Form field guide for flutter

Padding(  
  padding: EdgeInsets.all(15),  
  child: TextField(  
    keyboardType: TextInputType.number,
    decoration: InputDecoration(  
      border: OutlineInputBorder(),  
      labelText: 'User Name',  
      hintText: 'Enter Your Name',  
    ),  
  ),  
),  
Padding(  
  padding: EdgeInsets.all(15),  
  child: TextField(  
    obscureText: true,  
    decoration: InputDecoration(  
      border: OutlineInputBorder(),  
      labelText: 'Password',  
      hintText: 'Enter Password',  
    ),  
  ),  
),

use suffix/prefix icon in InputDecoration to add.

multiline text field flutter

TextField(
  keyboardType: TextInputType.multiline,
  minLines: 1,//Normal textInputField will be displayed
  maxLines: 5,// when user presses enter it will adapt to it
 );

Drop down select flutter

DropdownButton(
                
  // Initial Value
  value: dropdownvalue,
    
  // Down Arrow Icon
  icon: const Icon(Icons.keyboard_arrow_down),    
    
  // Array list of items
  items: items.map((String items) {
    return DropdownMenuItem(
      value: items,
      child: Text(items),
    );
  }).toList(),
  // After selecting the desired option,it will
  // change button value to selected value
  onChanged: (newValue) { 
    setState(() {
      dropdownvalue = newValue!;
    });
  },
),

check boxes

Checkbox(  
  checkColor: Colors.greenAccent,  
  activeColor: Colors.red,  
  value: this.valuefirst,  
  onChanged: (bool? value) {  
    setState(() {  
      this.valuefirst = value;  
    });  
  },  
),  
Checkbox(  
  value: this.valuesecond,  
  onChanged: (bool? value) {  
    setState(() {  
      this.valuesecond = value;  
    });  
  },  
),

Switch

Switch(
  onChanged: (value) {
    _futureDateToggle = value;
  },
  value: _futureDateToggle,
)