Let me offer this conceptual model: `launch` is ju...

# coroutines

[elizarov]

Let me offer this conceptual model: launch is just like starting a new thread. If the code inside launch crashes with exception then it is considered “uncaught” exception and, generally, should crash your app (on Android that happens automatically). However, when you use async and the execution results with exception, then this exception gets stored inside the Deferred. It is your obligation to process it later. So:
- launch - fire and forget, crash application on uncaught error;
- async - launch and await for result later. You must await on a coroutine that you’ve created with async. You MUST NOT forget about the coroutine you’ve started with async.

[deviant]

or we can catch exception in invokeOnCompletion() after launch is finished. or it's not recommended?

[elizarov]

You cannot “catch” it with invokeOnCompletion. You can only get notified on it.

[elizarov]

If you want to prevent crash due to uncaught exception, you should install CoroutineExceptionHandler in your context.

[deviant]

do you have some examples? din't find it in the doc

[elizarov]

No samples. That is all we have now: https://kotlin.github.io/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines.experimental/-coroutine-exception-handler/index.html

[deviant]

so we use it like launch(UI+myExHandler)?

[elizarov]

yes

[deviant]

thanks! i'll try it

[elizarov]

Added that to stackoverflow: https://stackoverflow.com/questions/46226518/what-is-the-difference-between-launch-join-and-async-await-in-kotlin-coroutines/46226519#46226519