How can the GPA Calculator in Flutter be made functional?

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To make the GPA calculator functional, you can follow these steps in Flutter:

1. Create a class called “Course” with attributes such as “name”, “grade”, and “credit hours”.

2. Create a list of type “Course” to store every inputted course.

3. Create a form where the user can input the course name, grade, and credit hours.

4. When the form is submitted, create a new “Course” object and append it to the list of courses.

5. Calculate the total credit hours and quality points by iterating through the list of courses.

6. Display the calculated GPA to the user.

Here is an example implementation of the above steps:

class Course {
  String name;
  String grade;
  int creditHours;

  Course({this.name, this.grade, this.creditHours});
}

List<Course> courses = [];

class GPAcalculator extends StatefulWidget {
  @override
  _GPAcalculatorState createState() => _GPAcalculatorState();
}

class _GPAcalculatorState extends State<GPAcalculator> {
  final _formKey = GlobalKey<FormState>();
  String _courseName;
  String _grade;
  int _creditHours;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text("GPA Calculator")),
      body: Padding(
        padding: EdgeInsets.all(16.0),
        child: Form(
          key: _formKey,
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: <Widget>[
              TextFormField(
                decoration: InputDecoration(labelText: 'Course Name'),
                validator: (value) {
                  if (value.isEmpty) {
                    return 'Please enter course name';
                  }
                  return null;
                },
                onSaved: (value) {
                  _courseName = value;
                },
              ),
              TextFormField(
                decoration: InputDecoration(labelText: 'Grade'),
                validator: (value) {
                  if (value.isEmpty) {
                    return 'Please enter grade';
                  }
                  return null;
                },
                onSaved: (value) {
                  _grade = value;
                },
              ),
              TextFormField(
                decoration: InputDecoration(labelText: 'Credit Hours'),
                keyboardType: TextInputType.number,
                validator: (value) {
                  if (value.isEmpty) {
                    return 'Please enter credit hours';
                  }
                  return null;
                },
                onSaved: (value) {
                  _creditHours = int.parse(value);
                },
              ),
              Padding(
                padding: const EdgeInsets.symmetric(vertical: 16.0),
                child: RaisedButton(
                  onPressed: () {
                    if (_formKey.currentState.validate()) {
                      _formKey.currentState.save();
                      Course newCourse = Course(
                          name: _courseName,
                          grade: _grade,
                          creditHours: _creditHours);
                      courses.add(newCourse);
                      _formKey.currentState.reset();
                      setState(() {});
                    }
                  },
                  child: Text('Submit'),
                ),
              ),
              Divider(),
              Text('Results:'),
              Text('Total Credit Hours: ${_totalCreditHours()}'),
              Text('Quality Points: ${_qualityPoints()}'),
              Text('GPA: ${_calculateGPA()}')
            ],
          ),
        ),
      ),
    );
  }

  int _totalCreditHours() {
    int total = 0;
    for (var course in courses) {
      total += course.creditHours;
    }
    return total;
  }

  double _qualityPoints() {
    double total = 0.0;
    for (var course in courses) {
      switch (course.grade) {
        case 'A':
          total += (4.0 * course.creditHours);
          break;
        case 'B':
          total += (3.0 * course.creditHours);
          break;
        case 'C':
          total += (2.0 * course.creditHours);
          break;
        case 'D':
          total += (1.0 * course.creditHours);
          break;
        default:
          break;
      }
    }
    return total;
  }

  double _calculateGPA() {
    return (_qualityPoints() / _totalCreditHours());
  }
}

Note: This is just an example implementation and can be modified according to your specific requirements.