lateinit is a late initialization for the class field

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lateinit is a late initialization for the class field | Kotlin

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lateinit is a late initialization for the class field | Kotlin

last updated: 2 February 2025

The lateinit modifier tells the compiler that there is no value now, but will initialize later.

Kotlin

class MyBook
{
lateinit var address: MyAddress
}

Example 1 I use lateinit

Kotlin

class MyAddress (val street:String, val country:String)
{
     fun Show() { println("${street}, ${country}") }
}

class MyBook
{
     lateinit var address: MyAddress
}

fun main() {

     val book1:MyBook = MyBook()

     book1.address = MyAddress("street 23", "Spain")
     book1.address.Show()

     book1.address = MyAddress("street 1", "India")
     book1.address.Show()
}

Example 2 not using lateinit and compilation error

Kotlin

class MyAddress (val street:String, val country:String)
{
     fun Show() { println("${street}, ${country}") }
}

class MyBook
{
     var address: MyAddress build error 'Property must be initialized or be abstract'
}

fun main() {

     val book1:MyBook = MyBook()

     book1.address = MyAddress("street 23", "Spain")
     book1.address.Show()

     book1.address = MyAddress("street 1", "India")
     book1.address.Show()
}

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