Is there a better way to pass context to a helper kotlin class?

Question

My application consists of three classes :

• class MainActivity : AppCompatActivity()
• class Map : Fragment() , OnMapReadyCallback
• class DataWriter(val context: Context): AppCompatActivity()

Map contains google map methods and DataWriter contains File writer methods as long with a write storage permission check on runtime IsWriteEnabled().

I call IsWriteEnabled() from Map so I can check If I have permissions with the following way:

class Map : Fragment() , OnMapReadyCallback {

    private lateinit var mdataWriter: DataWriter

// a lot of code removed

 override fun onMapReady(googleMap: GoogleMap) {
        mdataWriter = DataWriter(requireContext())
        mdataWriter.isWriteEnable()
    }

here is my DataWriter.kt

class DataWriter(val context: Context): AppCompatActivity(){

    fun isWriteEnable(): Boolean { 
        if (ActivityCompat.checkSelfPermission(
                context,   
                Manifest.permission.WRITE_EXTERNAL_STORAGE
            ) != PackageManager.PERMISSION_GRANTED
        ) {
            ActivityCompat.requestPermissions(
                context as Activity,
                arrayOf(
                    Manifest.permission.WRITE_EXTERNAL_STORAGE
                ),
                WRITE_REQUEST_CODE
            )
        } else {
            Log.e("DB", "PERMISSION GRANTED")
        }
        return true
    }

My question

Is there a better way to pass context to a class that its not attached to main activity? Is the call to the method as it should be?

Answer 1

You are free to pass a Context to a class that its not attached to an Activity in any way you like. Passing it through the class's constructor is a good practice (dependency injection), but only in the case where your class needs a Context to fully function correctly. If you need a Context to use only in a specific method, might as well pass it as an argument to the method.

The most important thing you have to be aware here is that an Activity has a finite life cycle. If you keep a reference to an Activity Context in a class that will outlive that Activity, you will create a memory leak: the garbage collector will not be able to destroy that Activity because there's a reference to it somewhere. This is why people usually prefer to handle an Application Context instead, which will always outlive any class you can create.

Now, a correction to your code: don't extend AppCompatActivity just to inherit ActivityCompat. By extending AppCompatActivity, you're granting the class access to a lot of life cycle management, resource handling and user interaction methods that have nothing to do with your class. AppCompatActivity is supposed to be extended by Activities only. Otherwise, its name would not end with Activity :)

As components that handle user interaction, asking for permissions is a responsibility of the Activity or Fragment, so just ask for the permission either in Map or MainActivity. Also, I'm assuming that Map is indeed doing what a Fragment is supposed to do, and you're not just extending Fragment to get access to some Fragment methods :)