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what are the two exclamation marks `!!` at the end ^^^ ?

<https://kotlinlang.org/docs/reference/null-safety.html#the--operator>

thanks <@U74HWEPTP>. So not sure why <@UDFFTUW4W> explicitly used `!!` in `return _fulfillmentDetails!!`  ... What would he gain ? And how would it change if he didn't use `!!` ?

That’s a little complicated to answer - in this example, I presume `_fulfillmentDetails` is a a private, nullable type, and the getter that they pasted in exposes a public, non-null type

this is sometimes done as a hacky way to lazily evaluate properties, which is why a lazy delegate is suggested in the thread

but more to the point, because `_fulfillmentDetails` is a nullable `var` and smart-casting cannot safely determine that it contains a non-null value in this instance, you have to tell the compiler to assert that the value is not null, or throw an NPE

an expanded example might look like this :

```class Example {
  private var _fulfillmentDetails: FulfillmentDetails? = null

  public val fulfillmentDetails: FulfillmentDetails
    get() {
      if (_fulfillmentDetails == null) {
        _fulfillmentDetails = FulfillmentDetails(this)  // initialize on first usage
      }
      return _fulfillmentDetails!!  // need to assert/convert to non-nullable type since the declared type is non-nullable
    }
}```


without `!!` this would be a compile error

but there are ways to do this that don’t involve that operator

And in case you are not sure why I could be null even though it was assigned the line before you need to think about multi threaded environments where a different thread could change the value back to null in-between