Hi, could anyone explain what the diff between also and

Question

Hi, could anyone explain what the diff between also and

apply is? like, I have this code

fun main() {
println("Hello, world!!!")
var a = 3
var b = 5
var c = 0
c = a.apply { a to c}
b = a.also { a to b }

print("$a $b $c")
}

but both of them result in c = 3

#kotlin #programming #russian

0

09.05.2020

2 ответов

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Alex Levin

Back to your example: in both cases apply and also will do nothing :) (a to c or a to b will just create pair of two ints but it will not be stored anywhere) So technically your example is something like this but with extra steps: fun main() { println("Hello, world!!!") var a = 3 var b = 5 var c = 0 c = a // c = 3 a to c // will do nothing b = a // b = 3 a to b //will do nothing print("$a $b $c") }

0

09.05.2020

Alex Levin · Accepted Answer

Hi. Documentation for that here: https://kotlinlang.org/docs/reference/scope-functions.html In short: both are scope function and both will return original object (a in your case) Technical difference is in lambda: receiver parameter ( this ) will be in apply lambda scope and usual parameter (implicitly can be called as it ) will be in also lambda. In terms of practical difference - apply usually used to change object itself if that not possible in the constructor. Bad and outdated example is: val list = mutableListOf<Int>().apply { add(1) //can be this.add(1) add(2) } also is usually used to do something with object (store it, print it, etc): val something = foo().also { println(it) }

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Hi, could anyone explain what the diff between also and

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