Garrett

Garrett

Help, how to update arraylist in jetpack compose

I’m stuck trying to understand how to get a variable initialised, and later updated, in kotlin to update in Jetpack Compose and cause a composition that uses it to recompose. The variable is an arraylist of bitmaps set up like so (all of this works fine so I have not included the getOutputDirectory() and imageReaderNew() functions):

// set up an empty bitmaps arraylist
// should I be using mutableListOf() here? if so how?
var bitmaps: ArrayList<Bitmap> = ArrayList()

// get the uri of the folder to save images to
val outputDirectory = getOutputDirectory()

// read in a list of images in the images folder
var fileList: ArrayList<File> = imageReaderNew(outputDirectory)

// get a list of bitmaps of the images
bitmaps = getBitmapList(fileList)

When I initialise my composition I do this:

BottomSheetScaffold(
scaffoldState = scaffoldState,
sheetPeekHeight = 0.dp,
sheetContent = {
PhotoBottomSheetContent(
bitmaps = bitmaps,
//should I be using remember here?
//bitmaps = remember { bitmaps },
modifier = Modifier.fillMaxWidth()
)
}
)
{ }

Finally, in my composable I do this:

fun PhotoBottomSheetContent(
bitmaps: List<Bitmap>,
// should I be using mutableListOf() or remember { } here? again if so how?
modifier: Modifier = Modifier
)
{
}

Where Next?

Popular Android topics Top

DAZ
Is it possible to develop an application that will generate NFC pulses even when the screen is off?
New
tunelabguy
I have an expensive app ($160) in the Play Store that I would like to update. I would like to do a beta test of the update with potentia...
New
freerefills
I have an android app whereby notifications will fire and immediately leave the tray. This doesn’t always happen, it’s unpredictable they...
New
JesperBlom
Hi Hope it is a simple question :slight_smile: I am planning to use a new PC for making my enterprise app. Everything works perfect, b...
New
Briannamari
Old android photo name sequence Help decoding file names Example. I want to see if a file name aligns with a time / date in which the p...
New
Rodion
Hello everyone, I recently started learning Kotlin and downloaded Android Studio, but after writing my first code and trying to run it, I...
New
sabibo
We recently switched some machines to a network that uses ipV6. Those machines are now unable to package our Unreal game for Android, du...
New
codergrid
I’m new to Android Studio, and curious about how long you’ve been using your Android Studio IDE. I read on Wikipedia that this year, Andr...
New
Garrett
This is a question about Android Studio. Where is the Android Studio emulator’s camera default apartment 3D model stored in Android Stud...
New
Dysentery
I am trying to implement the PIN entry page using device’s TEE. I have acquired the confidential OEM Documentation. It have some C++ code...
New

Other popular topics Top

DevotionGeo
I know that -t flag is used along with -i flag for getting an interactive shell. But I cannot digest what the man page for docker run com...
New
AstonJ
There’s a whole world of custom keycaps out there that I didn’t know existed! Check out all of our Keycaps threads here: https://forum....
New
AstonJ
I’ve been hearing quite a lot of comments relating to the sound of a keyboard, with one of the most desirable of these called ‘thock’, he...
New
AstonJ
Just done a fresh install of macOS Big Sur and on installing Erlang I am getting: asdf install erlang 23.1.2 Configure failed. checking ...
New
AstonJ
If you are experiencing Rails console using 100% CPU on your dev machine, then updating your development and test gems might fix the issu...
New
PragmaticBookshelf
Build highly interactive applications without ever leaving Elixir, the way the experts do. Let LiveView take care of performance, scalabi...
New
Margaret
Hello everyone! This thread is to tell you about what authors from The Pragmatic Bookshelf are writing on Medium.
1143 25816 759
New
rustkas
Intensively researching Erlang books and additional resources on it, I have found that the topic of using Regular Expressions is either c...
New
PragmaticBookshelf
Author Spotlight Jamis Buck @jamis This month, we have the pleasure of spotlighting author Jamis Buck, who has written Mazes for Prog...
New
First poster: bot
Large Language Models like ChatGPT say The Darnedest Things. The Errors They MakeWhy We Need to Document Them, and What We Have Decided ...
New