Flutter- ExpansionTile expand and collapse on click

Question

I am taking this as a reference to expanding and collapsing of expansion tile-------Flutter - Collapsing ExpansionTile after choosing an item

What I want is if I one

Answer 1

You can use ExpandablePanelList to do perform expand and collapse view. Use expansionCallback to maintain active state to perform expand or collapse. here is the working example

class TestExpandableView extends StatefulWidget {
  @override
  _TestExpandableViewState createState() => _TestExpandableViewState();
}

class _TestExpandableViewState extends State {
  int _activeMeterIndex;
  @override
  Widget build(BuildContext context) {
    return Container(
      child: new ListView.builder(
          itemCount:  2,
          itemBuilder: (BuildContext context, int i) {
            return Card(
              margin:
              const EdgeInsets.fromLTRB(10.0, 15.0, 10.0, 0.0),
              child: new ExpansionPanelList(
                expansionCallback: (int index, bool status) {
                  setState(() {
                    _activeMeterIndex = _activeMeterIndex == i ? null : i;
                  });
                },
                children: [
                  new ExpansionPanel(
                      isExpanded: _activeMeterIndex == i,
                      headerBuilder: (BuildContext context,
                          bool isExpanded) =>
                      new Container(
                          padding:
                          const EdgeInsets.only(left: 15.0),
                          alignment: Alignment.centerLeft,
                          child: new Text(
                            'list-$i',
                          )),
                      body: new Container(child: new Text('content-$i'),),),
                ],
              ),
            );
          }),
    );
  }
}