CODEWITHSUNDEEP
androidkotlinandroid-jetpack-compose
Hrishikesh Kokate
Hrishikesh Kokate

Reputation: 1225

Adding a custom class breaks Compose compilation

I'm just trying to get started with Android development and Kotlin using Jetpack Compose. Note that, I'm a Kotlin novice, so I'm trying to learn along the way. I come from JavaScript/TypeScript background, so I'm trying to learn by thinking in JavaScript terms and implement in Kotlin terms by searching online.

I'm trying to list all installed applications on the device. While the app was working as expected up till now, I needed to add a feature to sort the installed app names. I referred to: https://www.bezkoder.com/kotlin-sort-list-objects/#Create_Class_for_handling_sorting. As soon as I added a custom class to sort the List<ApplicationInfo>, my app stopped building.

I have included my repo here: https://github.com/Hrishikesh-K/TryKotlin

If I comment these lines and this line as well, the app builds fine. With the current setup, I get an error:

Functions which invoke @Composable functions must be marked with the @Composable annotation

which points to line 21, character 18, which is the start of the word compare.

I don't understand why Compose would care about a custom class, it's not a Composable function after all. What am I missing?

Upvotes: 0

Views: 92

Answers (1)

Gabriele Mariotti
Gabriele Mariotti

Reputation: 364556

In the compare method you are using LocalContext.current

override fun compare(o1 : ApplicationInfo, o2 : ApplicationInfo): Int {
    return o1.loadLabel(LocalContext.current.packageManager).toString().compareTo(o2.loadLabel(LocalContext.current.packageManager).toString())
}

You can't use a @Composable functions if the method is not marked with the @Composable.

Use something different like:

data class CompareApplicationNames(val context: Context) : Comparator<ApplicationInfo> {

    override fun compare(o1 : ApplicationInfo, o2 : ApplicationInfo): Int {
        return o1.loadLabel(context.packageManager).toString().compareTo(o2.loadLabel(context.packageManager).toString())
    }
}

Then just use:

Log.d("sorted:", listOfApplications.sortedWith(CompareApplicationNames(LocalContext.current)).toString())

Upvotes: 1

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