Basic Dart Interview Questions (1-10)
1. What is Dart programming language?
Dart is an object-oriented programming language developed by Google, primarily used for building fast applications across platforms with features like just-in-time (JIT) and ahead-of-time (AOT) compilation.[1][8]
2. What are the key features of Dart?
Dart offers object-oriented programming, garbage collection, async support with Futures and Streams, fast compilation, and rich standard libraries for math, crypto, and HTML.[1][3]
3. How do you define a variable in Dart?
Variables in Dart are declared using var, final, or const. The type can be inferred or explicitly specified.[6]
var name = 'Dart';
final age = 25;
const pi = 3.14;4. What is the difference between var, dynamic, and Object in Dart?
var is type-inferred and immutable at compile time, dynamic allows runtime type changes, and Object is the root class where all types are subtypes.[4]
5. What is a Dart string and how do you create one?
Dart strings are sequences of UTF-16 code units created using single, double quotes, or triple quotes for multi-line strings.[3]
String single = 'Hello Dart';
String multi = '''
Multi-line
string
''';
String interpolated = 'Age: $age';6. What are the types of operators in Dart?
Dart supports arithmetic (+, -, *, /), assignment (=, +=), relational (==, !=, >), logical (&&, ||, !), bitwise (&, |, ^), conditional (?:), and cascade (..) operators.[1]
7. What is the main() function in Dart?
The main() function is the entry point of every Dart application where execution begins.[2]
void main() {
print('Hello, Dart!');
}8. What is Fat Arrow Notation in Dart?
Fat arrow notation (=>) provides a concise way to write single-expression functions or methods.[4]
var add = (int a, int b) => a + b;
print(add(2, 3)); // 59. What are the types of lists in Dart?
Dart has fixed-length lists (immutable size) and growable lists (resizable at runtime).[3]
var fixed = new List.filled(3, 0); // Fixed length
var growable = <int>[1, 2, 3]; // Growable10. What is assert used for in Dart?
assert is used for debugging to test conditions that should always be true at runtime; it throws an error if false.[4]
assert(age > 0, 'Age must be positive');Intermediate Dart Interview Questions (11-20)
11. What is a class in Dart and what is its blueprint purpose?
A class in Dart is a blueprint for creating objects, defining properties and behaviors for instances.[2]
class Car {
String color;
Car(this.color);
}12. What is the default constructor in Dart?
The default constructor has no parameters and shares the class name, automatically generated if none is defined.[2][5]
13. Can you define named constructors in Dart? Provide an example.
Yes, named constructors allow multiple constructors with different names for object creation.[2]
class Person {
String name;
Person(this.name);
Person.named(String n) : name = n;
}14. What are instance variables vs local variables in Dart?
Instance variables belong to class objects and persist across methods; local variables are scoped to functions/blocks.[2]
15. What is polymorphism in Dart?
Polymorphism allows objects to share the same interface while having different implementations, enabling code reusability.[1]
16. What are the types of inheritance in Dart?
Dart supports single and multilevel inheritance where child classes derive properties from parent classes.[1]
class Animal { void eat() {} }
class Dog extends Animal { void bark() {} }17. What are named parameters in Dart?
Named parameters are passed by name, making function calls more readable and allowing optional arguments.[5]
void greet({String? name, int? age}) {
print('Hello $name, age $age');
}
greet(name: 'Alice', age: 30);18. What is method overriding in Dart?
Method overriding allows a subclass to provide a specific implementation for a parent class method using @override.[3]
class Animal {
void sound() => print('Animal sound');
}
class Cat extends Animal {
@override
void sound() => print('Meow');
}19. What is Typedef in Dart?
Typedef creates an alias for a function type, improving code readability and reusability.[4]
typedef IntList = List<int>;
typedef Calculate = int Function(int, int);20. What are conditional expressions in Dart?
Conditional expressions include ternary (condition ? expr1 : expr2) for concise if-else logic.[2]
var result = age > 18 ? 'Adult' : 'Minor';Advanced Dart Interview Questions (21-30)
21. How do you handle exceptions in Dart?
Dart uses try-catch-finally blocks to handle exceptions gracefully.[1]
try {
int result = 10 ~/ 0;
} catch (e) {
print('Error: $e');
} finally {
print('Cleanup');
}22. What is a pub in Dart?
Pub is Dart’s package manager for managing dependencies, libraries, and applications through pubspec.yaml.[1]
23. What are switch case statements in Dart?
Switch statements execute different code blocks based on matching cases, replacing multiple if-else chains.[2]
switch (day) {
case 1: print('Monday'); break;
default: print('Other day');
}24. What are the different types of constructors in Dart?
Dart supports default, parameterized, named, constant, and factory constructors for flexible object initialization.[2]
class Point {
final num x, y;
const Point(this.x, this.y);
factory Point.origin() => Point(0, 0);
}25. Explain asynchronous programming in Dart.
Dart uses Future and Stream for async operations, with async/await for readable non-blocking code.[5]
Future<int> fetchData() async {
await Future.delayed(Duration(seconds: 2));
return 42;
}26. What is the extension method in Dart?
Extensions add functionality to existing classes without modifying them.[4]
extension on String {
bool get isPalindrome => this == this.split('').reversed.join('');
}27. What are mixins in Dart and how do they differ from interfaces?
Mixins provide reusable code through implementation sharing using with, while interfaces define contracts via implements.[4]
mixin Flyable { void fly() {} }
class Bird with Flyable {}28. What are the differences between JIT and AOT compilation in Dart?
JIT compiles at runtime for faster development, while AOT compiles ahead-of-time for optimal production performance.[4]
29. Scenario: At Zoho, how would you implement a growable list to track user scores dynamically?
Use a growable List<int> and add elements as needed.
List<int> scores = [];
scores.add(95);
scores.addAll([88, 92]);
print(scores); // [95, 88, 92]30. Scenario: At Atlassian, design a parking lot system using Dart classes for different vehicle types.
Create a base Vehicle class with subclasses inheriting common properties.
abstract class Vehicle {
String get type;
int get size;
}
class Car implements Vehicle {
@override String get type => 'Car';
@override int get size => 1;
}
class ParkingLot {
List<Vehicle> slots = List.filled(100, null);
}