Hi, I have a function that does a lengthy operation, but I want it to return only after this operati...

# android

[Remon Shehata]

Hi, I have a function that does a lengthy operation, but I want it to return only after this operation is completed. Also I would like the caller of the function to call it inside a coroutine because it could block them.
I did something like:

suspend fun foo(){
        runBlocking(<http://Dispatchers.IO|Dispatchers.IO>) {
            // do some operation and return only after it's completed
        }
    }

How ever adding the suspend modifier gave me the following warning (posted in reply).

[Remon Shehata]

Screen Shot 2021-09-13 at 2.05.40 PM.png

[Remon Shehata]

not sure how to handle the case I described above; make the function return after it has completed the operation and let the caller use coroutine. thoughts?

[Didier Villevalois]

#coroutines would be a better fit for this question.

runBlocking will block the current thread. Does the operation you do in place of your comment is a thread-blocking operation? If that is the case, I believe what you want to use is withContext(<http://Dispatchers.IO|Dispatchers.IO>) { ... }. In what context do call your foo method?

Also, the Coroutines guide is very helpful.

[Remon Shehata]

if I used

withContext(<http://Dispatchers.IO|Dispatchers.IO>) { ... }

then the function would return immediately. How I want it to return only when the operation is completed.

I call foo from something like :`lifecycleScope.launch(Dispatachers.IO){foo}`

[Remon Shehata]

thanks for your suggestion. I will start asking coroutine related questions in the correct channel

[Rahul Gill]

Look up for Deferred type