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I'm trying to create an app (using Kotlin with Jetpack Compose) that can save files to internal storage, but I don't know what is the best place to put for example this code:

fun deleteFile(context: Context, filePath: String): Boolean {
    
    val path = context.filesDir
    val file = File(path, filePath)

    if (!file.exists()) return false
    
    return file.deleteRecursively()
}

Since I need the context to handling files the code must be in the UI layer right? But isn't it a business code? If is business code I can't put it in the data layer because I need context, passing the context to the viewModel is also not good, so where?

Matteo Zattera
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1 Answers1

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Typically, in an Android app architecture that follows the recommended practices, you would have separate layers such as UI layer (composed of activities/fragments and Jetpack Compose), ViewModel layer, and Data layer (including repositories and data sources). To handle file operations, you can introduce a repository pattern.

The FileRepository class acts as an intermediary between the ViewModel and the file system, utilizing the application context to delete files from internal storage.

class FileRepository(private val application: Application) {

    fun deleteFile(filePath: String): Boolean {
        val path = application.filesDir
        val file = File(path, filePath)

        if (!file.exists()) return false

        return file.deleteRecursively()
    }
}

The MyViewModel class extends AndroidViewModel and holds an instance of the FileRepository. It serves as a bridge between the UI layer and the file handling logic,

class MyViewModel(application: Application) : AndroidViewModel(application) {

    private val fileRepository by lazy { FileRepository(application) }
    
    fun deleteFile(filePath: String): Boolean {
        return fileRepository.deleteFile(filePath)
    }
}

Example usage

@Composable
fun Example(myViewModel: MyViewModel = viewModel()) {
    // UI
}

The function takes an instance of MyViewModel as a parameter, with a default value obtained using the viewModel() function. Inside the function, you would define the UI elements and layout specific to this component.

Sri mani789
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  • So if I understood correctly, I was using the **activity context** which is not suitable because passing it to the viewModel can cause memory leaks due to the fact that the activity live shorter than viewModel, but with the **application context** there's no such problem, right? – Matteo Zattera Jul 08 '23 at 09:12
  • yes, and here is a good explanation about AndroidViewModel https://stackoverflow.com/q/44148966/17664120 – Sri mani789 Jul 08 '23 at 11:25