What is the relative performance of a `lateinit va...

# announcements

[Fudge]

What is the relative performance of a `lateinit var`'s isInitialized? Is it just checking some flag, or is it some expensive reflective operation, maybe it allocates objects?

[diesieben07]

It's intrinsified to a simple null check. lateinit var foo: T becomes var foo: T? = null and isInitialized simply checks foo != null

[Fudge]

thanks

[Paul Woitaschek]

For stuff like this just check the bytecode and re-compile it to java if you don't understand bytecode well enough

[Paul Woitaschek]

So if you take this code snippet:

lateinit var variable: String

fun main() {
  val initialized = ::variable.isInitialized
}

[yawkat]

try this site: https://javap.yawk.at/#aCW3vA/procyon

[Paul Woitaschek]

You can just do it in android studio

[Paul Woitaschek]

Find action -> bytecode

[Paul Woitaschek]

public static final void main() {
      boolean initialized = variable != null;
   }

[LeoColman]

I'd like to point out that there are very few cases when you should use this. You would probably rather use a nullable type than not knowing if a variable was initialized

[LeoColman]

Don't make your code go isInitialized everywhere, or you'll return to a Java if not null boilerplate everywhere