What is the difference between an abstract class and a mixin?

Abstract class:

• Can have both regular and abstract methods and fields.
• Cannot instantiate an abstract class directly.
• Can contain constructors.
• Inherited using the extends keyword. Single inheritance is supported.
• Used to define common behavior and structure for subclasses.

Mixin:

• Can contain methods and fields, but cannot define constructors.
• Not intended for instantiation.
• Used to add functionality to classes that does not fit into the inheritance hierarchy.
• Combined with a class using the with keyword. A class can use multiple mixins.

Attribute	Abstract class	Mixin
Instance	Cannot be created directly	Cannot be created
Constructors	Can have	Cannot have
Inheritance	extends (single)	with (multiple)
Main purpose	Define hierarchy	Add behavior

Example of using an abstract class:

abstract class LivingBeing {
  void breathe(); // Abstract method

  void grow() { // Regular method
    print('Growing...');
  }
}

class Human extends LivingBeing {
  @override
  void breathe() {
    print('Breathing with lungs');
  }
}

Example of using a mixin:

mixin Walkable {
  void walk() {
    print('Walking...');
  }
}

mixin Swimmable {
  void swim() {
    print('Swimming...');
  }
}

class Dog with Walkable, Swimmable {
  // The Dog class now has walk() and swim() methods
}