Why does the image not render in Android Studio when an integer variable containing the drawable is passed to the painterResource function?

Question

I have a requirement to display different images based on certain user interactions. So, I'm storing the drawable resource ID in an integer variable. However, when I pass this variable into the Image's painterResource function the image is not rendered.

Code looks like this:

val img = R.drawable.img1
val img2 = R.drawable.img2

// imageToDisplay is assigned based on certain conditions.
var imageToDisplay = img

Image(painter = painterResource(imageToDisplay), contentDescription = null)

Answer 1

The code you provided is working "as it is" using available drawables in my end, unless you include more details then we can only guess, but when you said

I have a requirement to display different images based on certain user interactions. …

and

… imageToDisplay is assigned based on certain conditions.

and

… when I pass this variable into the Image's painterResource function the image is not rendered.

My best guess is the composable these codes are in is not re-composing or not updating for some reason when you perform some conditional action.

Again, we can only guess so you can try this or just use this as a reference.

@Composable
fun DynamicImageComposable() {

    val img = R.drawable.img
    val img2 = R.drawable.img

    // don't use ordinary variable, convert it to a mutable State instead
    var imageToDisplay by remember {
        mutableStateOf(img) // just use any drawable you want as the initial value
    }

    // when you change this to img2, this composable is expected to re-compose
    imageToDisplay = img

    Image(painter = painterResource(imageToDisplay), contentDescription = null)
}

The logic is a bit useless, but what its trying to point is using mutable state for a composable to re-compose.