如何在 statelessWidget 中使用 setState() 函数 class

Question

我无法在 dialogContent 中使用 setState 函数，我得到了这个错误：

The method 'setState' isn't defined for the class 'CustomDialog'

这里我用了setState()

Row(
                  mainAxisAlignment: MainAxisAlignment.center,
                  crossAxisAlignment: CrossAxisAlignment.center,
                  children: status ? <Widget>[
                    Container(
                      child: Padding(
                        padding: EdgeInsets.only(right: 5,top: 0),
                        child: Image.asset(
                          'assets/images/profile.png',
                          width: 60.0,
                          height: 60.0,
                        ),
                      ),
                    ),
                    Padding(
                        padding: const EdgeInsets.only(top: 0.0),
                        child: Container(
                          width: 200.0,
                          decoration: BoxDecoration(
                            color: Colors.white,
                            borderRadius: BorderRadius.only(
                              topLeft: const Radius.circular(50.0),
                              topRight: const Radius.circular(50.0),
                              bottomLeft: const Radius.circular(50.0),
                              bottomRight: const Radius.circular(50.0),
                            ),
                          ),
                          child: Padding(
                            padding: const EdgeInsets.all(20.0),
                            child: Center(
                              child: Text(
                                'test',
                                style: TextStyle(
                                    color: Colors.black,
                                    fontWeight: FontWeight.bold,
                                    fontSize: 25.0
                                ),
                              ),
                            ),
                          ),
                        )
                    ),
                    Padding(
                      padding: const EdgeInsets.only(left: 5.0),
                      child: CustomSwitch(
                        activeColor: Colors.green,
                        value: status,
                        onChanged: (value) {
                          print("VALUE : $value");
                          setState(() {
                            status = value;
                          });
                        },
                      ),
                    ),
                  ] :
                  [
                    Expanded(
                      child: Padding(
                        padding: const EdgeInsets.only(left :25.0),
                        child: Center(
                          child: Text(
                            'test',
                            style: TextStyle(
                              color: Colors.red,
                              fontSize: 15.0,
                            ),
                          ),
                        ),
                      ),
                    ),
                    Padding(
                      padding: const EdgeInsets.only(left: 0.0),
                      child: CustomSwitch(
                        activeColor: Colors.green,
                        value: status,
                        onChanged: (value) {
                          print("VALUE : $value");
                          setState(() {
                            status = value;
                          });
                        },
                      ),
                    ),
                  ]
              ),

Answer 1

当然不能在StatelessWidget 中使用setState()，这就是这个widget 的想法。 StatelessWidget 应该只用于不应保持任何状态的“哑”视图。 如果您应该为小部件设置任何状态，请考虑使用 StatefulWidget。

查看 flutter 官方文档： https://api.flutter.dev/flutter/widgets/StatelessWidget-class.html