How to use a method in a Stateful Widget from another Widget-CodePudding

So i have this toggle() method in the Stateful SideBar class

class SideBar extends StatefulWidget {
  const SideBar({super.key});
  @override
  State<SideBar> createState() => _SideBarState();
}


class _SideBarState extends State<SideBar> with SingleTickerProviderStateMixin{
  void toggle() {
    if (_controller.isCompleted) {
      _controller.reverse();
    }
    else {_controller.forward();}
  }
}

and i want to use it in

class SideBarWidget extends StatelessWidget {
   SideBarWidget({Key? key}) : super(key: key);

  final SideBar sideBarWidget = SideBar(...);

  void toggle() {
    // here i want to use the toggle() method
  }

  @override
  Widget build(BuildContext context) {
    return sideBarWidget;
  }
}

I cannot use sideBarWidget.toggle() I also cannot pass it as a parameter becasue the _controller is in the SideBar() widget

CodePudding user response：

There are many ways, but the most common end simple is to create an instance of the class SideBar like for example: var side = SideBar(); inside the SideBarWidget class And then you can access the toggle() method like side.toggle().

CodePudding user response：

One way is to give the SideBar a GlobalKey and get the state from the key afterwards. An example:

class SideBar extends StatefulWidget {
  const SideBar({super.key});
  @override
  State<SideBar> createState() => SideBarState();
}

class SideBarState extends State<SideBar> with SingleTickerProviderStateMixin{
  @override
  Widget build(BuildContext context) {
    return Container();
  }

  void toggle() {
    print('toggle');
  }
}

class SideBarWidget extends StatelessWidget {
  SideBarWidget({Key? key}) : super(key: key);

  final GlobalKey<SideBarState> sideBarKey = GlobalKey();

  late final SideBar sideBarWidget = SideBar(key: sideBarKey);

  void toggle() {
    sideBarKey.currentState?.toggle();
  }

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        TextButton(onPressed: toggle, child: const Text('click')),
        sideBarWidget,
      ],
    );
  }
}

CodePudding user response：

remove underscore from SideBarState

to use method of SideBarState in SideBarWidget use: SideBarState().toggle();

**screen1.dart**

    class ParentWidget extends StatefulWidget {
              const ParentWidget({Key? key}) : super(key: key);
            
         
    
     @override
          State<ParentWidget> createState() => ParentWidgetState();
        }
        
    class ParentWidgetState extends State<ParentWidget> {
      
      void printData() {
        print("parent");
      }
    
      @override
      Widget build(BuildContext context) {
        return const Placeholder();
      }
    }

**screen2.dart**

    import 'package:demo/screen_1.dart';
    import 'package:flutter/material.dart';
    
    class ChildWidget extends StatelessWidget {
      const ChildWidget({Key? key}) : super(key: key);
    
      @override
      Widget build(BuildContext context) {
        ParentWidgetState().printData();
        return const Placeholder();
      }
    }