after ```private var factory: DBConnectionFactory? = null ...``` what is better the best way to avoi...

# codereview

[christophsturm]

after

private var factory: DBConnectionFactory? = null
...

what is better the best way to avoid the !! here?

if (factory != null)
   return factory!!.getConnection()

factory?.getConnection()?.also { return it }

works, but looks obfuscated to me.

[Paul Griffith]

you can do factory?.let { it.getConnection() } but I prefer plain if null checks most of the time, even if I have to “pay” the cost of an extra variable

[christophsturm]

factory?.let { return it.getConnection() }

is way better than my version 2, what was I thinking…

[christophsturm]

thanks, but you are right, i will also keep the if.

[alex.krupa]

These 2 aren't the same. In the if variant factory can change between the null-check and the unsafe access, so there's risk of a NullPointerException being thrown (e.g. when it's modified from different threads).

You can avoid it by assigning the reference locally:

val factory = factory
if (factory != null) {
    return factory.getConnection() // factory will be non-null here
}

[Zun]

Or consider rewriting your code so that your factory can not be null

[christophsturm]

this is just a lazy variable, it is null at the beginning and then it is set. but it can’t use lazy {} because the method is suspend

[Riccardo Lippolis]

if you know that the variable will not be accessed until it is lazily initialized, you could make it a lateinit var? Then it doesn't need to be nullable anymore