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[elye]

https://medium.com/mobile-app-development-publication/simple-kotlin-null-check-for-multiple-mutable-variables-b095f7ac9bf1?source=friends_link&amp;sk=c182bb5d89f7d10985392d8e36f4c228

[muliyul]

People tend to forget about extension functions. What do you think about these alternatives:
fun Any?.isNull() = this == null and
fun Any?.isNotNull() = this != null .

That way you can assert any nullable type in a more readable way (the Kotlin way IMHO)

val a: String? = null
val b: String? = ""

if(a.isNull() && b.isNotNull()) {
 ...
}

You can also add contracts to enable smart casts:

fun Any?.isNull(): Boolean {
 contract {
        returns(true) implies (this == null)
    }
 return this == null
}

*Note: contracts are experimental.