Abstract

• To define a class that doesn't require a full, concrete implementation of its entire interface, use the abstract modifier.

• Abstract classes cannot be constructed from any library, whether its own or an outside library.

•   abstract class Vehicle {
      void moveForward(int meters);
  
    }
  

•   abstract class Animal {
      void makeSound(); // Abstract method
    }
  
    class Dog extends Animal {
      @override
      void makeSound() {
        print('Woof!');
      }
    }
  
    class Cat extends Animal {
      @override
      void makeSound() {
        print('Meow!');
      }
    }
  
    void main() {
  
      Animal dog = Dog(); // OK
      Animal cat = Cat(); // OK
  
      dog.makeSound(); // Output: Woof!
      cat.makeSound(); // Output: Meow!
  
    }
  

•   Woof!
    Meow!
  
    Exited.