Kotlin provides the ability to extend a class with new functionality without having to inherit from the class or use any type of design pattern such as Decorator. This is done via special declarations called extensions.
Questions tagged [kotlin-extension]
333 questions
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How to create a generic extension function for an enum class annotated with kotlinx.serialization.Serializable?
Given the following Kotlin enum:
@kotlinx.serialization.Serializable
enum class MyEnum {
@SerialName("One") ONE,
@SerialName("Two") TWO,
@SerialName("Three") THREE
}
I can call the following generated…
JJD
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1 answer
How to shadow member function with a custom Kotlin extension function? (like Kotlin stdlib does)
I am reading Kotlin in Action 2nd edition.
Chapter 3 says:
If the class has a member function with the same signature as an extension function, the member function always takes precedence
At the same the book demonstrates the CharSequence.split…
Kirill
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1 answer
Can I add companion extension without first having companion object within a class?
For the below code, I can add invoke extension to the Companion
operator fun MyValue.Companion.invoke(value: Int) =
MyValue(value.toString())
class MyValue(private val value: String) {
companion object
fun print() = println("value =…
Elye
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1 answer
how to import an extension function in Kotlin?
this is the function i'm trying to import https://developer.android.com/reference/kotlin/androidx/compose/ui/unit/Density#(androidx.compose.ui.unit.DpRect).toRect()
here is my code
val cardWidth = 180f.dp
val cardHeight = 270f.dp
val…
Mars
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1
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1 answer
Android Formatting String in Extension Function
I am trying to get Formatting String in AndroidViewModel by using following extension function but failed:
Version %1$s
val versionText = getString(R.string.version_text, "1.0.0")
fun…
Sam Chen
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2 answers
kotlin-android-extensions not working. what will be the problem?
I was following some guide(download android studio today) of kotlin and I have use the setText and it's not working.
what will be the problem?
package com.example.basic
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import…
kimhaju
- 19
- 6
1
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1 answer
Why is this extension function slower than non extension counterpart?
I was trying to write a parallel map extension function to do map operation over a List in parallel using coroutines.
However there is a significant overhead in my solution and I can't find out why.
This is my implementation of the pmap extension…
Fedelway
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- 2
1
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1 answer
Kotlin extension function failed to compile in java
I've defined the following extension function
fun T.showAppPresentation(
appPresentable: Maybe,
appPresentationView: AppPresentationView,
closeListener: () -> Unit
) where T : Fragment, T : FragmentPresentable {
…
Benjamin
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1
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2 answers
Lint error with snackbar extension function
I have the following extension function to reduce a bit the code and to avoid forgetting the duration when showing a snackbar:
fun Fragment.showSnackbar(text: String, length: Int = Snackbar.LENGTH_SHORT) {
view?.run { Snackbar.make(this, text,…
SergiBC
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1 answer
Kotlin - Is there a way of defining an explicit scope of a function with receiver defined in companion object?
Imagine you have a following code:
interface SomeClient {
fun isValid(value: String): Boolean
}
class SomeData private constructor(
val value: String
) {
companion object {
fun SomeClient.create(value: String): SomeData? =
…
alakida
- 48
- 6
1
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1 answer
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…
Robin
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1
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2 answers
How to create a View extension function in Kotlin
I'm trying to create an extension function in Kotlin. I did try several tutorials, but didn't quite understand, how to implement this one.
I'm trying to create a setWidth() function as such
//Find my_view in the fragment
val myView =…
SowingFiber
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1 answer
How to filter a single list with multiple "cases" in Kotlin
I have a Sealed class as follows:-
sealed class SoundEffect {
sealed class Acoustic : SoundEffect() {
object Active : Acoustic()
object Inactive : Acoustic()
object Disable : Acoustic()
object Enable :…
Hector
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0 answers
How to supply side effect for RxBinding.textChanges() and preserve it's functionality on client side?
Suppose that i'm writing my own View class, that represents editable field and contains EditText tv_input inside:
class EditTextIconItemView : LinearLayout {
fun setInputText(text: String?) {
with (tv_input) {
setText(text)
…
Maxim Alov
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1 answer
Extension property inside class: Unresolved reference: errorResponse
In my android project:
// Extension Properties
val Response<*>.errorResponse: ErrorResponse
get() = ErrorUtils.parseError(this)
class TransportService {
companion object {
private val SERVICE_UNAVAILABLE_CODE = 503
private…
Alexei
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