Hi, i'm making a class that check audio input leve...

# coroutines

[Jérôme Gully]

Hi, i'm making a class that check audio input level in Android, for do that I must call one method each 100ms in a separate thread and notify the value with a lambda block, for the moment I have this (old school hava style) and I guess I can do better with coroutines.
mustStopThread is a boolean that is false when class is created and true when I must stop the check (when I quit the activity). What I can do better ?

init {
    Thread(Runnable {
        while (!mustStopThread) {
            val lastMaxSoundLevel: Int = mediaRecorder.maxAmplitude
            block.invoke(lastMaxSoundLevel)
            Thread.sleep(100)
        }
    }).start()
}

[elizarov]

First, replace mustStopThread with a scope:

val myScope = CoroutineScope(Dispatchers.Default)

Then, you can replace your code with:

init { 
    myScope.launch { 
        while (isActive) {
             ... // as before
             delay(100) // instead of Thread.sleep
        }
    }
}

When you need to stop, you’d call myScope.cancel()

[Jérôme Gully]

Thanks for the answer ! isActive is very useful 🙂

[elizarov]

In this particular case you don’t have to do while (isActive) and while (true) would work just as well, becuase delay checks for it. But the code just looks better and more understandable this way, highlighting the fact that you are looping not forever, but until cancellation.

[Jérôme Gully]

Agree, code is more declarative with while(isActive) 👌