The new Java stuff is nice, but to be true, code written with it simply looks ugly. In a big team with different skill levels, this leads to pure chaos.

Are we going to have a beginner class ?

so im trying to write a lambda function that returns a bool but the compiler think that it ment to return Unit anyone knows how i can fix it?

{
for (t in channels!!)
    if (t.item1 === message.channelReceiver)
        return false
    return true
}

so, like, you cant return in the middle of a lambda? only at the end?

I think by "backing field" they just mean backing property. That confused me as well when reading through - if we're using strict language saying that everything is technically a "property" instead of a "field" then don't talk about fields in the same paragraph. Might be worth clarifying

because now I have to use

val x = y
if (x != null) {}

@diesieben07 Java does bad things with generics a lot, Kotlin is very strict. The code you "cannot change" is bad and sets up an un-winnable situation for Kotlin. It isn't a bug in Kotlin. You give it a type T basically of

*

which means nothing useful. There is a big lack of information. At any point do you know what type T is? and if not, how does the

parseProperty

expect to work on unknown types, does it check against a list of instance types then performs its action? If there is no way to know outside of this function what type type is, then you need to change

parseProperty

to accept

<*>

as the type as well because you cannot say "give me a type T" to someone who can never know what is the type of

T

How do I map / use access modifiers concept of JAVA in kotlin? 🤔 Any pointers...

Is it possible to pass the string data from the

Sender

class all the way to all the classes that implements

Clickable

interface Clickable {
    fun click(message: String)
}

class Sender {
   init {
       Clickable.click("sending from 'Sender'") // is this possible?
   }
}

class Button : Clickable {
    override fun click(message: String) = println("button $message") // receiving the message here
}

when you use

as?

that will effectively wrap it in a try catch and return null if the cast fails

I always do mine here: http://regexr.com/

Is there a equivalent to the replaceAll { } function on a ArrayList in Kotlin? (which mutates the array directly, when using for example a map { } I would have to assign the result back do the array or do a clear / addAll)

Ended up doing a extension myself, but would gladly replace it with a library function

fun <T> ArrayList<T>.transformAll(transform: (T) -> T) {
    for(i in firstIndex..lastIndex) {
        this[i] = transform(this[i])
    }
}

@Test
    fun `Should apply the transformation to each element of the array list`() {
        // GIVEN
        val list = arrayListOf(2, 3, 4)

        // WHEN
        list.transformAll { it * 2 }

        // THEN
        assertThat(list, `is`(equalTo(arrayListOf(4, 6, 8))))
    }

Am i missing something, or '\s' is not valid "single-space" in kotlin?

how to escape

$

in triple quote?

Any idea what should go in those extension function?

Might there be a better way to convert a

ArrayList<>

to

vararg

parameters than

*arrayList.toTypedArray()

?

println((1..5).map {"*".repeat(it)}.joinToString(separator = "\n"))

you don't get much more cryptic than that

@ice32 i made a web-framework for java/kotlin inspired by express.js: https://javalin.io/documentation

to use both java and kotlin in the same project

I want to provide the methods that ScriptEngine provides as well as the methods that Invocable provides by delegating to either of those two objects.

anybody knows a nicer way to do this:

val childUnitsById = units
                .map { if(it.parent != null) it else null }
                .filterNotNull()
                .groupBy {it.parent!!}

Hi! I got a custom self-made database library (java) which provides a

SqlServer

object for basically everything needed to interact with our database. In Java, we stored that reference in a static variable, as it was accessed and needed in a lot of different places. As there is no "static" in Kotlin, I'm unsure about how do do it properly.

class Database { val sqlServer = SqlServer(...) }

Does not work, as I can't access it from somewhere else

class Database { companion object { val sqlServer = SqlServer(...) } }

Does not work, as I can't pass any configuration

object Database { val sqlServer = SqlServer(...) }

Does not work, no support for constructors or similar

In Java, we do this:

public static void main(String[] args) {
  DbConfig dbCfg = new DbConfig(args);

  Database.init(dbCfg);

  //Database ready to use
  Database.select(...);
}

It would be nice to store the sqlServer object immutable and as a nonnull value. Maybe i'm just dumb rn, it's sort of my first kotlin project. 🙂 Thanks!

Hey guys, can I modify a private variable in a class via an extension of that class?

What tould be a good kotlin way to perform multiple (but same) comparisons with a object?

fun isNewTarget(touched: Draft) = touched !== sourceTouched && touched !== targetTouched

might it be possible to simplify this?

and a more basic question, what do people use for unit testing?

New to kotlin, wanna build kotlin from source and see how it works(eg: compiler or so), but I get problem when I try to build on my Mac OS, is there any tutorial in detail about build kotlin from source code?

Why the hell is the suppressing not working