Sottti

data class User(
        val name: String,
        val surname: String = "",
        val address: String = "") {

    class Builder {
        private lateinit var name : String
        private var surname : String = ""
        private var address : String = ""

Sottti

// Private.kt file

// Visible just inside this file
private const val numberThree = 3

// Visible just inside this file
private class User() {
    // Visible just inside the user class
    private val numberEight = numberThree.plus(5)
}

Sottti

// Protected.kt file

// Visible inside this file
private const val numberThree = 3

// Visible inside this file
private open class User() {
    // Visible inside the User class and subclasses
    protected val numberEight = numberThree.plus(5)
}

Sottti

// Public.kt file

// Visible everywhere
public const val numberThree = 3

// Visible everywhere
public open class User() {
    // Visible to everyone with visibility on the User class
    public val numberEight = numberThree.plus(5)
}

Sottti

// AnotherFile.kt file

// numberThree is visible to any other file because it's public
// numberEight is visible to any other file because User and numberEight are public
// numberEleven is visible to any other file because Moderator and numberEleven are public
private const val numberTwentyTwo = numberThree + User().numberEight + Moderator().numberEleven

Sottti

// Internal.kt file

// Visible to everyone in the same module
internal const val numberThree = 3

// Visible to everyone in the same module
internal open class User() {
    // Visible to everyone in the same module that has visibility on User
    internal val numberEight = numberThree.plus(5)
}

Sottti

// SameModule.kt file

// numberThree is visible because this file is in the same module than Internal.kt
// numberEight is visible because this file is in the same module than User
private const val numberEleven = numberThree.plus(User().numberEight)

Sottti

// DifferentModule.kt file

// ERROR: numberThree is not visible because this file is in a different module than Internal.kt
// ERROR: numberEight is not visible because User() is in a different module than Internal.kt
private const val numberEleven = numberThree.plus(User().numberEight)

Sottti

// User is public
// The User primary constructor is private
class User private constructor(id : Int) {
  // ...
}

// Moderator is internal
// The Moderator primary constructor is private
internal Moderator private constructor(id : Int) {
  // ...

Sottti

// Overridden.kt

public open class User {
    protected open fun getAge() = 16
}

public class Moderator : User() {
  // getAge() inherits the protected modifier as default
    override fun getAge() = 18
}