JvmNullability.md

Nullability	Java	Kotlin
Not null	Object!	Any
Maybe-nullable	Object	Any!1
Nullable	Object?	Any?
Not null param	T!	T & Any
Nullable param	T?	T?

Operation	Java	Kotlin
Else	original == null ? fallback : original	original ?: fallback
Map if not null	original == null ? null : map(original)	original?.map()
Take if	matches(original) ? original : null	original.takeIf(::matches)
Take unless	matches(original) ? null : original	original.takeUnless(::matches)
Throw if null	original (non-safe usage throws)	original!!

Footnotes

1. Cannot be declared. ↩