Kotlin protects you from mistakenly operating on nullable types

fun foo(): String {
    null?.let {
        return it
    }
}

println(foo().length) //NullPointerException

goto

String::class

KClass<String>

"Hello"::class

KClass<out String>

"Hello"::class

KClass<T>

T

String

String

getValue(receiver, property)

var value: Boolean

var value: T

String?

Inheritance from an interface with ‘@JvmDefault’ members is only allowed with -Xjvm-default option

default

CharSequence.reduce

File.copyTo

overwrite = true

FileAlreadyExistsException

list.subList()

toIndex

//have
val list = listOf(1,2,3,4)

//want sublist
listOf(3,4)

const matches = str.match(/[aei]/gi)

a

e

i

out

longArray.toList().groupingBy{ it }.eachCountTo(sortedMapOf())