Here are the most common asked Interview Questions for Dart:
1. What is Dart?
Ans: Dart is the high-level programming level that helps to build applications which is created by Google.
2. Explain the main features of Dart.
Ans: As Dart is the OOP language, it has all the features of OOP such as Inheritance, classes and objects, Polymorphism, Abstraction and Encapsulation.
3. How do you declare variables in Dart?
Ans: Dart variables can be declared using keyword var followed by varibale_name.
4. What are the different data types available in Dart?
Ans: There are different types of data types available in Dart, they are:
int, double, num, string, boolean, list, map, set, and dynamic.
5. How do you write a for loop in Dart?
Ans: For loop in Dart is written as:
for(initialization; condition; update){
//statements
}
6. How do you write an if-else statement in Dart?
Ans: You can write if-else statement as:
if (condition){
//statements
}else{
//statements
}
7. What is a List in Dart? How do you create and manipulate a List?
Ans: A list in Dart is an ordered collection of objects that allows developers to store and manipulate data.
List<data_type> list_name = [value1, value2, value3, ...];
you can manipulate list through different list of methods
8. What is a Map in Dart? How do you create and manipulate a Map?
Ans: A Map in Dart is a dart collections that are similar to json with a key and value.
Map<key_datatype, value_datatype> mapName = { key1 : value1, key2 : value2};
Here is more detailed about manupulation of Map in dart.
9. How do you define a function in Dart?
Ans: Functions are the buidling blocks of readable, maintainable, and reusable code. Same as other languages they are defined first and called.
10. What is the difference between const and final in Dart?
Ans: Const and final are keywords in dart that define to used to declare varibale in compile time and varibale that is declared as final (read only) respectively.
11. How do you handle exceptions in Dart?
Ans; Exceptions in dart are handle by try, catch and finally blocks.
12. What are async and await in Dart?
Ans: Async is used to specify that a function, method or block of code is asynchronous where as await is Used to suspend execution until an asynchronous operation completes.
13. What is a Set in Dart? How do you create and manipulate a Set?
Ans: A Set in Dart is the fundamental data structures which represents a collection of objects in which each object can occur only once..
Set<datatype> var_name = {};
Here is more detailed about manupulation of Set in dart.
14. Explain the use of assert in Dart.
Ans: Assert is used as debugging that helps to ensure that a condition is true, if false error is thrown.
15. What is a Future in Dart? How do you work with futures?
Ans: Future is used in asynchronous programming in dart where it represents a potential value or error that will be available at some time in the future. you can work with futures in asynchronous programming when called , which uses ’then’, ‘catchError’ and ‘whenComplete’.
16. What are Stream and StreamController in Dart?
Ans: A Stream is a sequences of asynchronous events that are particularly useful for handling events like user inputs, data from network requests, and real-time updates. A StreamController is a class that provides a way to create and manage streams of data.
17. How do you write a switch statement in Dart?
Ans: Switch is a flow control that evaluates expressions and matches the expression value.
switch(variable_expression){
case constant_expr1:{
//statements;
}
break;
case constant_expr2:{
//statements;
}
break;
default:{
//statements;
}
break;
}
18. What is a String in Dart? How do you manipulate strings?
Ans: String in Dart is a sequence of characters enclosed with a single quotes or double quotes. They can be manipulate through different ways like conctatination, reversing, accessing characters, substring, changing case etc.
19. What are the main types of operators in Dart?
Ans: The main types of operators in Dart are: Arithmetic Operators, Equality and relational Operators, Type test Operators, Assignment Operators, Logical Operators and Bitwise and shift Operators.
20. Explain the concept of null safety in Dart.
Ans: Null Safety is the safety enforing to prevent errors that result from unintentional access of variables set to null. Non-nullable by default and Fully sound are the two null safety principles in Dart.
21. How do you create a class in Dart?
Ans: In Dart class can be created by using class keyword followed by class_name.
22. What is inheritance in Dart? How do you implement it?
Ans: Inheritance is the process of passing on properties from one generation to another. For example, a child inherits the properties of his/her parents and grandparents which continues this from generation to generation.
Inheritance can be implemented by using keyword “extends” using the properties of the parent class to the child.
23. What are abstract classes in Dart? When do you use them?
Ans: Abstract classes are classes that contain one or more abstract methods. Abstraction of a class is done by using the abstract keyword.
25. How do you define a constructor in Dart?
Ans: A constructor is a special method that is used to initialize objects. The name of the constructor is the same as the name of the class. Constructor can be defined when the class name is equal to the method name . Like class Constructor and method void Constructor().
26. What is polymorphism in Dart? How do you achieve it?
Ans: Polymorphism is a feature of OOP which means that we can perform a single action in different ways. Polymorphsim can be achieve through method overriding .
27. Explain the use of generics in Dart.
Ans: Generics in Dart provide a way to create classes, methods, and functions that can operate on different types while providing type safety.
28. How do you implement interfaces in Dart?
Ans: In Dart, interfaces are implemented using classes. Every class implicitly defines an interface that other classes can implement. To implement an interface, you use the implements keyword. This allows a class to promise that it will provide concrete implementations for the methods and properties defined in the interface. Interfaces are often defined using abstract classes.
29. What is an enumeration (enum) in Dart? How do you use it?
Ans: In Dart, an enumeration, commonly known as an enum, is a special type that allows you to define a collection of named constant values. Enums are used to represent a fixed set of related values in a type-safe way. It is used to declare an enumerated (unchangeable) type.
30. What is the purpose of the factory keyword in Dart?
Ans: The “factory” keyword id used to define a factory constructor. A factory constructor is a constructor that can return an instance of the class, an instance of a subtype, or even an instance of a previously created object.
31. Explain the difference between synchronous and asynchronous programming in Dart.
Ans: synchronous and Asynchronous programming are different from each other because one executes sequentially where as other is executed out of order respectively. Synchronous block the main thread whereas Asynchronous does not block the main thread.
32. How do you create and use a Stream in Dart?
Ans: For Asynchronous programming which uses callback functions. stream can be created in three ways: Creating stream form scratch by using an ‘async’ function, Creating a stream by using a “StreamController, Transforming an existing streams.
33. What is the Iterable class in Dart?
Ans: In Dart, the Iterable class represents a collection of elements that can be iterated, meaning you can traverse through the elements one by one. It is a core part of Dart’s collection library and serves as the base class for collections like List and Set.
34. How do you create and use custom annotations in Dart?
Ans: Annotations are metadata that can be applied to classes, methods, fields, and other elements in your code. To create a annotation we should define the annotation class and apply the custom annotation to classes, methods, or other elements using @ symbol.
35. What is the Isolate class in Dart? How do you use it?
Ans: An Isolate is a fundamental unit of concurrency that allows for parallel execution of code. Each isolate runs independently, with its own memory space, and communicates with other isolates via message passing. 36. Explain the concept of reflection in Dart.
Ans: Reflection in Dart allows you to inspect and interact with the structure and metadata of your code at runtime.Dart’s reflection can still access annotations using the dart:mirrors library.
37. How do you serialize and deserialize JSON in Dart?
Ans: Serialization is the process of converting a Dart object into a JSON string. This is typically done using the jsonEncode function from the dart:convert library. Deserialization is the process of converting a JSON string into a Dart object. This is done using the jsonDecode function from the dart:convert library.
38. What are extension methods in Dart? Ans: Extension methods in Dart provide a way to add new functionality to existing classes without modifying their source code. They allow you to extend a class with new methods, getters, and setters in a modular and reusable way. To define an extension, you use the extension keyword followed by the name of the extension and the type you want to extend
39. How do you perform file I/O in Dart?
Ans: File I/O in Dart can be performed like any other file I/O involving reading from and writing to files. Dart provides the dart:io library for this purpose, which includes classes and methods to handle file operations. read(), write(), delete(), append() are the mode for file input output.
40. What is dependency injection? How do you implement it in Dart?
Ans: Dependency Injection (DI) is a design pattern used to manage and provide dependencies in an application. It promotes loose coupling and enhances the flexibility and testability of code by separating the creation of an object from its usage. Dart does not have a built-in dependency injection framework, but you can implement DI in various ways: Manual Dependency Injection and Using a Dependency Injection Framework