Dart Language
What is the difference between final, const, and static in Dart?
final means assigned once at runtime; const means assigned at compile-time (deeply immutable); static means...
20 XP4m
Dart Language
25 questions
Null safety, async, isolates, Dart 3 features
Dart Language
How does Dart's sound null safety work?
Dart's sound null safety means non-nullable types can never be null at runtime — the compiler enforces this...
20 XP5m
Dart Language
Explain Dart's async/await, Future, and the microtask queue
Dart is single-threaded with an event loop. async/await syntactic sugar wraps code in Future continuations....
30 XP7m
Dart Language
What are Dart Streams and how do single-subscription vs broadcast streams differ?
A Dart Stream is an asynchronous sequence of events. Single-subscription streams (default) allow only one l...
30 XP5m
Dart Language
What are Dart Isolates and when should you use them?
Isolates are Dart's concurrency primitive — independent workers with their own memory heap. They communicat...
50 XP6m
Dart Language
How do Dart mixins work and what are the restrictions?
Mixins allow sharing methods across class hierarchies without inheritance. The 'on' keyword restricts which...
30 XP5m
Dart Language
What are Dart extension methods and when should you use them?
Extension methods add new methods to existing types without subclassing or wrapping. They're resolved stati...
20 XP3m
Dart Language
What are factory constructors in Dart and what are the 3 main patterns?
Factory constructors can return existing instances (caching/singleton), return subtype instances (polymorph...
30 XP5m
Dart Language
How do generics work in Dart, including bounded generics?
Dart generics use type parameters <T> for type-safe collections and classes. Bounded generics <T extends So...
30 XP4m
Dart Language
What are Dart 3 Records and how does pattern matching work?
Dart 3 Records are anonymous, immutable value types that group multiple values. Pattern matching in switch ...
50 XP6m
Dart Language
What are sealed classes in Dart 3 and how do they enable exhaustive matching?
Sealed classes restrict which classes can extend them (only within the same library). This gives the compil...
50 XP5m
Dart Language
How do enhanced enums work in Dart 3?
Dart 2.17+ enhanced enums can have fields, constructors, methods, and implement interfaces — making them fu...
20 XP3m
Dart Language
When and how should you use the 'late' keyword in Dart?
late defers initialization of a non-nullable variable — it must be initialized before first access (runtime...
20 XP3m
Dart Language
What is Dart's cascade notation (..) and when should you use it?
The cascade operator (..) allows chaining multiple operations on the same object without repeating the vari...
10 XP2m
Dart Language
How do spread operators, collection if, and collection for work in Dart?
The spread operator (...) flattens an iterable into a list/set/map literal. Collection if adds elements con...
20 XP3m
Dart Language
How do typedefs work in Dart and why are they useful?
typedef creates a named alias for function types or complex generic types, improving code readability and a...
20 XP2m
Dart Language
How should you implement == and hashCode in Dart?
Override both == and hashCode together — they form a contract. Objects that are == must have the same hashC...
20 XP3m
Dart Language
What are Dart Zones and how are they used for error handling?
Zones provide a context for asynchronous code that allows overriding behaviors like error handling, schedul...
80 XP5m
Dart Language
What is the difference between var, dynamic, and Object in Dart?
var uses type inference (becomes the inferred type); dynamic opts out of type checking entirely; Object is ...
10 XP2m
Dart Language
What is the difference between abstract class, interface, and mixin in Dart?
Every Dart class is implicitly an interface. abstract classes define contracts + optional implementations; ...
30 XP4m
Dart Language
What are named, positional, and required parameters in Dart?
Positional parameters are passed by position; named parameters are passed by name (in braces); required key...
10 XP3m
Dart Language
How does Dart's event loop work with event queue and microtask queue?
Dart's event loop runs in a single thread: execute sync code → drain microtask queue completely → process o...
50 XP5m
Dart Language
What is the fat arrow (=>) syntax in Dart and when should you use it?
The fat arrow => is syntactic sugar for a single-expression function body: int add(int a, int b) => a + b; ...
10 XP1m
Dart Language
How do Dart's List, Set, and Map compare in performance?
List: O(1) index access, O(n) search; Set/Map (hash-based): O(1) lookup/insert/delete on average. Use Set w...
30 XP3m
Dart Language
How does string interpolation and multiline strings work in Dart?
Dart uses $variable or ${expression} for string interpolation, triple quotes for multiline strings (''' or ...
10 XP2m