What is the mixin keyword in Dart?
Why Interviewers Ask This
Mid-level Flutter roles require deep understanding of this topic. Interviewers ask this to separate candidates who truly understand the mechanics from those who only know surface-level concepts.
Answer
A mixin is a way to reuse code across multiple class hierarchies without inheritance. Declare a mixin with mixin MyMixin { ... } and apply it with the with keyword: class MyClass extends BaseClass with MyMixin. Mixins cannot have constructors. A class can apply multiple mixins. They are widely used in Flutter for capabilities like TickerProviderStateMixin (provides vsync for animations) and AutomaticKeepAliveClientMixin (preserves scroll position).
Common Mistake
Candidates often give textbook answers here. Interviewers are more impressed when you relate the concept to a specific problem you solved in a real Flutter project.