SwiftWIN Technologies Interview Questions and Answers

DB connection should be opened in onCreate() and closed in onDestroy() method.

• Open DB connection in onCreate() method.

• Close DB connection in onDestroy() method.

• Avoid opening and closing DB connection frequently.

• Use SQLiteOpenHelper class to manage DB connection.

OOPs concepts are fundamental to object-oriented programming. They include inheritance, encapsulation, abstraction, and polymorphism.

• Inheritance: A child class can inherit properties and methods from a parent class. Example: A Car class can inherit from a Vehicle class.

• Encapsulation: Hiding implementation details and exposing only necessary information. Example: A BankAccount class can hide the account balance.

• Abstract...read more

LINQ allows for easy querying of collections, including performing left joins to combine data from different sources.

• Use 'GroupJoin' to perform a left join in LINQ.

• Example: var result = from a in tableA join b in tableB on a.Id equals b.AId into temp from b in temp.DefaultIfEmpty() select new { a, b };

• The 'DefaultIfEmpty()' method ensures that even if there are no matches in tableB, records from tableA are still includ...read more

Authentication is the process of verifying the identity of a user, while authorization is the process of granting access to specific resources.

• Authentication confirms the user's identity through credentials such as username and password.

• Authorization determines what resources the user can access based on their role or permissions.

• Authentication precedes authorization in the security process.

• Examples of authentication i...read more

Constructors are special methods used to initialize objects in a class.

• Default constructor: no arguments

• Parameterized constructor: one or more arguments

• Copy constructor: creates a new object as a copy of an existing object

• Static constructor: initializes static variables

• Private constructor: restricts object creation outside the class

Index in SQL Server is used to improve query performance. There are different types of indexes.

• Clustered index: sorts and stores data rows in the table based on their key values

• Non-clustered index: contains a separate structure with the indexed columns and a pointer to the data rows

• Unique index: ensures that the indexed columns contain unique values

• Filtered index: indexes a subset of data rows based on a filter predica...read more

Developed a web application for a retail company to manage their inventory and sales.

• Used React.js for the front-end and Node.js for the back-end

• Implemented a database schema using MongoDB

• Integrated Stripe API for payment processing

• Implemented user authentication and authorization using JWT

• Optimized application performance by implementing caching and lazy loading

ref is used for passing reference types by reference, out is used for returning values by reference.

• Use ref when you want to modify the value of the parameter inside the method

• Use out when you want to return multiple values from a method

• ref requires the variable to be initialized before passing it to the method, out does not

• ref can be used with both value and reference types, out can only be used with reference types

Middleware in .NET Core is a pipeline of components that handle requests and responses.

• Middleware is added to the pipeline using the Use() method in Startup.cs

• Middleware can modify the request or response, or pass it on to the next component in the pipeline

• Examples of middleware include authentication, logging, and error handling