How to read local file in dart?

Question

I created a file user.json in the folder ./assets/.

Then I call:

File file = File('./assets/user.json');
final futureContent = file.readAsString();
futureContent.then((c) => print(c));

But getting exception:

PathNotFoundException (PathNotFoundException: Cannot open file, path = './assets/user.json' (OS Error: No such file or directory, errno = 2))

Absolute path not working as well.

I also tried this way:

  import 'package:path/path.dart' as p;
  void main() {
    var filePath = p.join(Directory.current.path, 'assets', 'user.json');
    File file = File(filePath);
    final futureContent = file.readAsString();
    futureContent.then((c) => print(c));
  }

Still the same error.