I have a nullable Int which can be

null

,

1

,

2

and so on. It's named

condition

. I have a list,

listOf(1,2,3,4)

. That's named

stream

. Based of on

condition

I would like to

filter

for

stream

, but only if it's non-

null

. How can I perform a

filter

operation if a condition either is

null

or a value?

if(condition != null) stream.filter(it == condition) else stream

is one solution I suppose but is there a cleaner way?

IMO your

if

-version is fine. If you want you can create your own little helper function:

inline fun <T> T.runIf(predicate: Boolean, f: (T) -> T) =
    if (predicate)
        f(this)
     else
        this

myList.runIf(condition != null) {
    it.filter(it == condition)
}