Method Overriding in Dart

In this lesson, you will learn about method overriding in Dart. Method overriding allows a child class to provide its own implementation of a method that is already defined in its parent class.

This is commonly used when different objects share a common structure but behave differently in real-world scenarios.

What Is Method Overriding?

Method overriding occurs when:

• A child class inherits from a parent class
• The child class defines a method with the same name
• The method has the same parameters as the parent method

Dart uses the @override annotation to clearly indicate that a method is being overridden.

Real-World Example Scenario

Consider a company where different employees receive salary details in different formats.

All employees have basic information, but managers need additional details.

Parent Class Example

class Employee {
  String name;
  double salary;

  Employee(this.name, this.salary);

  void showDetails() {
    print('Employee Name: $name');
    print('Salary: $salary');
  }
}

The Employee class provides a default implementation of the showDetails() method.

Overriding the Method in Child Class

Now let’s override the method for a manager.

class Manager extends Employee {
  double bonus;

  Manager(String name, double salary, this.bonus)
      : super(name, salary);

  @override
  void showDetails() {
    print('--- Manager Details ---');
    print('Name: $name');
    print('Salary: $salary');
    print('Bonus: $bonus');
  }
}

Here, the Manager class provides its own implementation of showDetails().

Using Overridden Methods

void main() {
  Employee emp = Employee('Rahul', 55000);
  emp.showDetails();

  print('');

  Manager mgr = Manager('Anita', 85000, 15000);
  mgr.showDetails();
}

Although both objects use showDetails(), each class executes its own version of the method.

Calling Parent Method Using super

Sometimes, you may want to extend the parent method instead of replacing it.

class SeniorManager extends Manager {
  SeniorManager(String name, double salary, double bonus)
      : super(name, salary, bonus);

  @override
  void showDetails() {
    super.showDetails();
    print('Level: Senior Management');
  }
}

Why Method Overriding Is Important

• Allows customization of inherited behavior
• Supports polymorphism
• Makes applications flexible and scalable
• Improves real-world modeling of systems

Common Rules for Method Overriding

• Method name must be the same
• Parameters must match
• Return type must be compatible
• Use @override for clarity

📝 Practice Exercises

Exercise 1

Create a parent class Vehicle with a method fuelType().

Exercise 2

Create a child class ElectricCar that overrides fuelType().

Exercise 3

Print different fuel types for different vehicles.

✅ Practice Answers

class Vehicle {
  void fuelType() {
    print('Fuel: Petrol');
  }
}

class ElectricCar extends Vehicle {
  @override
  void fuelType() {
    print('Fuel: Electricity');
  }
}

void main() {
  Vehicle v1 = Vehicle();
  Vehicle v2 = ElectricCar();

  v1.fuelType();
  v2.fuelType();
}

What’s Next?

In the next lesson, you will learn about Abstract Classes — how to define incomplete classes and enforce structure across multiple child classes.