flutter: how to remove icon from expansion panel

Question

in flutter expansion panel, there is a icon on it by default
i want to remove the icon from expansion panel

how i'm gonna do this? here is my code

ExpansionPanelList(
        expansionCallback: (int index, bool isExpanded) {},
        children: [
          ExpansionPanel(

            headerBuilder: (BuildContext context, bool isExpanded) {
              return Stack(children: [
                ListTile(//and the rest of code...

Answer 1

the only way to do it is by editing the ExpansionPanel source code.

I added a new property called hasIcon and set it by default to true (to make sure it will not break the code).

    ExpansionPanel(
      hasIcon: false,       // <------
      canTapOnHeader: true,
      headerBuilder: (BuildContext context, bool isExpanded) {
        return ListTile(
          title: Text(
            'Title',
          ),
        );
      },
      body: Container(),    // <------
      isExpanded: false,    // <------
    ),

and here is how you edit the source code:

Press CTRL + click on ExpansionPanel widget, then search for

this.isExpanded = false,

and add below it

this.isExpanded = false,
this.hasIcon = true,

then search for

final bool isExpanded;

and add below it

final bool isExpanded;
final bool hasIcon;

finally, search for

  Widget header = Row(
    children: <Widget>[
      Expanded(
        child: AnimatedContainer(
          duration: widget.animationDuration,
          curve: Curves.fastOutSlowIn,
          margin: _isChildExpanded(index) ? widget.expandedHeaderPadding : EdgeInsets.zero,
          child: ConstrainedBox(
            constraints: const BoxConstraints(minHeight: _kPanelHeaderCollapsedHeight),
            child: headerWidget,
          ),
        ),
      ),
      expandIconContainer,
    ],
  );

and replace it

  Widget header = Row(
    children: <Widget>[
      Expanded(
        child: AnimatedContainer(
          duration: widget.animationDuration,
          curve: Curves.fastOutSlowIn,
          margin: _isChildExpanded(index) ? widget.expandedHeaderPadding : EdgeInsets.zero,
          child: ConstrainedBox(
            constraints: const BoxConstraints(minHeight: _kPanelHeaderCollapsedHeight),
            child: headerWidget,
          ),
        ),
      ),
      Container(
          child: child.hasIcon? expandIconContainer:null,
      ),
    ],
  );

Answer 2

This works,

Just add SizedBox.shrink() to the trailing properties of ExpansionTile

   ExpansionTile(
              trailing: SizedBox.shrink(),
              title: Text(
                "Title",
                style: TextStyle(
                  fontSize: 18.0,
                  fontWeight: FontWeight.bold
                ),
              ),
              children: <Widget>[
                ExpansionTile(
                  title: Text(
                    'Sub title',
                  ),
                  children: <Widget>[
                    ListTile(
                      title: Text('data'),
                    )
                  ],
                ),
                ListTile(
                  title: Text(
                    'data'
                  ),
                )
              ],
            ),