Forms in Flutter

Forms are an integral part of all modern mobile and web applications. It is mainly used to interact with the app as well as gather information from the users. They can perform many tasks, which depend on the nature of your business requirements and logic, such as authentication of the user, adding user, searching, filtering, ordering, booking, etc. A form can contain text fields, buttons, checkboxes, radio buttons, etc.

Adding Checkbox

Flutter provides a Form widget to create a form. The form widget acts as a container, which allows us to group and validate the multiple form fields. The form widget uses child widget Checkbox to provide the users are used  to let a user to select one or more options of a limited number of choices. This widget renders a material design text field and also allows us to display validation errors when they occur.

Coding the Form

import ‘package:flutter/material.dart’;

void main() {
  runApp(MyApp());
}
class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: ‘MYAPP’,
      theme: ThemeData(
        // This is the theme of your application.
        //
        // Try running your application with “flutter run”. You’ll see the
        // application has a blue toolbar. Then, without quitting the app, try
        // changing the primarySwatch below to Colors.green and then invoke
        // “hot reload” (press “r” in the console where you ran “flutter run”,
        // or simply save your changes to “hot reload” in a Flutter IDE).
        // Notice that the counter didn’t reset back to zero; the application
        // is not restarted.
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: ‘AADI INFOTECH’),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  // This widget is the home page of your application. It is stateful, meaning
  // that it has a State object (defined below) that contains fields that affect
  // how it looks.

  // This class is the configuration for the state. It holds the values (in this
  // case the title) provided by the parent (in this case the App widget) and
  // used by the build method of the State. Fields in a Widget subclass are
  // always marked “final”.

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  bool checkBoxValue = false;
 bool checkBoxValue1 = false;

 //  bool _isChecked = false;
 // String _currText = ”;

 //List<String> text = [“PHP”, “JAVA”, “FLUTTER”];

  var currentSelectedValue;
var deviceTypes = [“Mac”, “Windows”, “Mobile”];
  int _counter = 0;
  int selectedRadioTile;
      @override
      void initState() {
        super.initState();
        
        selectedRadioTile = 0;
      }
      
      setSelectedRadioTile(int val) {
        setState(() {
          selectedRadioTile = val;
        });
      }
      
  void _incrementCounter() {
    setState(() {
      // This call to setState tells the Flutter framework that something has
      // changed in this State, which causes it to rerun the build method below
      // so that the display can reflect the updated values. If we changed
      // _counter without calling setState(), then the build method would not be
      // called again, and so nothing would appear to happen.
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {

    // This method is rerun every time setState is called, for instance as done
    // by the _incrementCounter method above.
    //
    // The Flutter framework has been optimized to make rerunning build methods
    // fast, so that you can just rebuild anything that needs updating rather
    // than having to individually change instances of widgets.
          
    return Scaffold(
       
       // to set background color to the body
       backgroundColor: Color.fromARGB(216,197,197, 1),

      appBar: AppBar(
        // Here we take the value from the MyHomePage object that was created by
        // the App.build method, and use it to set our appbar title.
        title: Text(widget.title),
      ),
      body: SingleChildScrollView(
                 
        // Center is a layout widget. It takes a single child and positions it
        // in the middle of the parent.
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.center,
           mainAxisSize: MainAxisSize.max,
           mainAxisAlignment: MainAxisAlignment.center,  
        
         
          // Column is also a layout widget. It takes a list of children and
          // arranges them vertically. By default, it sizes itself to fit its
          // children horizontally, and tries to be as tall as its parent.
          //
          // Invoke “debug painting” (press “p” in the console, choose the
          // “Toggle Debug Paint” action from the Flutter Inspector in Android
          // Studio, or the “Toggle Debug Paint” command in Visual Studio Code)
          // to see the wireframe for each widget.
          //
          // Column has various properties to control how it sizes itself and
          // how it positions its children. Here we use mainAxisAlignment to
          // center the children vertically; the main axis here is the vertical
          // axis because Columns are vertical (the cross axis would be
          // horizontal).

          children: <Widget>[
         
                Align(alignment: Alignment.center,),
              
   Padding(
            padding: const  EdgeInsets.only(right: 50, left: 50),),
   
      /* ============================== text-field  ===================================================*/

            Container(
    
              padding: EdgeInsets.all(20.0),
               child: const Text(
                        ‘Custom Form’,
                        style: TextStyle(fontSize: 30)
                      ),
               
            ),
              Container(
                  padding: EdgeInsets.all(20.0),
                  margin: const EdgeInsets.only(right: 50, left: 50),
                  width: 400.0,
               child:  TextFormField(
              
                 decoration: new InputDecoration(                    
                                     
                        labelText: “Enter First Name”,
                         icon: new Icon(Icons.person),
                        fillColor: Colors.white,
                         
                        
                        border: new OutlineInputBorder(
                          borderRadius: new BorderRadius.circular(25.0),
                          borderSide: new BorderSide(
                          ),
                        ),
                        //fillColor: Colors.green
                      ),

                      validator: (val) {
                        if(val.length==0) {
                          return “Please enter name”;
                        }else{
                          return null;
                        }
                      },
              
            )

              ),
           
           Container(
               padding: EdgeInsets.all(20.0),
                width: 400.0,
                 margin: const EdgeInsets.only(right: 50, left: 50),
             child: TextFormField(
               
                 decoration: new InputDecoration(
                        labelText: “Enter Phone Number”,
                         icon: new Icon(Icons.phone),
                        fillColor: Colors.white,
                        border: new OutlineInputBorder(
                          borderRadius: new BorderRadius.circular(25.0),
                          borderSide: new BorderSide(
                          ),
                        ),
                        //fillColor: Colors.green
                      ),

                      validator: (val) {
                        if(val.length==0) {
                          return “Please enter name”;
                        }else{
                          return null;
                        }
                      },
              
            ),

           ),

/* ====================================== text area ==================================================*/
                      Container(
                      padding: EdgeInsets.all(20.0),
                                      width: 400.0,
                                      margin: const EdgeInsets.only(right: 50, left: 50),
                      child:TextField(
                      maxLines: 4,
                      decoration: InputDecoration(
                                            labelText: “Enter Addresss”,
                                              icon: new Icon(Icons.home),
                                              fillColor: Colors.white,
                                              border: new OutlineInputBorder(
                                                borderRadius: new BorderRadius.circular(25.0),
                                                borderSide: new BorderSide(
                                                ),
                                              ),

                      ),

                      ),
                      ),
            
  /*======================================= Radion buttons ===================================*/  

            Container(
                alignment: Alignment.topLeft,
                 padding: EdgeInsets.all(20.0),
                width: 400.0,
                 margin: const EdgeInsets.only(right: 50, left: 50),
                child: const Text(
                        ‘Gender’,
                        style: TextStyle(fontSize: 20)
                      ),

            ),
            Container(
               
              width: 400.0,
                margin: const EdgeInsets.only(right: 50, left: 100),

              child:  RadioListTile(

                    value: 1,
                    groupValue: selectedRadioTile,
                  
                    title: Text(“Female”),
                    onChanged: (val) {
                      print(“Radio Tile pressed $val”);
                      setSelectedRadioTile(val);
                    },
                    activeColor: Colors.blue,
                    
                   
                    selected: true,
                  ),

            ),
           
           Container(
              
              width: 400.0,
                margin: const EdgeInsets.only(right: 50, left: 100),
             child: RadioListTile(
                    
                    value: 2,
                    groupValue: selectedRadioTile,
                   
                    title: Text(“Male”),
                    onChanged: (val) {
                      print(“Radio Tile pressed $val”);
                      setSelectedRadioTile(val);
                    },
                    activeColor: Colors.blue,
                   
                    selected: false,
                  ),

           ),

/* =============================================dropdown list ===============================================*/

            Container(
                width: 300.0,
                margin: const EdgeInsets.only(right: 50,left:80),
                child:  DropdownButton<String>(
                      hint: Text(‘Select Device’,
                             style: TextStyle(color:Colors.blue,
                             fontSize: 20,
                             fontStyle: FontStyle.italic,
                             fontWeight: FontWeight.w700),                      
                            ),
                      value: currentSelectedValue,
                      isDense: true,
                      onChanged: (newValue) {
                        setState(() {
                          currentSelectedValue = newValue;
                        });
                        print(currentSelectedValue);
                      },
                      items: deviceTypes.map((String value) {
                        return DropdownMenuItem<String>(
                          value: value,
                          child: Text(value),
                        );
                      }).toList(),
                    ),
                  
             ),
/* ================================== Checkbox ==============================================*/
                Container(
                alignment: Alignment.topLeft,
                 padding: EdgeInsets.all(20.0),
                width: 400.0,
                 margin: const EdgeInsets.only(right: 50, left: 50),
                child: const Text(
                        ‘Languages’,
                        style: TextStyle(fontSize: 20)
                      ),

                ),
            Container(
                width: 300.0,
                margin: const EdgeInsets.only(right: 50,left:80),          

                        child: Row(
                        children: <Widget>[
                          Checkbox(
                              value: checkBoxValue,
                              onChanged: (bool value){
                                print(value);
                                setState(() {
                                  checkBoxValue = value;
                                });
                              }


                          ),
                          Text(“FLUTTER”)
                        ],

                        ),

                                    ),

                          Container(
                                        width: 300.0,
                                        margin: const EdgeInsets.only(right: 50,left:80),

                        child: Row(
                        children: <Widget>[
                          Checkbox(
                              value: checkBoxValue1,
                              onChanged: (bool value){
                                print(value);
                                setState(() {
                                  checkBoxValue1 = value;
                                });
                              }


                          ),
                          Text(“PHP”)
                        ],


                        ),

                                    ),

/* =================================== submit button ==============================================*/
             RaisedButton(
               
                      onPressed: () {},
                  shape: RoundedRectangleBorder(
                        borderRadius: new BorderRadius.circular(18.0),
                        side: BorderSide(color: Colors.red)
                      ),
                      child: const Text(
                        ‘Submit’,
                        style: TextStyle(fontSize: 25, 
                                          color: Colors.blue,
                 
                        )
                      ),
                    ),

/*=================================end widget part ================================================== */    
 
          ],

        ),
    
    ),
      // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}
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