Switch widget always returning to off position-CodePudding

I am working on a form where I need to use a switch widget.

Here you have the code for it:

bool isSwitched31 = false;
../
Padding(
                padding: const EdgeInsets.all(8.0),
                child: Row(
                  mainAxisAlignment: MainAxisAlignment.start,
                  children: [
                    Text(
                      'nuevopaciente31'.tr().toString(),
                      style: TextStyle(fontSize: 18),
                    ),
                    Spacer(),
                    Switch(
                      value: isSwitched31,
                      onChanged: (value) {
                        setState(() {
                          isSwitched31 = value;
                          print(isSwitched31);
                        });
                      },
                      activeTrackColor: Colors.lightGreenAccent,
                      activeColor: Colors.green,
                    ),
                  ],
                ),
              ),

When sliding the switch, the print output tells that the swich is on, but it returns always to off position.

What am I doing wrong?

CodePudding user response：

If you declare the variable inside the build method, when the widget is rebuilt 'isSwitched31' will be false again. To fix this you have to declare 'isSwitched31' before the build method