Security considerations for Flow in Android?

// Example: Securely managing user permissions in an Android app using Flow
public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Check if the necessary permissions are granted
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE) 
                != PackageManager.PERMISSION_GRANTED) {
            // Request the permission
            ActivityCompat.requestPermissions(this, 
                new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, 1);
        } else {
            // Permission has already been granted, proceed with accessing storage
            accessStorage();
        }
    }

    private void accessStorage() {
        // Code to access external storage
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        if (requestCode == 1) {
            // If request is cancelled, the result arrays are empty.
            if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                // Permission granted, proceed with accessing storage
                accessStorage();
            } else {
                // Permission denied, show a message to the user
                Toast.makeText(this, "Permission denied to access storage", Toast.LENGTH_SHORT).show();
            }
        }
    }
}