my layout. I had just trained, but saw some bugs. When users starts the cronometer they can unlimited click on the start button how can i fix it ? I'm really newbie in the android development. Can you give advices for me, while i was watching my udemy lesson, i could catch the codes and basics. After that, when i try to build some basic projects for improve my skills, it gets hard. I have many syntax errors. I know what to do, but I'm confusing the order....

Jackson with Kotlin: how to serialize only annotated properties I'm trying to start using Kotlin in my existing Java project, but Jackson is returning empty ({}) JSON objects when serializing Kotlin objects (whereas it works perfectly with Java objects). One important requirement I have is that I only want to serialize the fields that have been annotated with @JsonProperty (hence why I turn off AUTO_DETECT below). Here is the test code: public static void main(String[] args) throws JsonProcessingException { ObjectMapper mapper = new ObjectMapper()...