从常规 java function 向 kotlin 的流发送数据

Question

I have an external interface which I cannot change:

interface ExternalApi {
    fun onDataReceived(data: String)
}

I need to start consuming data and send it to flow . Data order is a necessity. I'd like to have a cold flow , but I couldn't find a version of cold flow with emit function, so I used hot flow + replay set to Max value as a workaround. Here was my first try:

class FlowProblem {
    val flow: MutableSharedFlow<String> = MutableSharedFlow(replay = Int.MAX_VALUE)

    fun startConsuming() {
        object : ExternalApi {
            override fun onDataReceived(data: String) {
                flow.emit(data)
            }
        }
    }
}

Unfortunately it doesn't work as emit function is a suspended function. However this is an external interface and I cannot add suspend modifier. I tried to also do something like this:

override fun onDataReceived(data: String) {
    val coroutineScope = CoroutineScope(Job())
    coroutineScope.launch {
        flow.emit(data)
    }
}

but for me it's kind a silly to create new coroutine only in order to move data to flow. I'm also wondering about data order.

What should I do? Maybe flow/channel is not suitable here and I should pick something another?

Answer 1

Thanks IR42, callbackFlow was exactly what I needed.