AnimatedWidget and AnimatedBuilder in Flutter

Question

Hi everyone ，I have a problem, I don’t understand the difference between AnimatedWidget and AnimatedBuilder. The comments in the source code are as follows:

AnimatedWidget:

/// For more complex case involving additional state, consider using
/// [AnimatedBuilder].

AnimatedBuilder:

/// For simple cases without additional state, consider using
/// [AnimatedWidget].

I want to know how to choose between them, because I don't quite understand the documentation, thanks!

Answer 1

There's no real difference between them besides the syntax needed to use it.

To be clear, this is the code of AnimatedBuilder :

class AnimatedBuilder extends AnimatedWidget {
  const AnimatedBuilder({
    Key key,
    @required Listenable animation,
    @required this.builder,
    this.child,
  }) : assert(builder != null),
      super(key: key, listenable: animation);

  final TransitionBuilder builder;
  final Widget child;

  @override
  Widget build(BuildContext context) {
    return builder(context, child);
  }
}

...Yup, does nothing

From this code we can clearly see that AnimatedBuilder is just a different syntax of using AnimatedWidget. Since AnimatedBuilder is an AnimatedWidget that delegate all the layout logic to a callback

So in the end, it's really up to you. Both do the same thing. Use what makes it more readable for you