# Android Compose, how to 'Observe' ScalingLazyColumn

**URL:** <https://discuss.kotlinlang.org/t/android-compose-how-to-observe-scalinglazycolumn/29491>\
**Category:** Uncategorized\
**Created:** [November 7, 2024, 1:11pm UTC](https://discuss.kotlinlang.org/t/android-compose-how-to-observe-scalinglazycolumn/29491 "2024-11-07T13:11:30Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![richp999999](https://avatars.discourse-cdn.com/v4/letter/r/91b2a8/32.png) [@richp999999](https://discuss.kotlinlang.org/u/richp999999)\
**Post date:** [November 7, 2024, 1:11pm UTC](https://discuss.kotlinlang.org/t/android-compose-how-to-observe-scalinglazycolumn/29491/1 "2024-11-07T13:11:30Z")

</div>

Hi,

New to Kotlin/Android/Compose dev, trying to get my head around state changes.

I have a ScalingLazyColumn , and hold the state like this:

val listState = rememberScalingLazyListState(  
initialCenterItemIndex = 0  
)

How do I wire up an Event that will fire when listState.centerItemIndex changes ?

I’ve read lots but can’t seem to work it out.

I believe it may need to be ‘observed’, in order for it to re-compose ?

I’m looking for something like an ‘onChange()’ event or similar ?

My ScalingLazyList contains a list of items, and I want an item to change when it becomes the ‘centerItemIndex’.  
How do I achieve this ?

Does the item have to ‘listen’ to changes on listState ?

Thanks,  
Richard.