Dart: Abstract Method

• Abstract methods can only exist within an abstract class.

• To make a method abstract, use a semicolon (;) instead of the method body.

    void talk (); // Abstract method
    void walk (); // Abstract method
  

• Normal classes can extend the abstract class, but they have to override every abstract method.

• You can also create normal methods in the abstract class. And to override normal method is not mandatory.

• The abstract class will only complain when you don't override the abstract method.

// Define an abstract class named Person
abstract class Person {
  // Abstract method to represent walking behavior
  void walk();  // Abstract Method

  // Abstract method to represent talking behavior
  void talk();  // Abstract Method
}

// Define a concrete class named Jinali which extends Person
class Jinali extends Person {
  // Implementing the walk method from the abstract class
  @override
  void walk() {
    print("Jinali can walk");
  }

  // Implementing the talk method from the abstract class
  @override
  void talk() {
    print("Jinali can talk");
  }
}

// Main function, the entry point of the program
void main() {
  // Creating an instance of Jinali class
  Jinali jinali = new Jinali();

  // Calling the talk method of Jinali class
  jinali.talk(); // Output: Jinali can talk

  // Calling the walk method of Jinali class
  jinali.walk(); // Output: Jinali can walk
}

Conclusion:

• Abstract Methods are special methods found only in abstract classes.

• When a class extends an abstract class, it must provide implementations for all the abstract methods in that class.