500+ Application Developer Interview Questions and Answers

ES6 is the newer version of JavaScript with added features like arrow functions, classes, and let/const declarations.

• ES5 is the fifth version of ECMAScript, released in 2009.

• ES6, also known as ECMAScript 2015, introduced new features like arrow functions, classes, let/const declarations, template literals, and spread/rest operators.

• ES6 also added features like default parameter values, destructuring assignments, and promises.

• ES6 modules allow for better organization and encap...read more

final, finalize and finally are three different keywords in Java with different meanings.

• final is a keyword used to declare a constant variable.

• finalize is a method used for garbage collection.

• finally is a block used in exception handling to execute code regardless of whether an exception is thrown or not.

• final and finally are not related in any way.

Semaphore and mutex are synchronization mechanisms used in multi-threaded environments.

• Semaphore allows multiple threads to access a shared resource simultaneously, while mutex allows only one thread at a time.

• Semaphore is used to control access to a pool of resources, while mutex is used to protect a single resource.

• Semaphore uses a counter to keep track of the number of available resources, while mutex uses a lock to ensure exclusive access.

• Example of semaphore: a printer t...read more

Arrange 10 coins in 4 rows of 4 coins each.

• Place 4 coins in a row and keep the remaining 6 aside.

• Place 3 coins from the remaining 6 in the next row and keep the remaining 3 aside.

• Place 2 coins from the remaining 3 in the third row and keep the remaining 1 aside.

• Place the last coin in the fourth row along with the remaining 1 coin from step 3.

• The final arrangement will have 4 rows with 4 coins each.

Handle git merge conflicts by resolving conflicts manually or using tools like git mergetool.

• Manually resolve conflicts by editing the conflicting files in text editor

• Use 'git status' to see which files have conflicts

• Use 'git diff' to see the conflicting changes

• Use 'git mergetool' to open a visual merge tool to resolve conflicts

• After resolving conflicts, add the changes and commit the merge

findElement() returns the first matching element on the web page, while findElements() returns a list of all matching elements.

• findElement() returns a single WebElement matching the locator provided.

• findElements() returns a list of WebElements matching the locator provided.

• If no elements are found, findElement() will throw a NoSuchElementException, while findElements() will return an empty list.

I will prioritize urgent client or user pings and respond promptly to address their needs.

• Prioritize urgent client or user pings over non-urgent ones

• Respond promptly to address their needs

• Communicate with the client or user to understand the issue and provide assistance

• Document the issue and resolution for future reference

Count the frequency of each alphabet in a string.

• Iterate through the string and count the occurrence of each alphabet using a dictionary or array.

• Convert the string to lowercase or uppercase to avoid case sensitivity.

• Exclude non-alphabetic characters using regular expressions.

• Consider using built-in functions or libraries for efficiency.

• Handle edge cases such as empty strings or strings with no alphabetic characters.

Python is a popular programming language used for web development. Django and Flask are common frameworks for web development in Python.

• Python is a versatile programming language known for its simplicity and readability.

• Django is a high-level Python web framework that encourages rapid development and clean, pragmatic design.

• Flask is a lightweight WSGI web application framework that is easy to learn and quick to get started with.

• Both Django and Flask provide tools and librarie...read more

Sub categories in apps are smaller categories within a main category that help organize and navigate content more efficiently.

• Sub categories help users easily find specific content within an app

• They can be used to group similar features or functions together

• Examples include sub categories like 'Settings', 'Notifications', 'Profile' within a main category like 'Account'

OOPS stands for Object-Oriented Programming System. It is a programming paradigm based on the concept of objects.

• OOPS focuses on creating objects that contain data in the form of fields (attributes) and code in the form of procedures (methods).

• Encapsulation, inheritance, and polymorphism are key principles of OOPS.

• Encapsulation refers to the bundling of data and methods that operate on the data into a single unit (object).

• Inheritance allows a class to inherit properties and b...read more

Frontend is the part of a website or application that users interact with, while backend is the part that handles the behind-the-scenes functionality.

• Frontend is responsible for the user interface and user experience.

• Backend is responsible for server-side logic, database operations, and other behind-the-scenes tasks.

• Frontend technologies include HTML, CSS, and JavaScript.

• Backend technologies include languages like Java, Python, and frameworks like Node.js.

• Examples: Frontend -...read more

Indexes used include bitmap and btree. Bitmap index is used for low cardinality columns, while btree index is used for high cardinality columns.

• Bitmap index is efficient for low cardinality columns with few distinct values

• Btree index is efficient for high cardinality columns with many distinct values

• Bitmap index uses bitmaps to represent the presence of a value in a column

• Btree index is a balanced tree structure that allows for fast searching and retrieval of data

HTTP status codes indicate the status of a web request.

• 1xx - Informational

• 2xx - Success

• 3xx - Redirection

• 4xx - Client Error

• 5xx - Server Error

• Examples: 200 OK, 404 Not Found, 500 Internal Server Error

Function overloading is when multiple functions have the same name but different parameters. Polymorphism is the ability of an object to take on many forms.

• Function overloading allows multiple functions with the same name but different parameters to be defined.

• Polymorphism allows objects of different classes to be treated as objects of a common superclass.

• Function overloading is resolved at compile-time, while polymorphism is resolved at runtime.

Windows and Linux are two different operating systems. I prefer Linux because of its open-source nature and flexibility.

• Windows is a proprietary operating system developed by Microsoft, while Linux is an open-source operating system.

• Linux is more flexible and customizable than Windows.

• Linux is known for its stability and security.

• Windows is more user-friendly and has better compatibility with software.

• Examples of Linux distributions include Ubuntu, Fedora, and CentOS, while e...read more

Heap sorting is a comparison-based sorting algorithm that divides the input into a sorted and an unsorted region, while insertion sorting builds the final sorted array one item at a time.

• Heap sorting has a worst-case time complexity of O(n log n), while insertion sorting has a worst-case time complexity of O(n^2)

• Heap sorting is not an in-place sorting algorithm, while insertion sorting is

• Heap sorting is more efficient for larger datasets, while insertion sorting is more effic...read more

The source code for doubly linked list is a data structure that contains nodes with pointers to the previous and next nodes.

• Declare a node struct with data, prev, and next pointers

• Create a head and tail pointer to the first and last nodes

• Implement functions to add, remove, and traverse nodes

Different Linux OS have different features, package managers, and user interfaces.

• Linux distributions have different package managers, such as apt, yum, and pacman.

• Some distributions are designed for specific purposes, such as Kali Linux for penetration testing.

• User interfaces can vary greatly, with some distributions using GNOME, KDE, or Xfce.

• Some distributions are more lightweight and optimized for older hardware, such as Lubuntu or Puppy Linux.

React lifecycle consists of three main stages: Mounting, Updating, and Unmounting.

• Mounting: Component is created and inserted into the DOM.

• Updating: Component is re-rendered due to changes in props or state.

• Unmounting: Component is removed from the DOM.

• Examples: componentDidMount() is called during Mounting stage, componentDidUpdate() during Updating stage, and componentWillUnmount() during Unmounting stage.

I use various git commands like git clone, git pull, git push, git commit, git branch, git merge, etc.

• git clone - to clone a repository from a remote server

• git pull - to fetch and merge changes from a remote repository

• git push - to push changes to a remote repository

• git commit - to save changes to the local repository

• git branch - to create, list, delete, or manipulate branches

• git merge - to merge changes from one branch to another

Talend is an ETL tool used for data integration. Jobs are workflows created in Talend to perform specific tasks. Components are pre-built functions used in jobs.

• Jobs are created in Talend to perform specific tasks such as data extraction, transformation, and loading.

• Components are pre-built functions that can be used in jobs to perform specific actions such as reading data from a file or database, transforming data, and writing data to a file or database.

• Talend provides a wid...read more

Talend is popular due to its open-source nature, ease of use, and ability to integrate with various systems.

• Talend is open-source, making it accessible to a wide range of users.

• It has a user-friendly interface, allowing developers to easily create and manage data integration workflows.

• Talend can integrate with various systems, including cloud-based platforms like AWS and Azure.

• It offers a wide range of connectors and components, making it versatile and adaptable to different ...read more

Activities include ETL processes, data migration, data synchronization, and data replication.

• ETL (Extract, Transform, Load) processes

• Data migration

• Data synchronization

• Data replication

Restful service process flow involves client sending requests to server, which responds with data in a standardized format.

• Client sends HTTP request to server

• Server processes request and sends back HTTP response

• Response is in a standardized format such as JSON or XML

• Client can then use the response data as needed

Open source software has advantages like cost-effectiveness, flexibility, and community support, but also has disadvantages like security risks and lack of accountability.

• Advantages: cost-effectiveness, flexibility, community support

• Disadvantages: security risks, lack of accountability

• Examples: Linux, Apache, MySQL are popular open source software

• Open source software allows for customization and collaboration

• However, lack of accountability can lead to slower bug fixes and sec...read more

Inheritance is a way to create new classes based on existing classes. Polymorphism allows objects of different classes to be treated as if they were of the same class.

• Inheritance allows a child class to inherit properties and methods from a parent class.

• Polymorphism allows a method to be used with objects of different classes that share a common interface.

• Example of inheritance: A car class can be inherited by a sports car class, which can inherit the properties and methods o...read more

Double linked list has pointers to both next and previous nodes, while single linked list only has pointer to next node.

• Double linked list allows for traversal in both directions, while single linked list only allows traversal in one direction.

• Insertions and deletions are more efficient in double linked list as compared to single linked list.

• Double linked list requires more memory as compared to single linked list due to the additional pointer for previous node.

SpringBootAnnotation is used to enable Spring Boot features in a Java application. @Controller is used for MVC pattern, @RestController is used for RESTful web services.

• SpringBootAnnotation is used to enable Spring Boot features like auto-configuration, component scanning, etc.

• @Controller is used for MVC pattern to handle web requests and return a view, while @RestController is used for RESTful web services to return data.

• @Controller is a specialization of @Component annotati...read more

Stream API in Java provides a way to process collections of objects in a functional style.

• Stream API allows for easy manipulation of collections using functional programming concepts like map, filter, and reduce.

• Example: List<String> names = Arrays.asList("Alice", "Bob", "Charlie"); names.stream().filter(name -> name.startsWith("A")).forEach(System.out::println);

• Lambda expressions can be used with Stream API to define behavior to be applied to each element in the stream.

• Examp...read more

Abend with -911 is a deadlock error. Identify the resources causing the deadlock and release them.

• Check the application logs for more information on the error.

• Identify the resources involved in the deadlock using system logs or monitoring tools.

• Release the resources causing the deadlock by terminating the associated processes or transactions.

• Modify the application code to prevent future deadlocks.

Domain is a collection of data elements, select statement retrieves specific data, value tables store data values, BDC is used for data transfer, smart forms are advanced form creation tools.

• Domain is a collection of data elements defining the characteristics of a field.

• Select statement retrieves specific data from a database table based on specified criteria.

• Select all statement retrieves all data from a database table.

• Value tables store data values for selection in dropdown...read more

Use Python to print the last 10 dates from today in the specified format.

• Get the current date using the datetime module in Python.

• Loop through the last 10 days using a for loop and timedelta to subtract one day at a time.

• Format each date as 'day month year' using strftime method.

• Store each formatted date in an array of strings.

Dependency injection is a design pattern where components are given their dependencies rather than creating them internally.

• Allows for easier testing by providing mock dependencies

• Promotes loose coupling between components

• Improves code reusability and maintainability

• Examples: Constructor injection, Setter injection, Interface injection

Windows OS is a proprietary operating system developed by Microsoft while Ubuntu is a free and open-source operating system based on Linux.

• Windows OS is more widely used in desktops and laptops while Ubuntu is popular among developers and servers.

• Windows OS has a graphical user interface (GUI) while Ubuntu can be used with or without a GUI.

• Windows OS has a larger selection of software and games available while Ubuntu has a smaller but growing selection.

• Windows OS is more vuln...read more

Procedures do not return a value, while functions return a value.

• Procedures are used to perform an action, while functions are used to calculate and return a value.

• Functions must return a value, while procedures do not have a return statement.

• Functions can be called from within SQL statements, while procedures cannot.

• Example: Procedure - void PrintMessage(string message) { Console.WriteLine(message); }

• Example: Function - int AddNumbers(int a, int b) { return a + b; }

Use SQL query to retrieve employees with birthdays and send emails to them.

• Write a SQL query to retrieve employees with birthdays from the database

• Use a programming language like Python to send emails to the retrieved employees

• Ensure the email content includes birthday wishes and any relevant information

To delete nth node in a linked list, we need to traverse to the (n-1)th node and change its next pointer to (n+1)th node.

• Traverse to (n-1)th node and change its next pointer to (n+1)th node

• Handle edge cases like deleting the first node or deleting the last node

• Free the memory of the deleted node

Laravel is a popular PHP framework known for its elegant syntax and powerful features. Update query in SQL is used to modify existing records in a database.

• Laravel provides a convenient way to interact with databases using Eloquent ORM.

• Update query in SQL is used to modify existing records based on specified conditions.

• In Laravel, you can use the update method on Eloquent models to update records in the database.

• Example: User::where('id', 1)->update(['name' => 'John Doe']);

To get the assignment details of the operator for a specific access group in Pega, you can use the OOTB activity 'pxRetrieveAssignmentsForOperator'.

• Use the OOTB activity 'pxRetrieveAssignmentsForOperator' to retrieve assignment details for a specific operator and access group.

• Pass the operator ID and access group name as parameters to the activity.

• The activity will return a list of assignments for the specified operator and access group.

To resolve performance issues while consuming details from API in Pega, optimize API calls, use caching, and analyze network and server performance.

• Optimize API calls by reducing unnecessary data retrieval and processing

• Implement caching mechanisms to store frequently accessed data locally

• Analyze network and server performance to identify bottlenecks and optimize accordingly

Integrating multiple legacy systems with modern cloud-based applications.

• Developing custom APIs to bridge the gap between different systems

• Handling data transformation and mapping between incompatible formats

• Ensuring data security and compliance during integration

• Resolving performance issues and optimizing data flow

• Collaborating with various teams to understand system requirements and constraints

Functional components are simpler, more concise, easier to read, and promote reusability.

• Functional components are simpler and more concise compared to class components.

• Functional components use less code and are easier to read and maintain.

• Functional components promote reusability through the use of hooks.

• Functional components are easier to test and debug.

• Functional components support the use of React hooks for managing state and side effects.

Constructor is a method used to create and initialize an object, while ngOnInit is a lifecycle hook used in Angular to initialize a component.

• Constructor is called when an object is created, while ngOnInit is called after the component is initialized.

• Constructor is used to set default values and initialize properties, while ngOnInit is used to perform additional initialization tasks.

• Constructor is defined in the class, while ngOnInit is a lifecycle hook provided by Angular.

• Ex...read more

Abstract class can have both abstract and non-abstract methods, while Interface can only have abstract methods.

• Abstract class can have constructors, fields, and methods, while Interface cannot have any implementation.

• A class can extend only one Abstract class but can implement multiple Interfaces.

• Abstract classes are used to define a common behavior for subclasses, while Interfaces are used to define a contract for classes to implement.

• Abstract classes can have access modifie...read more

Various memory available in an OS include primary memory (RAM), secondary memory (hard disk), cache memory, and virtual memory.

• Primary memory (RAM) is used to store data and instructions that are currently being used by the CPU.

• Secondary memory (hard disk) is used for long-term storage of data and programs.

• Cache memory is a small, high-speed memory that stores frequently accessed data to improve CPU performance.

• Virtual memory is a technique that allows the OS to use a portion...read more

Data passing between view controllers can be done using properties, delegates, notifications, segues, or user defaults.

• Use properties to directly pass data between view controllers

• Implement delegates to establish communication between view controllers

• Post notifications to broadcast data to multiple view controllers

• Pass data through segues when transitioning between view controllers

• Store data in user defaults for persistent data sharing