item in array or array.contains(item). What made me laugh was https://stackoverflow.com/questions/42234775/kotlin-idiomatic-way-to-check-array-contains-value. The posters seemed to want to find the cleverest, most complex way of doing it rather than answering the question. 'item in array' seems the most elegant but is it idiomatic?

I think the accepted answer is pretty reasonable, I don't quite get why this doesn't answer your question. Basically you can use both depending on how readable you find them. I usually use

in

inside

if

conditions because I like how it reads. Sometimes

contains

might feel more natural if it's at the end of a chain of calls. In other cases, I don't mind, I guess it's opinion based anyway

item in array

is idiomatic

Thanks

the Kotlin method is

inventory.removeAll { it.name == name }

removeIf

comes from Java

removeIf

seems to work on

mutableListOf

🤔

you must have set something up wrong;

removeIf

is one of the new default methods in Java 8: https://docs.oracle.com/javase/8/docs/api/java/util/Collection.html#removeIf-java.util.function.Predicate- and as such it is callable on a

MutableList

as long as you're on JVM

OK, but removeIf still red. Think I may need to use removeAll, just looking into syntax

seems to work on my machine at least 🙂

data class Thing(
        val name: String
    )

    val inventory = mutableListOf<Thing>(Thing("foo"), Thing("bar"), Thing("baz"))
    println(inventory) // [Thing(name=foo), Thing(name=bar), Thing(name=baz)]
    inventory.removeIf { it.name == "foo" }
    println(inventory) // [Thing(name=bar), Thing(name=baz)]

But I can do it with

fun dropLoot(name: String): Boolean {
    println("$name will be dropped")
    return inventory.retainAll { it.name != name }
}

that may mean you don't have jvmTarget="1.8"

Thanks, where do I find my jvmTarget? I'm using the latest Android Studio.

@Ben Edwards it should be in one of your

build.gradle(.kts)

files - or nowhere at all, but I think the default is now 1.8 so if you have no such setting you should also have no such problem 😄