Questions tagged [kotlin-generics]
18 questions
10
votes
2 answers
Kotlin Generics Error in Java
Given the following three kotlin classes:
abstract class UseCase {
fun execute(action: Action) {
}
}
class ConcreteUseCase : UseCase>()
class Action
I am unable to compile following lines in java…
M-Wajeeh
- 17,204
- 10
- 66
- 103
5
votes
2 answers
Generic function in interface to return concrete implementation
To an interface, I want to add a function that returns an object of the concrete implementation.
So with the interface:
interface Content {
fun cloneMe(): ?
}
and the classes
class Music: Content
class Video: Content
the function…
fweigl
- 21,278
- 20
- 114
- 205
5
votes
2 answers
Kotlin override fun with subtype
Im having trouble inheriting an interface containing a method/fun of a base type, that i would like to override as a subtype in the class implementing it.
So far i have the interface
interface IModel {
fun convert(dataModel:…
nsL
- 3,722
- 3
- 23
- 40
4
votes
1 answer
kotlin generics for Consumer only
Let' say i have this java example:
interface Sink {
void accumulate(T t);
}
public static void drainToSink(Collection collection, Sink sink) {
collection.forEach(sink::accumulate);
}
Notice how the second parameter is…
Eugene
- 117,005
- 15
- 201
- 306
3
votes
1 answer
Passing only types marked as reified to Kotlin generic function
Let's say I have the following code:
open class Fruit
class Apple : Fruit()
open class Juice
class AppleJuice : Juice()
fun > makeJuice(juiceClass : Class, fruit : F) : J {}
I call the function like…
Mindaugas Varkalys
- 141
- 2
- 11
3
votes
2 answers
Inferring parameter of class type with default
I have a class with constructor declared like this
class Facade(
val kClass: KClass = SuperClass::class
)
It is done like this so that developer doesn't have to specify SuperClass if they want to use it instead of a…
Majkeee
- 960
- 1
- 8
- 28
3
votes
1 answer
Kotlin "out" and "in" and generics - proper usage
I was trying to make a generic poor-man's data persistence function that would take a MutableSet of data class and serialize it to disk. I'd like something easy for prototyping, and am OK calling "save()" on the set every so often so that if my…
Benjamin H
- 5,164
- 6
- 34
- 42
2
votes
3 answers
Why can't Kotlin smart cast between an interface and the generic type that is derived from it?
I have the following class:
abstract class PresenterActivity : AppCompatActivity() {
open fun initViewIntent(): I {
return object : ViewIntent{} // type mismatch on this line
}
}
I receive a…
S-K'
- 3,188
- 8
- 37
- 50
2
votes
1 answer
Kotlin generic properties issue
I got some issues with Kotlin when translating my android project from java to Kotlin.
Say i have interface I and interface O which extends interface I.
interface I{
}
interface O: I{
}
And generic class A which have generic parameter V that…
Vlad Morzhanov
- 1,260
- 3
- 14
- 29
1
vote
1 answer
why the translated kotlin code complains about a Array? to be a Array
Having a java class, using androidStudio to translate to kotlin.
Got a error and not sure how to correctly translate it.
The java code:
public class BaseDataImpl extends BaseData {
private final BaseData[] translators;
public…
lannyf
- 9,865
- 12
- 70
- 152
1
vote
5 answers
(kotlin) editText.toString().toInt() isn't work in anroid studio
val editText1 = findViewById(R.id.editText1);
if(comNum != editText1.toString().toInt() ){
View4.text = "오답"
} else View4.text = "정답"
The installed apk is not working. I think edittext.toString.toInt is wrong.
유재언
- 21
- 3
1
vote
1 answer
Why can't make to methods with same name but with different generics?
I'm pretty new in Kotlin language, but I have just encountered some strange behavior that didn't have in other languages, so I wanted to ask why I can't do something like this:
fun methodName()
{
// whatev~
}
fun methodName()
{
…
Patroklo
- 516
- 4
- 15
1
vote
1 answer
How to have a class with a self type paramter as interface in kotlin
I have a class Element with a Self type parameter
interface Element> {
val rules: Set<(Self) -> Boolean>
}
How can I now create a List with Element as type parameter because the following doesn't function of course.
val…
nikolausk
- 31
- 2
1
vote
0 answers
Kotlin generic issue, should be subtype of Nothing
I'm writing a simple Spring test on Kotlin and have a compilation error with generics that I can't understand. The function is below:
@Test
fun actuatorRootReturnsOnlyAllowed() {
val expectBody:WebTestClient.BodySpec
yyunikov
- 5,719
- 2
- 43
- 78
0
votes
1 answer
Can I extend Comparable in Kotlin?
I wanted to implement min()/max() aliases for the Kotlin's ComparablecoerceAtLeast()/coerceAtMost(), if nothing else for the exercise of extending an Interface (I've only extended classes so far).
I tried this:
fun Comparable.max(other:T) :…
Travis Griggs
- 21,522
- 19
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- 167