Hi guys, i have this function inside my kotlin shared library. ```suspend fun fetchUsers(): List<...

# multiplatform

[Joey]

Hi guys, i have this function inside my kotlin shared library.

suspend fun fetchUsers(): List<String> {
        val response = client.get<JsonObject> { url("$baseUrl/heartbeat.json") }
        val userIds = response.keys.toList()
        return userIds
    }

Now im trying to implement it in a pure old java project. I enabled the kotlin plugin in this project and created this function:

fun fetchUsersFromKtLib(): List<String> {
    val api = HeartbeatApi()
    val users = GlobalScope.future { api.fetchUsers()  }
    return users.get()
}

Now everytime im calling this fetchUsersFromKtLib function, there is a jank in my UI (a freeze). Im trying to solve this problem for about 3 days now. So far this is the cleanest way i called the function from the kotlin shared library. What can you suggest to avoid any UI freeze? Thanks guys!

[Joey]

Im starting to think of removing the fetching of data in my kotlin library. I will just create a function that returns the api endpoint and do the fetching in java.

Which is the better approach?

[yshrsmz]

it's because your second function is synchronous

[yshrsmz]

fun fetchUsersFromKtLib(callback: (users:List<String>) -> Unit) {
    val api = HeartbeatApi()
    GlobalScope.launch { 
        val users = api.fetchUsers()
        callback(users)
    }
}

you need to convert to callback or return as CompletableFuture and consume it asynchronously

[Joey]

Got it working! Thank you very much!

[Joey]

Anyone that deals with the same use case. This is the final code:
Kotlin shared lib

fun fetchUsersFromKtLib(callback: (String) -> Unit) {
        GlobalScope.launch {
            val response = client.get<JsonObject> { url("$baseUrl/heartbeat.json") }
            val listOfUsers = response.keys.iterator()
            listOfUsers.forEach {
                callback(it)
            }
        }
    }

Kotlin class inside old java project

fun fetchUsers(listFromAndroid: ArrayList<String>) {
    val api = HeartbeatApi()
    return api.fetchUsersFromKtLib {
        listFromAndroid.add(it)
    }
}

Big thanks to @yshrsmz

[marstran]

You could also just return the future:

fun fetchUsersFromKtLib(): CompletableFuture<List<String>> {
    val api = HeartbeatApi()
    return GlobalScope.future {
      api.fetchUsers()  
    }
}

[Joey]

Where should i use this? In my android project? Cant seem to find CompletableFuture

@marstran

[marstran]

Hmm, doesn’t GlobalScope.future return a CompletableFuture ?

[Joey]

Nevermind found the correct plugin. My api.fetchUsers() should return the list of string right?

[marstran]

Yes

[Joey]

Will try this and get back to you 😄