What’s the best practice to keep all the constants in Flutter? [closed]

My preferred solution is to make my own Dart library.

Make a new dart file named constants.dart, and add the following code:

const String SUCCESS_MESSAGE=" You will be contacted by us very soon.";

Edit: 99% of the time you don’t need to explicitly name your dart libraries with a statement like library library_name; at the top of your file, and you probably shouldn’t (reference).
Even if you leave out this line your file will still be library! It will just be implicitly named.

Then add the following import statement to the top of any dart file which needs access to the constants:

import 'constants.dart' as Constants;

Note if constants.dart is in different directory then you will need to specify the path to constants.dart in your import statement.

EDIT: Use lowercase_with_underscores when specifying a library prefix.

In this example:

You could use a relative path:

import '../assets/constants.dart' as constants;

Or an absolute path from the lib directory:

import 'package:<your_app_name>/assets/constants.dart' as constants;

Now you can easily access your constants with this syntax:

String a = Constants.SUCCESS_MESSAGE;