At first glance, MutableState and MutableStateFlow work equally well in Composable. What is better t...

# compose-desktop

[Vadim Kapustin]

At first glance, MutableState and MutableStateFlow work equally well in Composable. What is better to use?

[Animesh Sahu]

In my observations/opinion, the Compose compiler plugin generates some stubs to redraws only things whose state have been changed. You can always collect a state flow with a .collectAsState() to get state representation of the StateFlow.

As far as I understood, every event fires redraw event of all the children UI elements, but only whose state changed actually gets executed and changed. When using a StateFlow, and directly calling StateFlow.value you'll be redrawing the UI for every single event like mouse move, mouse enter, mouse click, to the element you are using it with, even if the value wasn't changed.

[Animesh Sahu]

I'm not so sure about this, but I think I'm correct according to use-case I've observed here:

https://www.youtube.com/watch?v=DDd6IOlH3io?t=5m56s▾

(timestamp: 5min 56sec)

[Vadim Kapustin]

I don't seem to understand their mechanisms. I made an experiment to check the repetition of redrawing when the value did not change and got no redrawing at all even when the value changed... I'll look at this in more detail

[Vadim Kapustin]

Thanks for reply 🙂

[gildor]

Have you checkedJetpack Compse doc?
Path way is very good starting point
https://developer.android.com/courses/pathways/compose

[gildor]

Your right, they are similat, observable state holder, but with own api and different use case

[Zach Klippenstein (he/him) [MOD]]

I would reach for Flow-based tools first, since they rely on less magic and are easier to test with, imo. It also keeps the non-compose bits of your code compose-free, which can make it easier to refactor modules later on.

[Shawn Witte]

For everything outside of a @Compose function, I use Flow (or whichever subclass is appropriate, e.g. StateFlow), because Flow is fairly universal. However, the first few lines of my @Compose functions all convert those to State via collectAsState() because I know the composables will properly handle updates to State.