How to handle permission requests outside Activity and Fragment?

Question

I'm developing a custom compound View that needs to access external storage. How can I implement the permission handling without involving outside parties, i.e. Activity or Fragment?

I get that I can request the permissions using the View's context, but how can I handle onRequestPermissionsResult() inside the View? Is it even possible?

If it's not possible, what would be the most elegant solution to handle something like this?

Answer 1

You can't work with permissions without the instance of the activity, but you can do your code prettier. If you want to send a request and handle it in one place, then you can use the example below.

Just create something looks like BaseActivity and put there such code

public class PermActivity extends Activity {

    interface OnPermissionCallback{
        void requestResult(String[] permissions, int[] grantResults);
    }

    private SparseArray<OnPermissionCallback> permissionCallback = new SparseArray<>();

    @Override
    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
        permissionCallback.get(requestCode).requestResult(permissions, grantResults);
    }

    public void addPermissionCallback(int requestCode, OnPermissionCallback  callback){
        permissionCallback.put(requestCode, callback);
    }
}

And now in our client code, we can do something like that

class SomeClasThatWorksWithPerms{

    private PermActivity activity;

    public SomeClasWorksWithPerms(PermActivity activity) {
        this.activity = activity;
    }

    void foo(){
        if (ContextCompat.checkSelfPermission(activity, WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED){
            // do something
        }else {
            activity.addPermissionCallback(0, (perms, grantResults) -> {
                if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                    foo(); // try one more
                }
            });
            activity.requestPermissions(new String[]{WRITE_EXTERNAL_STORAGE}, 0);
        }
    }
}

I have used spareArray and indexation by the request code but you can use another way of storing callbacks.

It's very simple example, you can see something more serious there https://github.com/mrizyver/Fl_Launcher/blob/master/app/src/main/java/com/izyver/fllauncher/presentation/activity/FlActivity.kt - as you can see, it is activity https://github.com/mrizyver/Fl_Launcher/blob/master/app/src/main/java/com/izyver/fllauncher/presentation/loaders/WallpaperLoader.kt - our client code that works with permissions