my company needs a future type (on Java 7, so no

CompletableFuture<T>

. But we have mixed kotlin/java code. Does that mean we cannot use

Deffered<T>

?

The most important method of

Deferred<T>

is

await()

, which is

suspend

function. As you may know, you can't invoke such functions from Java code. So I believe your best bet is to use

kotlinx-coroutines-guava

module which binds Guava's

ListenableFuture

(available for Java 7) and coroutines(https://github.com/Kotlin/kotlinx.coroutines/tree/master/integration/kotlinx-coroutines-guava). If the size of the Guava is a concern and it's not used in the project otherwise, it might be an option to pull in

streamsupport

library (https://github.com/streamsupport/streamsupport) -- it has backport of

CompletableFuture<T>

for previous Java versions. You'll have to provide coroutine wrappers yourself though, because package name is different, so

kotlinx-coroutines-jdk8

won't work as is. You might be able to just repackage jar changing package name.