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Title
# compose
l

Lucca Beurmann

10/20/2021, 8:52 PM
Hello everyone, i'm facing a problem with LazyVerticalGrids that causes my app to crash. I'm using a LazyGrid to display a list of photos (receiving the image url from an api and loading in my view using Glide) that can be cleared whenever the user sends a request with a differente filter, but when the list is cleared my application crashes with an Index out Of Bounds Exception
d

Danish Ansari

10/20/2021, 9:05 PM
You yourself pointed out the actual problem. It doesn't have anything to do 
LazyVerticalGrid
. Wherever you're using your list just put some kind of 
isEmpty()
or 
contains()
check according to your need
l

Lucca Beurmann

10/20/2021, 9:07 PM
I'm already doing this check, only displaying the list if it's not empty
Copy code
if (photos.isEmpty()) {
    SearchPhotosEmpty(Modifier.align(Alignment.Center))
} else {
    SearchPhotosList(
        photos = photos,
        listState = listState,
        onLoadMorePhotos = loadMorePhotos,
        isPreview = isPreview,
        modifier = Modifier.fillMaxSize()
    )
}
c

Chris Miller

10/20/2021, 10:17 PM
Just a guess - is your use of 
photos
threadsafe? And does the LazyGrid know to recompose when the photos change?
l

Lucca Beurmann

10/20/2021, 10:24 PM
I think i found the source of this weird behavior
I'm using a sealed class named ViewState to update my UI according to the proper view state of my screen. This class contains 4 differente types: Idle, Ready, Loading and Error
Copy code
when (screenState) {
    is ViewState.Idle -> {
        Column(
            modifier = Modifier
                .fillMaxSize()
                .padding(horizontal = 20.dp),
            horizontalAlignment = Alignment.CenterHorizontally,
            verticalArrangement = Arrangement.Center
        ) {
            Icon(
                imageVector = Icons.Default.ImageSearch,
                contentDescription = null,
                modifier = Modifier
                    .size(60.dp)
                    .padding()
                    .padding(bottom = 10.dp),
                tint = MaterialTheme.colors.onBackground
            )
            Text(
                text = "Whoops nothing to see here yet, try to search for something cute like fluffy cats.",
                style = AppTypoGraph.roboto_bold().copy(
                    fontSize = 18.sp,
                    textAlign = TextAlign.Center
                )
            )
        }
    }
    is ViewState.Loading -> {
        Box(modifier = Modifier.fillMaxSize(), contentAlignment = Alignment.Center) {
            ProgressIndicator()
        }
    }
    is ViewState.Ready -> Box(Modifier.fillMaxSize()) {
        if (photos.isEmpty()) {
            SearchPhotosEmpty(Modifier.align(Alignment.Center))
        } else {
            SearchPhotosList(
                photos = photos,
                listState = listState,
                onLoadMorePhotos = loadMorePhotos,
                isPreview = isPreview,
                modifier = Modifier.fillMaxSize()
            )
            if (isMorePhotosLoading) MorePhotosLoader(
                modifier = Modifier
                    .align(Alignment.BottomCenter)
                    .padding()
                    .padding(20.dp)
                    .zIndex(1f)
            )
        }

    }
    is ViewState.Error -> Unit
}
I'm using a when statement to set the correct layout and for some reason this is why the exception is occurring
if i extract the LazyGrid of this when clausule and leave it unaware of the current view state it works as intended
I'm just trying to understand why this is happening
well actually this is not the cause of the problem
i was using the .clear() before doing the api call
i moved the clear() to the onSuccess method and it worked
don't know why tho
t

Tobias Suchalla

10/21/2021, 5:39 AM
You're probably seeing this: https://github.com/JetBrains/compose-jb/issues/1157 https://github.com/JetBrains/compose-jb/issues/1173 Build v1.0.0-alpha4-build331 was the last one without this issue.
a

Andrey Kulikov

10/21/2021, 11:58 AM
please file a bug with the stacktrace. it shouldn’t crash
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