How to check if a “lateinit” variable has been initialized?

Question

I wonder if there is a way to check if a lateinit variable has been initialized. For example:

class Foo() {

    private lateinit var myFile: Fi         


        

Answer 1

If you have a late init property in one class and need to check if it is initialized from another class

if(foo::file.isInitialized) // this wouldn't work

The workaround I have found is to create a function to check if the property is initialized and then you can call that function from any other class.

Example:

class Foo() {

    private lateinit var myFile: File

    fun isFileInitialised() = ::file.isInitialized
}

 // in another class
class Bar() {

    val foo = Foo()

    if(foo.isFileInitialised()) // this should work
}

Answer 2

There is a lateinit improvement in Kotlin 1.2 that allows to check the initialization state of lateinit variable directly:

lateinit var file: File    

if (this::file.isInitialized) { ... }

See the annoucement on JetBrains blog or the KEEP proposal.

UPDATE: Kotlin 1.2 has been released. You can find lateinit enhancements here:

• Checking whether a lateinit var is initialized
• Lateinit top-level properties and local variables