Age calculator in flutter

In this post we will see a simple age calculator for Android and iOS.

We will need two external packages

flutter_cupertino_date_picker: ^0.8.0 //for datepicker in ios
intl: ^0.15.8 // for formatting of date

Then, Create a stateful class as AgeCalculator

Following is function which calculates age. It take birthdate and returns age in int.

calculateAge(DateTime birthDate) {
DateTime currentDate = DateTime.now();
int age = currentDate.year - birthDate.year;
int month1 = currentDate.month;
int month2 = birthDate.month;
if (month2 > month1) {
age--;
} else if (month1 == month2) {
int day1 = currentDate.day;
int day2 = birthDate.day;
if (day2 > day1) {
age--;
}
}
return age;
}

Following is function which is used to call show date picker. It checks if device is android or ios and according to that it show datepicker.

Note: Both platform have different native date picker.

selectDate(BuildContext context, DateTime initialDateTime,
{DateTime lastDate}) async {
Completer completer = Completer();
String _selectedDateInString;
if (Platform.isAndroid)
showDatePicker(
context: context,
initialDate: initialDateTime,
firstDate: DateTime(1970),
lastDate: lastDate == null
? DateTime(initialDateTime.year + 10)
: lastDate)
.then((temp) {
if (temp == null) return null;
completer.complete(temp);
setState(() {});
});
else
DatePicker.showDatePicker(
context,
dateFormat: 'yyyy-mmm-dd',
locale: 'en',
onConfirm2: (temp, selectedIndex) {
if (temp == null) return null;
completer.complete(temp);

setState(() {});
},
);
return completer.future;
}

** If you didn’t understood code then do comment. I will then explain full code.

Following is simple ui code with button and text to show birthdate and age.

String birthDate = "";
int age = -1;
TextStyle valueTextStyle=TextStyle(
fontWeight: FontWeight.bold,
fontSize: 20,
);
TextStyle textTextStyle=TextStyle(

fontSize: 16,
);
TextStyle buttonTextStyle=TextStyle(
color: Colors.white,
fontSize: 16,
);
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("Age Calculator"),
),
body: Container(
alignment: Alignment.center,
padding: EdgeInsets.all(32),
child: Column(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
(age > -1)
? Column(
children: <Widget>[
Container(
decoration: BoxDecoration(
borderRadius: BorderRadius.all(Radius.elliptical(12, 12)),
border: Border.all(color: Colors.grey)
),
padding: EdgeInsets.all(16),
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Text("BirthDate: ",style: textTextStyle,),
Text("$birthDate",style: valueTextStyle,)
],
),
),
SizedBox(
height: 16,
),
Container(
padding: EdgeInsets.all(16),

decoration: BoxDecoration(
borderRadius: BorderRadius.all(Radius.elliptical
(12, 12)),
border: Border.all(color: Colors.grey)
),
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[Text("Age: ",style: textTextStyle,), Text("$age",style: valueTextStyle,)],
),
)
],
)
: Text("Press button to see age"),
SizedBox(
height: 32,
),
RaisedButton(
color: Colors.blue,
splashColor: Colors.blue.shade300,
onPressed: () async {
DateTime birthDate = await selectDate(context, DateTime.now(),
lastDate: DateTime.now());
final df = new DateFormat('dd-MMM-yyyy');
this.birthDate = df.format(birthDate);
this.age = calculateAge(birthDate);

setState(() {});
},
child: Container(
padding: EdgeInsets.all(16),
child: Text("Select birthdate".toUpperCase(),style: buttonTextStyle,)),
)
],
),
),
);
}

Screenshots:

That’s it for now. Stay tuned for more.

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#Happy Coding

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Writer , Speaker, Instructor and Flutter Dev

Writer , Speaker, Instructor and Flutter Dev