How to make an AnimatedContainer change height after intial widget build, instead of on Button Click

                Expanded(
                  flex: 1,
                  child: Padding(
                    padding: const EdgeInsets.only(bottom: 3.0, right: 1),
                    child: AnimatedContainer(
                      duration: Duration(seconds: 1),
                      height: voteCountList[0],
                      decoration: BoxDecoration(
                        color: ColorChooser.graphColors[int.parse(optionsList[0]['color'])],
                        borderRadius: BorderRadius.all(Radius.circular(2))
                      ),
                    ),
                  ),
                ),

As seen in my code snippet the height of the Animated Container is voteCountList[0], this works fine if the value is updated. However when the widget is initially build there is no animation and the height of the container is instantly = voteCountList[0]. I would like to implement the AnimatedContainer such that the height of the container is seen to animate from 0 to voteCountList[0]. This height needs to animated on build.

If you don't want to use an AnimatedBuilder or create your own Animation controller one way to do it with the Animatedcontainer would be

class MyWidget extends StatelessWidget {
  Future<double> get _height => Future<double>.value(200);

  @override
  Widget build(BuildContext context) {
    return Padding(
        padding: const EdgeInsets.only(bottom: 3.0, right: 1),
        child: FutureBuilder<double>(
          future: _height,
          initialData: 0.0,
          builder: (context, snapshot) {
            return AnimatedContainer(
              duration: Duration(seconds: 1),
              width: 200,
              height: snapshot.data, //voteCountList[0],
              decoration: BoxDecoration(
                color: Colors.red,
                borderRadius: BorderRadius.all(Radius.circular(2))),
            );
        }
      )
    );
  }
}

You start a future with an initial value of 0.0 and after a tick the futures resolve (it's a value you already had, you only transformed it to a future to make him think it will be ready in a tick) and the animation will start from 0 to the resolved future voteCountList[0]