Flutter 无法在Flatter中将变量值从一个无状态小部件传递到另一个无状态小部件_Flutter

Flutter 无法在Flatter中将变量值从一个无状态小部件传递到另一个无状态小部件

flutter

Flutter 无法在Flatter中将变量值从一个无状态小部件传递到另一个无状态小部件,flutter,Flutter,谢谢你前面的回答。我试图将“用户名、电子邮件、密码”从GetTextField无状态小部件中的TextField小部件传递到GetSignup无状态小部件中的GestureDetector小部件中的print函数。我尝试了两种方法，但在填充字段并按下按钮后，都会显示“用户名：null、用户电子邮件：null、用户密码：null”消息。可能有什么问题方法1: class SignupScreen extends StatefulWidget { static const id = "sign

谢谢你前面的回答。我试图将“用户名、电子邮件、密码”从GetTextField无状态小部件中的TextField小部件传递到GetSignup无状态小部件中的GestureDetector小部件中的print函数。我尝试了两种方法，但在填充字段并按下按钮后，都会显示“用户名：null、用户电子邮件：null、用户密码：null”消息。可能有什么问题

方法1:

class SignupScreen extends StatefulWidget {
  static const id = "signup_screen";
  @override
  _SignupScreenState createState() => _SignupScreenState();
}

class _SignupScreenState extends State<SignupScreen> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: CustomPaint(
        painter: BackgroundSignup(),
        child: Stack(
          children: <Widget>[
            Padding(
              padding: EdgeInsets.symmetric(
                horizontal: 35,
              ),
              child: Column(
                children: <Widget>[
                  GetHeader(),
                  GetTextField(),
                  GetSignup(),
                  GetButtonRow(),
                ],
              ),
            ),
            GetBackButton(),
          ],
        ),
      ),
    );
  }
}

class GetTextField extends StatelessWidget {
  String email;
  String password;
  String username;
  @override
  Widget build(BuildContext context) {
    return Expanded(
      flex: 4,
      child: Column(
        mainAxisAlignment: MainAxisAlignment.end,
        children: <Widget>[
          SizedBox(
            height: 15,
          ),
          Directionality(
            textDirection: TextDirection.rtl,
            child: TextField(
              onChanged: (value) {
                username = value;
              },
              textAlign: TextAlign.start,
              decoration: InputDecoration(
                labelText: "الاسم كاملا",
                labelStyle:
                    TextStyle(color: Colors.white, fontWeight: FontWeight.bold),
                enabledBorder: UnderlineInputBorder(
                  borderSide: BorderSide(color: Colors.white),
                ),
              ),
            ),
          ),
          SizedBox(
            height: 15,
          ),
          Directionality(
            textDirection: TextDirection.rtl,
            child: TextField(
              onChanged: (value) {
                email = value;
              },
              textAlign: TextAlign.start,
              decoration: InputDecoration(
                labelText: "الإيميل",
                labelStyle:
                    TextStyle(color: Colors.white, fontWeight: FontWeight.bold),
                enabledBorder: UnderlineInputBorder(
                  borderSide: BorderSide(color: Colors.white),
                ),
              ),
            ),
          ),
          SizedBox(
            height: 15,
          ),
          Directionality(
            textDirection: TextDirection.rtl,
            child: TextField(
              onChanged: (value) {
                password = value;
              },
              obscureText: true,
              textAlign: TextAlign.start,
              decoration: InputDecoration(
                labelText: "كلمة السر",
                labelStyle:
                    TextStyle(color: Colors.white, fontWeight: FontWeight.bold),
                enabledBorder: UnderlineInputBorder(
                  borderSide: BorderSide(color: Colors.white),
                ),
              ),
            ),
          ),
          SizedBox(
            height: 25,
          ),
        ],
      ),
    );
  }
}

class GetSignup extends StatelessWidget {
  GetTextField getTextField = GetTextField();

  @override
  Widget build(BuildContext context) {
    return Expanded(
      flex: 1,
      child: Row(
        mainAxisAlignment: MainAxisAlignment.spaceBetween,
        children: <Widget>[
          GestureDetector(
            onTap: () {
              print('user name: ${getTextField.username}');
              print('user email: {getTextField.email}');
              print('user password: ${getTextField.password}');
            },
            child: CircleAvatar(
              backgroundColor: Colors.grey.shade800,
              radius: 40,
              child: Icon(
                Icons.arrow_back,
                color: Colors.white,
              ),
            ),
          ),
          Text(
            "انشئ حسابك",
            style: TextStyle(
              fontSize: 25,
              fontWeight: FontWeight.bold,
            ),
          ),
        ],
      ),
    );
  }
}

class SignupScreen extends StatefulWidget {
  static const id = "signup_screen";
  @override
  _SignupScreenState createState() => _SignupScreenState();
}

class _SignupScreenState extends State<SignupScreen> {
  GetTextField getTextField = GetTextField();
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: CustomPaint(
        painter: BackgroundSignup(),
        child: Stack(
          children: <Widget>[
            Padding(
              padding: EdgeInsets.symmetric(
                horizontal: 35,
              ),
              child: Column(
                children: <Widget>[
                  GetHeader(),
                  GetTextField(),
                  GetSignup(
                    username: getTextField.username,
                    email: getTextField.email,
                    password: getTextField.password,
                  ),
                  GetButtonRow(),
                ],
              ),
            ),
            GetBackButton(),
          ],
        ),
      ),
    );
  }
}

class GetTextField extends StatelessWidget {
  String email;
  String password;
  String username;
  @override
  Widget build(BuildContext context) {
    return Expanded(
      flex: 4,
      child: Column(
        mainAxisAlignment: MainAxisAlignment.end,
        children: <Widget>[
          SizedBox(
            height: 15,
          ),
          Directionality(
            textDirection: TextDirection.rtl,
            child: TextField(
              onChanged: (value) {
                username = value;
              },
              textAlign: TextAlign.start,
              decoration: InputDecoration(
                labelText: "الاسم كاملا",
                labelStyle:
                    TextStyle(color: Colors.white, fontWeight: FontWeight.bold),
                enabledBorder: UnderlineInputBorder(
                  borderSide: BorderSide(color: Colors.white),
                ),
              ),
            ),
          ),
          SizedBox(
            height: 15,
          ),
          Directionality(
            textDirection: TextDirection.rtl,
            child: TextField(
              onChanged: (value) {
                email = value;
              },
              textAlign: TextAlign.start,
              decoration: InputDecoration(
                labelText: "الإيميل",
                labelStyle:
                    TextStyle(color: Colors.white, fontWeight: FontWeight.bold),
                enabledBorder: UnderlineInputBorder(
                  borderSide: BorderSide(color: Colors.white),
                ),
              ),
            ),
          ),
          SizedBox(
            height: 15,
          ),
          Directionality(
            textDirection: TextDirection.rtl,
            child: TextField(
              onChanged: (value) {
                password = value;
              },
              obscureText: true,
              textAlign: TextAlign.start,
              decoration: InputDecoration(
                labelText: "كلمة السر",
                labelStyle:
                    TextStyle(color: Colors.white, fontWeight: FontWeight.bold),
                enabledBorder: UnderlineInputBorder(
                  borderSide: BorderSide(color: Colors.white),
                ),
              ),
            ),
          ),
          SizedBox(
            height: 25,
          ),
        ],
      ),
    );
  }
}

class GetSignup extends StatelessWidget {
  final username;
  final email;
  final password;
  GetSignup({this.username, this.email, this.password});
  @override
  Widget build(BuildContext context) {
    return Expanded(
      flex: 1,
      child: Row(
        mainAxisAlignment: MainAxisAlignment.spaceBetween,
        children: <Widget>[
          GestureDetector(
            onTap: () {
              print('user name: $username');
              print('user email: $email');
              print('user password: $password');
            },
            child: CircleAvatar(
              backgroundColor: Colors.grey.shade800,
              radius: 40,
              child: Icon(
                Icons.arrow_back,
                color: Colors.white,
              ),
            ),
          ),
          Text(
            "انشئ حسابك",
            style: TextStyle(
              fontSize: 25,
              fontWeight: FontWeight.bold,
            ),
          ),
        ],
      ),
    );
  }
}

class SignupScreen扩展StatefulWidget{
静态常量id=“注册屏幕”；
@凌驾
_SignupScreenState createState（）=>\u SignupScreenState（）；
}
类_SignupScreenState扩展状态{
@凌驾
小部件构建（构建上下文）{
返回脚手架(
车身：定制喷漆(
画家：背景签名（），
子：堆栈(
儿童：[
填充物(
填充：EdgeInsets.symmetric(
横向：35，
),
子：列(
儿童：[
GetHeader（），
GetTextField（），
GetSignup（），
GetButtonRow（），
],
),
),
GetBackButton（），
],
),
),
);
}
}
类GetTextField扩展了无状态小部件{
字符串电子邮件；
字符串密码；
字符串用户名；
@凌驾
小部件构建（构建上下文）{
扩大回报(
弹性：4，
子：列(
mainAxisAlignment:mainAxisAlignment.end，
儿童：[
大小盒子(
身高：15，
),
方向性(
textDirection:textDirection.rtl，
孩子：TextField(
一旦更改：（值）{
用户名=值；
},
textAlign:textAlign.start，
装饰：输入装饰(
标签文字：“ااااكالا”，
标签样式：
TextStyle（颜色：Colors.white，fontwweight:fontwweight.bold），
enabledBorder:UnderlineInputBorder(
borderSide:borderSide（颜色：Colors.white），
),
),
),
),
大小盒子(
身高：15，
),
方向性(
textDirection:textDirection.rtl，
孩子：TextField(
一旦更改：（值）{
电子邮件=价值；
},
textAlign:textAlign.start，
装饰：输入装饰(
标签文字：“الإيمل”，
标签样式：
TextStyle（颜色：Colors.white，fontwweight:fontwweight.bold），
enabledBorder:UnderlineInputBorder(
borderSide:borderSide（颜色：Colors.white），
),
),
),
),
大小盒子(
身高：15，
),
方向性(
textDirection:textDirection.rtl，
孩子：TextField(
一旦更改：（值）{
密码=值；
},
蒙昧文字：对，
textAlign:textAlign.start，
装饰：输入装饰(
标签文字：“كلمة㶟لسس”，
标签样式：
TextStyle（颜色：Colors.white，fontwweight:fontwweight.bold），
enabledBorder:UnderlineInputBorder(
borderSide:borderSide（颜色：Colors.white），
),
),
),
),
大小盒子(
身高：25，
),
],
),
);
}
}
类GetSignup扩展了无状态小部件{
GetTextField GetTextField=GetTextField（）；
@凌驾
小部件构建（构建上下文）{
扩大回报(
弹性：1，
孩子：排(
mainAxisAlignment:mainAxisAlignment.spaceBetween，
儿童：[
手势检测器(
onTap:（）{
打印（'user name:${getTextField.username}'）；
打印（'user email:{getTextField.email}'）；
打印（'user password:${getTextField.password}'）；
},
孩子：圆环星(
背景颜色：Colors.grey.shade800，
半径：40，
子：图标(
Icons.arrow_back，
颜色：颜色，白色，
),
),
),
正文(
"انشئ حسابك",
样式：TextStyle(
尺寸：25，
fontWeight:fontWeight.bold，
),
),
],
),
);
}
}

方法2:

class SignupScreen extends StatefulWidget {
  static const id = "signup_screen";
  @override
  _SignupScreenState createState() => _SignupScreenState();
}

class _SignupScreenState extends State<SignupScreen> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: CustomPaint(
        painter: BackgroundSignup(),
        child: Stack(
          children: <Widget>[
            Padding(
              padding: EdgeInsets.symmetric(
                horizontal: 35,
              ),
              child: Column(
                children: <Widget>[
                  GetHeader(),
                  GetTextField(),
                  GetSignup(),
                  GetButtonRow(),
                ],
              ),
            ),
            GetBackButton(),
          ],
        ),
      ),
    );
  }
}

class GetTextField extends StatelessWidget {
  String email;
  String password;
  String username;
  @override
  Widget build(BuildContext context) {
    return Expanded(
      flex: 4,
      child: Column(
        mainAxisAlignment: MainAxisAlignment.end,
        children: <Widget>[
          SizedBox(
            height: 15,
          ),
          Directionality(
            textDirection: TextDirection.rtl,
            child: TextField(
              onChanged: (value) {
                username = value;
              },
              textAlign: TextAlign.start,
              decoration: InputDecoration(
                labelText: "الاسم كاملا",
                labelStyle:
                    TextStyle(color: Colors.white, fontWeight: FontWeight.bold),
                enabledBorder: UnderlineInputBorder(
                  borderSide: BorderSide(color: Colors.white),
                ),
              ),
            ),
          ),
          SizedBox(
            height: 15,
          ),
          Directionality(
            textDirection: TextDirection.rtl,
            child: TextField(
              onChanged: (value) {
                email = value;
              },
              textAlign: TextAlign.start,
              decoration: InputDecoration(
                labelText: "الإيميل",
                labelStyle:
                    TextStyle(color: Colors.white, fontWeight: FontWeight.bold),
                enabledBorder: UnderlineInputBorder(
                  borderSide: BorderSide(color: Colors.white),
                ),
              ),
            ),
          ),
          SizedBox(
            height: 15,
          ),
          Directionality(
            textDirection: TextDirection.rtl,
            child: TextField(
              onChanged: (value) {
                password = value;
              },
              obscureText: true,
              textAlign: TextAlign.start,
              decoration: InputDecoration(
                labelText: "كلمة السر",
                labelStyle:
                    TextStyle(color: Colors.white, fontWeight: FontWeight.bold),
                enabledBorder: UnderlineInputBorder(
                  borderSide: BorderSide(color: Colors.white),
                ),
              ),
            ),
          ),
          SizedBox(
            height: 25,
          ),
        ],
      ),
    );
  }
}

class GetSignup extends StatelessWidget {
  GetTextField getTextField = GetTextField();

  @override
  Widget build(BuildContext context) {
    return Expanded(
      flex: 1,
      child: Row(
        mainAxisAlignment: MainAxisAlignment.spaceBetween,
        children: <Widget>[
          GestureDetector(
            onTap: () {
              print('user name: ${getTextField.username}');
              print('user email: {getTextField.email}');
              print('user password: ${getTextField.password}');
            },
            child: CircleAvatar(
              backgroundColor: Colors.grey.shade800,
              radius: 40,
              child: Icon(
                Icons.arrow_back,
                color: Colors.white,
              ),
            ),
          ),
          Text(
            "انشئ حسابك",
            style: TextStyle(
              fontSize: 25,
              fontWeight: FontWeight.bold,
            ),
          ),
        ],
      ),
    );
  }
}

class SignupScreen extends StatefulWidget {
  static const id = "signup_screen";
  @override
  _SignupScreenState createState() => _SignupScreenState();
}

class _SignupScreenState extends State<SignupScreen> {
  GetTextField getTextField = GetTextField();
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: CustomPaint(
        painter: BackgroundSignup(),
        child: Stack(
          children: <Widget>[
            Padding(
              padding: EdgeInsets.symmetric(
                horizontal: 35,
              ),
              child: Column(
                children: <Widget>[
                  GetHeader(),
                  GetTextField(),
                  GetSignup(
                    username: getTextField.username,
                    email: getTextField.email,
                    password: getTextField.password,
                  ),
                  GetButtonRow(),
                ],
              ),
            ),
            GetBackButton(),
          ],
        ),
      ),
    );
  }
}

class GetTextField extends StatelessWidget {
  String email;
  String password;
  String username;
  @override
  Widget build(BuildContext context) {
    return Expanded(
      flex: 4,
      child: Column(
        mainAxisAlignment: MainAxisAlignment.end,
        children: <Widget>[
          SizedBox(
            height: 15,
          ),
          Directionality(
            textDirection: TextDirection.rtl,
            child: TextField(
              onChanged: (value) {
                username = value;
              },
              textAlign: TextAlign.start,
              decoration: InputDecoration(
                labelText: "الاسم كاملا",
                labelStyle:
                    TextStyle(color: Colors.white, fontWeight: FontWeight.bold),
                enabledBorder: UnderlineInputBorder(
                  borderSide: BorderSide(color: Colors.white),
                ),
              ),
            ),
          ),
          SizedBox(
            height: 15,
          ),
          Directionality(
            textDirection: TextDirection.rtl,
            child: TextField(
              onChanged: (value) {
                email = value;
              },
              textAlign: TextAlign.start,
              decoration: InputDecoration(
                labelText: "الإيميل",
                labelStyle:
                    TextStyle(color: Colors.white, fontWeight: FontWeight.bold),
                enabledBorder: UnderlineInputBorder(
                  borderSide: BorderSide(color: Colors.white),
                ),
              ),
            ),
          ),
          SizedBox(
            height: 15,
          ),
          Directionality(
            textDirection: TextDirection.rtl,
            child: TextField(
              onChanged: (value) {
                password = value;
              },
              obscureText: true,
              textAlign: TextAlign.start,
              decoration: InputDecoration(
                labelText: "كلمة السر",
                labelStyle:
                    TextStyle(color: Colors.white, fontWeight: FontWeight.bold),
                enabledBorder: UnderlineInputBorder(
                  borderSide: BorderSide(color: Colors.white),
                ),
              ),
            ),
          ),
          SizedBox(
            height: 25,
          ),
        ],
      ),
    );
  }
}

class GetSignup extends StatelessWidget {
  final username;
  final email;
  final password;
  GetSignup({this.username, this.email, this.password});
  @override
  Widget build(BuildContext context) {
    return Expanded(
      flex: 1,
      child: Row(
        mainAxisAlignment: MainAxisAlignment.spaceBetween,
        children: <Widget>[
          GestureDetector(
            onTap: () {
              print('user name: $username');
              print('user email: $email');
              print('user password: $password');
            },
            child: CircleAvatar(
              backgroundColor: Colors.grey.shade800,
              radius: 40,
              child: Icon(
                Icons.arrow_back,
                color: Colors.white,
              ),
            ),
          ),
          Text(
            "انشئ حسابك",
            style: TextStyle(
              fontSize: 25,
              fontWeight: FontWeight.bold,
            ),
          ),
        ],
      ),
    );
  }
}

class SignupScreen扩展StatefulWidget{
静态常量id=“注册屏幕”；
@凌驾
_SignupScreenState createState（）=>\u SignupScreenState（）；
}
类_SignupScreenState扩展状态{
GetTextField GetTextField=GetTextField（）；
@凌驾
小部件构建（构建上下文）{
返回脚手架(
车身：定制喷漆(
画家：背景签名（），
子：堆栈(
儿童：[
填充物(
填充：EdgeInsets.symmetric(
横向：35，
),
子：列(
儿童：[
GetHeader（），
GetTextField（），
注册(
用户名：getTextField.username，
电子邮件：getTextField.email，
密码：getTextField.password，
),
GetButtonRow（），
],
),
),
GetBackButton（），
],
),
),
);
}
}
类GetTextField扩展了无状态小部件{
字符串电子邮件；
字符串密码；
字符串用户名；
@凌驾
小部件构建（构建上下文）{
扩大回报(
弹性：4，
子：列(
class SignupScreen extends StatefulWidget {
  static const id = "signup_screen";
  @override
  _SignupScreenState createState() => _SignupScreenState();
}

class _SignupScreenState extends State<SignupScreen> {
  String email;
  String username;
  String password;
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: CustomPaint(
        painter: BackgroundSignup(),
        child: Stack(
          children: <Widget>[
            Padding(
              padding: EdgeInsets.symmetric(
                horizontal: 35,
              ),
              child: Column(
                children: <Widget>[
                  GetHeader(),
                  GetTextField(
                    onEmail: (value) {
                      setState(() {
                        value = email;
                      });
                    },
                    onUsername: (value) {
                      setState(() {
                        value = username;
                      });
                    },
                    onPassword: (value) {
                      setState(() {
                        value = password;
                      });
                    },
                  ),
                  GetSignup(
                    username: username,
                    email: email,
                    password: password,
                  ),
                  GetButtonRow(),
                ],
              ),
            ),
            GetBackButton(),
          ],
        ),
      ),
    );
  }
}

class GetTextField extends StatelessWidget {
  Function(String) onEmail;
  Function(String) onPassword;
  Function(String) onUsername;
  GetTextField({Key key, this.onEmail, this.onPassword, this.onUsername})
      : super(key: key);
  @override
  Widget build(BuildContext context) {
    return Expanded(
      flex: 4,
      child: Column(
        mainAxisAlignment: MainAxisAlignment.end,
        children: <Widget>[
          SizedBox(
            height: 15,
          ),
          Directionality(
            textDirection: TextDirection.rtl,
            child: TextField(
              onChanged: onUsername,
              textAlign: TextAlign.start,
              decoration: InputDecoration(
                labelText: "الاسم كاملا",
                labelStyle:
                    TextStyle(color: Colors.white, fontWeight: FontWeight.bold),
                enabledBorder: UnderlineInputBorder(
                  borderSide: BorderSide(color: Colors.white),
                ),
              ),
            ),
          ),
          SizedBox(
            height: 15,
          ),
          Directionality(
            textDirection: TextDirection.rtl,
            child: TextField(
              onChanged: onEmail,
              textAlign: TextAlign.start,
              decoration: InputDecoration(
                labelText: "الإيميل",
                labelStyle:
                    TextStyle(color: Colors.white, fontWeight: FontWeight.bold),
                enabledBorder: UnderlineInputBorder(
                  borderSide: BorderSide(color: Colors.white),
                ),
              ),
            ),
          ),
          SizedBox(
            height: 15,
          ),
          Directionality(
            textDirection: TextDirection.rtl,
            child: TextField(
              onChanged: onPassword,
              obscureText: true,
              textAlign: TextAlign.start,
              decoration: InputDecoration(
                labelText: "كلمة السر",
                labelStyle:
                    TextStyle(color: Colors.white, fontWeight: FontWeight.bold),
                enabledBorder: UnderlineInputBorder(
                  borderSide: BorderSide(color: Colors.white),
                ),
              ),
            ),
          ),
          SizedBox(
            height: 25,
          ),
        ],
      ),
    );
  }
}

class GetSignup extends StatelessWidget {
  final username;
  final email;
  final password;
  GetSignup({Key key, this.username, this.email, this.password})
      : super(key: key);
  @override
  Widget build(BuildContext context) {
    return Expanded(
      flex: 1,
      child: Row(
        mainAxisAlignment: MainAxisAlignment.spaceBetween,
        children: <Widget>[
          GestureDetector(
            onTap: () {
              //TODO: fill circle avatar
              print('user name: $username');
              print('user email: $email');
              print('user password: $password');
            },
            child: CircleAvatar(
              backgroundColor: Colors.grey.shade800,
              radius: 40,
              child: Icon(
                Icons.arrow_back,
                color: Colors.white,
              ),
            ),
          ),
          Text(
            "انشئ حسابك",
            style: TextStyle(
              fontSize: 25,
              fontWeight: FontWeight.bold,
            ),
          ),
        ],
      ),
    );
  }
}