80+ QBurst Technologies Interview Questions and Answers

Yes, it is possible to work with multiple threads in core data.

• Use NSManagedObjectContextConcurrencyType to specify concurrency type

• Create a separate managed object context for each thread

• Use performBlock or performBlockAndWait to execute tasks on the correct context

• Merge changes from other contexts using NSManagedObjectContextDidSaveNotification

XPath is a language used to locate elements in an XML document. Yes, we can find web elements using XPath.

• XPath is used to navigate through elements and attributes in an XML document

• It can also be used to locate elements in HTML documents

• XPath expressions can be used with Selenium WebDriver to locate web elements

• Example: driver.findElement(By.xpath("//input[@id='username']"));

As a tester, I faced challenges in identifying and reproducing defects. I overcame it by improving my communication and collaboration skills with the development team.

• Identifying and reproducing defects was a challenge

• Improved communication and collaboration with the development team

• Used tools like JIRA and Trello to track defects and progress

• Developed a better understanding of the product and its features

• Created detailed test cases and test plans to ensure comprehensive test...read more

The optimal algorithm for finding common elements in two arrays is using a hash table.

• Create a hash table for one of the arrays.

• Iterate through the other array and check if each element exists in the hash table.

• If it does, add it to the result array.

• Time complexity is O(n) and space complexity is O(n).

I have used JIRA and Bugzilla for defect tracking. Parameters include severity, priority, steps to reproduce, and expected vs actual results.

• Defect tracking tools used: JIRA and Bugzilla

• Parameters of defect reporting: severity, priority, steps to reproduce, expected vs actual results

• Severity: impact of the defect on the system

• Priority: importance of fixing the defect

• Steps to reproduce: detailed instructions on how to replicate the defect

• Expected vs actual results: what was ex...read more

We use a combination of manual and automated testing to perform cross browser testing.

• We identify the most commonly used browsers by our users and test on those first.

• We use automated testing tools like Selenium to test on multiple browsers simultaneously.

• We also perform manual testing on each browser to ensure compatibility.

• We document any issues found and prioritize them based on severity.

• We regularly update our testing process to include new browsers and versions.

Memory leaks occur when a program fails to release memory that is no longer needed.

• Memory leaks can happen due to programming errors such as not freeing allocated memory

• Leaked memory can accumulate over time and cause the program to crash or slow down

• Memory leaks can be detected using tools such as valgrind or by analyzing the program's behavior

• Examples of memory leaks include forgetting to free memory allocated for a variable or not closing a file after reading from it

UAT testing is User Acceptance Testing, where end-users test the software to ensure it meets their requirements.

• UAT testing is the final phase of testing before the software is released to the end-users.

• It is performed by end-users or a representative group of end-users.

• The goal of UAT testing is to ensure that the software meets the business requirements and is fit for purpose.

• UAT testing can be performed manually or using automation tools.

• Examples of UAT testing include tes...read more

API testing is performed using a combination of manual and automated testing techniques.

• We use tools like Postman and SoapUI for API testing

• We create test cases based on API documentation and requirements

• We test for functionality, performance, security, and error handling

• We use mock servers to simulate API responses

• We perform both positive and negative testing

• We use automation scripts to perform regression testing

• We collaborate with developers to ensure API changes are tested...read more

To get data from a file in Selenium, we can use Java IO classes and read the file content.

• Create a File object with the file path

• Create a FileReader object with the File object

• Create a BufferedReader object with the FileReader object

• Use the BufferedReader object to read the file content line by line

• Close the BufferedReader object

Performance testing is the process of evaluating the speed, responsiveness, stability, and scalability of a software application.

• It involves simulating real-world scenarios to measure the application's performance under different loads.

• JMeter is a popular open-source tool used for performance testing.

• It can be used to test web applications, APIs, and databases.

• JMeter allows testers to create and execute test plans, generate reports, and analyze results.

• Performance testing hel...read more

Test case can be executed multiple times using automation tools or by manually running the test case.

• Use automation tools like Selenium or Appium to execute test cases multiple times.

• Create a loop in the automation script to execute the test case multiple times.

• Manually execute the test case multiple times by following the steps in the test case document.

• Use data-driven testing to execute the same test case with different input values.

• Use random testing to execute the test ca...read more

Mobile testing is performed by creating test cases, selecting devices, and using automation tools.

• Create test cases based on requirements and user scenarios

• Select devices based on market share and user demographics

• Use automation tools like Appium or Selenium for functional and regression testing

• Perform manual testing for usability, accessibility, and compatibility

• Test for network connectivity, battery usage, and performance

• Verify app store submission guidelines and security s...read more

Our current sprint duration is 2 weeks.

• Our team follows the Agile methodology and we have adopted a 2-week sprint cycle.

• We have found that this duration allows us to deliver high-quality software within a reasonable timeframe.

• During each sprint, we focus on completing a set of user stories and addressing any bugs or issues that arise.

• At the end of each sprint, we conduct a retrospective to identify areas for improvement and make adjustments for the next sprint.

A test case can be excluded from execution by using tags or annotations.

• Add a tag or annotation to the test case with a specific value

• Configure the test runner to exclude test cases with that tag or annotation

• Use conditional statements in the test code to skip the test case based on certain conditions

I test mobile applications by performing functional, usability, performance, and security testing.

• I start by identifying the requirements and creating test cases.

• I perform functional testing to ensure the app meets the requirements.

• I test the usability of the app by checking the user interface and user experience.

• I perform performance testing to check the app's speed, stability, and scalability.

• I test the security of the app by checking for vulnerabilities and ensuring data p...read more

Alpha testing and beta testing are two types of software testing performed before releasing the software to the public.

• Alpha testing is performed by the developers in-house, before releasing the software to external testers.

• Beta testing is performed by external testers, after the software has been released to a limited audience.

• Alpha testing is focused on identifying bugs and issues in the software, while beta testing is focused on gathering feedback from users.

• Alpha testing ...read more

Postman tool has various variables like environment, global, collection, local, etc.

• Environment variables: Used to store values that can be used across requests in a specific environment

• Global variables: Used to store values that can be used across requests in all environments

• Collection variables: Used to store values that can be used across requests in a specific collection

• Local variables: Used to store values that can be used within a single request

• Data variables: Used to s...read more

Status codes are numerical codes that indicate the status of a HTTP request/response.

• Status codes are grouped into 5 categories: informational, success, redirection, client error, and server error.

• Informational codes (1xx) indicate that the request was received and understood.

• Success codes (2xx) indicate that the request was successfully received, understood, and accepted.

• Redirection codes (3xx) indicate that further action needs to be taken in order to complete the request.

• C...read more

Count the occurrence of each word in a given string and store it in a map.

• Split the string into words using whitespace as delimiter

• Create a map to store the word count

• Iterate through the words and update the count in the map

• Return the map

Network latency testing is the process of measuring the delay in data transmission over a network.

• It involves sending data packets from one point to another and measuring the time taken for the response to be received.

• Latency can be affected by factors such as network congestion, distance, and hardware limitations.

• Tools such as ping and traceroute can be used to perform network latency testing.

• The results of network latency testing can help identify areas for improvement in n...read more

List is an ordered collection of elements while Set is an unordered collection of unique elements.

• List allows duplicate elements while Set does not.

• List maintains the order of elements while Set does not.

• List is implemented using an array while Set is implemented using a hash table.

• Example: List - [1, 2, 3, 3, 4], Set - {1, 2, 3, 4}

Upgradation testing is the process of testing an upgraded version of software or hardware to ensure its compatibility and functionality.

• It involves testing the upgraded version of software or hardware

• The purpose is to ensure compatibility and functionality

• It includes testing for data migration, backward compatibility, and performance

• Examples include upgrading an operating system, upgrading a database management system, etc.

Input a number and print all odd numbers up to one in decreasing order.

• Create a loop to iterate from the input number down to 1

• Check if the current number is odd before printing it

• Decrement the current number in each iteration

Implementing random function without in-built random()

• Use current time as seed value

• Generate a sequence of numbers using a mathematical formula

• Use external sources of randomness like atmospheric noise

• Implement a linear congruential generator

• Use a hash function to generate pseudo-random numbers

Class not found and no class definition found exception occurs when a required class is not found during runtime.

• This exception occurs when the JVM tries to load a class but cannot find it in the classpath.

• It can happen if the class is missing from the project dependencies or if the classpath is not properly configured.

• Check if the class is present in the correct package and if it is included in the project dependencies.

• Verify the classpath settings and ensure that all requir...read more

Pseudo code for basic java programs

• Declare variables and assign values

• Write conditional statements

• Use loops for repetitive tasks

• Create functions for reusable code

• Use arrays and collections for storing data

defer in Go is used to delay the execution of a function until the surrounding function returns.

• Defer is used to ensure that a function call is performed at the end of the surrounding function, regardless of where the defer statement is located.

• If there are multiple defers in a function, they will be executed in Last In, First Out (LIFO) order.

• Example: func exampleFunc() { defer fmt.Println('First defer'); defer fmt.Println('Second defer'); } // Output: Second defer First def...read more

A braking system works by converting kinetic energy into heat energy through friction to slow down or stop a vehicle.

• When the brake pedal is pressed, hydraulic fluid is sent to the brake calipers or drums

• The calipers squeeze the brake pads against the rotor, creating friction and slowing down the vehicle

• In disc brakes, the rotor is attached to the wheel, while in drum brakes, the brake shoes press against the inside of the drum

• The friction between the pads and rotor/drum conv...read more

Use two pointers to swap 0's and 1's in a single pass.

• Initialize two pointers, one at the beginning and one at the end of the array.

• Move the first pointer towards the end and the second pointer towards the beginning, swapping 0's and 1's as needed.

• Continue until the two pointers meet in the middle.

Cut the cake horizontally into two halves, then cut each half vertically into four equal parts.

• Cut the cake horizontally into two halves

• Make two vertical cuts through each half to get four equal parts

• Repeat the same process for the other half of the cake

Abstract class is a class that cannot be instantiated while Interface is a contract that a class can implement.

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

• A class can implement multiple interfaces but can only inherit from one abstract class.

• Abstract class can have constructors while Interface cannot.

• Abstract class can have instance variables while Interface cannot.

• Example of abstract class: Animal (abstract me...read more

Difference between Drop, Delete and Truncate commands in SQL

• DROP command deletes the entire table along with its structure

• DELETE command deletes specific rows from the table

• TRUNCATE command deletes all the rows from the table but keeps the structure intact

• DROP and TRUNCATE cannot be rolled back, but DELETE can be rolled back

A simple todo app with add and remove option using useState, useEffect hook and persistent storage.

• Create a functional component with a form to add new tasks

• Use useState hook to manage the list of tasks

• Use useEffect hook to save and retrieve data from local storage

• Add a button to remove tasks from the list

• Style the app with CSS or a UI library like Material-UI

Closures are useful for creating private variables and functions. Event loop is a mechanism for handling asynchronous operations.

• Closures allow for encapsulation and data privacy in JavaScript.

• They can be used to create private variables and functions.

• Event loop is a mechanism for handling asynchronous operations in JavaScript.

• It allows for non-blocking I/O operations and prevents the UI from freezing.

• The event loop continuously checks the call stack and the message queue for...read more

Microcontrollers are integrated circuits designed for specific tasks with built-in memory and peripherals, while microprocessors are general-purpose CPUs without built-in memory or peripherals.

• Microcontrollers are typically used in embedded systems for specific tasks like controlling a microwave oven or a washing machine.

• Microprocessors are used in general-purpose computing devices like laptops, desktops, and servers.

• Microcontrollers have built-in memory and peripherals like ...read more

Java 8 introduced several new features including lambda expressions, streams, and default methods.

• Lambda expressions for functional programming

• Streams for efficient processing of large data sets

• Default methods to add new functionality to interfaces

• Date and Time API for improved handling of date and time

• Nashorn JavaScript engine for improved performance

• Parallel array sorting for faster sorting of large arrays

Java code to filter even numbers from a list and store the square of those in another list

• Create two ArrayLists to store the original list and the squared even numbers list

• Iterate through the original list and check if each number is even

• If the number is even, square it and add it to the squared even numbers list

Singleton class is a class that allows only one instance of itself to be created and provides a global point of access to it.

• Singleton class restricts the instantiation of a class to a single object.

• It is used when only one instance of a class is required to control actions throughout the system.

• The Singleton pattern is implemented by creating a class with a method that creates a new instance of the class if one doesn't exist and returns it if it does.

• The constructor of the S...read more

Merkle root is a hash value generated by hashing all the transactions in a block in a blockchain.

• Merkle root is used to efficiently verify the integrity of the transactions in a block.

• It is calculated by hashing the individual transactions in the block, then pairing and hashing those results until a single hash remains.

• Any change in the transactions will result in a different merkle root.

• Example: In a block containing transactions A, B, C, and D, the merkle root would be the ...read more

To test a messaging app, I would perform functional, usability, performance, and security testing.

• Functional testing to ensure all features work as intended

• Usability testing to ensure the app is user-friendly

• Performance testing to ensure the app can handle high traffic

• Security testing to ensure user data is protected

• Test different scenarios such as sending messages with emojis, attachments, and different file types

• Test the app on different devices and operating systems

• Test th...read more

Mechanical engineers play a crucial role in designing by applying principles of physics and materials science to create functional and efficient products.

• Mechanical engineers work on the structural design of products, ensuring they are strong and durable.

• They also focus on the mechanical systems within a product, such as engines or HVAC systems.

• Mechanical engineers collaborate with other engineers, such as electrical and software engineers, to integrate different components i...read more

Jenkins achieves continuous integration through automated builds, tests, and deployments.

• Jenkins automatically builds and tests code changes as they are committed to the repository.

• It integrates with various tools and plugins to automate the entire software development process.

• Jenkins can be configured to trigger builds and tests based on specific events, such as code commits or pull requests.

• It provides real-time feedback on build and test results, allowing developers to qui...read more

Stress is a psychological response to external pressures, while pressure is the external force or demand placed on an individual.

• Stress is the body's response to a perceived threat, while pressure is the external force or demand placed on an individual.

• Stress can be caused by various factors such as work deadlines, relationship issues, or financial problems.

• Pressure can come from external sources like work responsibilities, academic expectations, or societal norms.

• Stress can ...read more

Mechanical engineering is evolving with advancements in technology like automation, robotics, and additive manufacturing.

• Automation and robotics are transforming manufacturing processes and increasing efficiency.

• Additive manufacturing, such as 3D printing, is revolutionizing prototyping and production.

• Integration of IoT and AI is enabling predictive maintenance and optimization of mechanical systems.

• Green technologies are driving the development of sustainable and energy-effi...read more

Design patterns are reusable solutions to common software development problems.

• Design patterns provide a common language for developers to communicate about solutions to common problems.

• They can improve the quality, maintainability, and scalability of software.

• Examples include the Singleton pattern, Factory pattern, and Observer pattern.

• Design patterns can be categorized into three groups: creational, structural, and behavioral patterns.

JVM is an environment to run Java programs, JRE is a runtime environment, and JDK is a development kit.

• JVM stands for Java Virtual Machine and is responsible for executing Java bytecode.

• JRE stands for Java Runtime Environment and provides a runtime environment for Java programs.

• JDK stands for Java Development Kit and includes tools for developing Java applications.

• JDK includes JRE and additional development tools such as compilers and debuggers.

• JVM is platform-dependent, whil...read more

Threads in Java can be created by extending the Thread class or implementing the Runnable interface.

• Extend the Thread class and override the run() method

• Implement the Runnable interface and implement the run() method

• Use the Executor framework for managing threads

React is a JavaScript library for building user interfaces.

• React uses a virtual DOM for efficient rendering

• It allows for reusable components and easy state management

• React is declarative, making it easier to understand and debug code

• It has a large and active community with many resources available

• React Native allows for building mobile apps with the same codebase

Annotations are used in Spring Boot for various purposes such as mapping requests, defining beans, and handling exceptions.

• Annotations are used to provide metadata to the Spring framework.

• They are used to map requests to controller methods using @RequestMapping.

• Annotations like @Component, @Service, and @Repository are used to define beans.

• Annotations like @ExceptionHandler and @ControllerAdvice are used for handling exceptions.

• Annotations like @Autowired and @Value are used ...read more

Java code to check if two strings are anagrams

• Create a function that takes in two strings as parameters

• Convert both strings to char arrays and sort them

• Compare the sorted char arrays to check if they are equal

Functional interface is an interface with only one abstract method.

• Functional interface can have any number of default or static methods

• It is used for lambda expressions and method references

• Examples include Runnable, Comparator, and Function interfaces

Prototype chaining is the mechanism in JavaScript where an object inherits properties and methods from another object.

• In JavaScript, each object has a prototype property which points to another object. When a property is accessed on an object, if it doesn't exist on the object itself, JavaScript looks for it in the prototype chain.

• If the property is not found in the immediate prototype, JavaScript continues to look up the chain until it finds the property or reaches the end o...read more

Closure is a function that captures the environment in which it was created, allowing it to access variables from that scope even after the scope has closed.

• Closure allows a function to access variables from its parent function even after the parent function has finished executing.

• It is created when a function is defined within another function and the inner function references variables from the outer function.

• Example: function outerFunction() { let outerVar = 'I am outer'; ...read more

Memoization is a technique used in computer science to store the results of expensive function calls and reuse them when the same inputs occur again.

• Memoization helps improve the performance of algorithms by avoiding redundant calculations.

• It is commonly used in dynamic programming to optimize recursive algorithms.

• Example: Fibonacci sequence calculation using memoization to store previously calculated values.

Use ViewModel to share data between fragments in Android

• Create a ViewModel class to hold the data to be shared

• Observe the ViewModel in each fragment to receive updates

• Use LiveData to ensure data is updated in real-time

Yes, I always have a backup plan in case of unexpected issues during testing.

• Always have a backup plan in case of unexpected issues during testing

• Backup plan may include using different testing tools or approaches

• Having a backup plan ensures smooth testing process even in challenging situations

Promises in Node.js are objects representing the eventual completion or failure of an asynchronous operation.

• Promises are used to handle asynchronous operations in a more readable and manageable way.

• They can be in one of three states: pending, fulfilled, or rejected.

• Promises can be chained using .then() to handle success and .catch() to handle errors.

• Example: const myPromise = new Promise((resolve, reject) => { ... });

Temporal dead zone is the period between entering scope and being able to access a variable.

• Occurs when trying to access a variable before it has been declared

• Caused by hoisting in JavaScript

• Results in a ReferenceError

• Example: accessing a let or const variable before its declaration

configure method is used to set up an object while configure service method is used to set up a service.

• configure method is used to set up an object before it is used

• configure service method is used to set up a service before it is used

• configure method is used in objects like HTTP request pipeline, while configure service method is used in services like authentication

• configure method is called once during application startup, while configure service method can be called multi...read more

Stream API in Java provides a functional approach to processing collections of objects.

• Allows for concise and readable code by using functional programming concepts like map, filter, and reduce.

• Enables parallel processing of data, improving performance for large datasets.

• Supports lazy evaluation, allowing for efficient use of resources.

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

Functional interfaces in Java are needed to enable the use of lambda expressions, which provide a concise way to implement single abstract method interfaces.

• Functional interfaces have exactly one abstract method and can have multiple default or static methods.

• They are used to enable the use of lambda expressions, which provide a concise way to implement the single abstract method.

• Examples of functional interfaces in Java include Runnable, Callable, and ActionListener.

Mutex is a synchronization primitive

• Controls access to shared resources

• Prevents race conditions

• Ensures only one thread can access resource at a time

Diagonal elements of a 3*3 matrix

• A diagonal element is the element that lies on the diagonal of a square matrix

• In a 3*3 matrix, the diagonal elements are the elements at (1,1), (2,2), and (3,3)

• The diagonal elements can be found by indexing the matrix using the same row and column number

Hardware refers to physical components of a computer, while RAM is a type of hardware that stores data temporarily.

• Hardware includes components such as the CPU, motherboard, and hard drive.

• RAM stands for Random Access Memory and is used to temporarily store data that the computer is currently using.

• Hardware is permanent and cannot be changed without physically replacing the component, while RAM can be upgraded or added to.

• Examples of hardware include a keyboard, mouse, and mo...read more

Memory leak in Android refers to a situation where an application uses memory inefficiently, causing unused memory to accumulate and not be released.

• Memory leaks can occur when objects are not properly released after use, leading to a buildup of unused memory.

• Common causes of memory leaks in Android include holding onto references to objects that are no longer needed, using static variables in a way that prevents them from being garbage collected, and registering listeners or...read more

GO uses goroutines and channels to handle concurrency efficiently.

• GO uses goroutines to achieve concurrency. Goroutines are lightweight threads managed by the Go runtime.

• Channels are used to communicate between goroutines. They provide a safe way to pass data between concurrent processes.

• GO also has a built-in 'sync' package for synchronization primitives like mutexes and wait groups.

• GO's 'select' statement allows for non-blocking communication between goroutines.

• GO's 'defer'...read more

Mutex in DBMS stands for mutual exclusion and is used to control access to shared resources to prevent data inconsistency.

• Mutex ensures that only one process can access a shared resource at a time

• It helps prevent data corruption and maintain data integrity

• Mutex is commonly used in database management systems to control access to critical sections of code

• Example: In a multi-threaded database system, mutex can be used to lock a table while it is being updated to prevent concurr...read more

Activity lifecycle in Android refers to the different states an activity goes through during its lifetime.

• There are several states in the activity lifecycle, including onCreate, onStart, onResume, onPause, onStop, and onDestroy.

• Activities can transition between these states based on user interactions or system events.

• Understanding the activity lifecycle is crucial for managing resources and maintaining a smooth user experience.

• For example, onPause is called when an activity i...read more

Java OOPs concepts include inheritance, encapsulation, polymorphism, and abstraction.

• Inheritance allows a class to inherit properties and behavior from another class. Example: class Dog extends Animal.

• Encapsulation involves bundling data and methods that operate on the data into a single unit. Example: private variables with public getter and setter methods.

• Polymorphism allows objects to be treated as instances of their parent class. Example: Animal class with different subcl...read more

A Hash Map is a data structure that stores key-value pairs and allows for fast retrieval of values based on keys.

• Use an array to store the key-value pairs

• Implement a hash function to map keys to indices in the array

• Handle collisions by using techniques like chaining or open addressing

Software Testing Lifecycle is a process that includes planning, designing, executing, and evaluating tests to ensure quality software.

• 1. Planning phase involves defining test objectives, scope, and resources.

• 2. Design phase includes creating test cases, test data, and test environment setup.

• 3. Execution phase is where tests are run, defects are logged, and results are analyzed.

• 4. Evaluation phase involves reviewing test results, identifying areas for improvement, and closing ...read more

Beans in Spring Boot are Java objects that are managed by the Spring IoC container.

• Beans are defined in the Spring configuration file or using annotations like @Component, @Service, @Repository, etc.

• Beans are singleton by default, but can be configured as prototype scope.

• Beans are instantiated, assembled, and managed by the Spring IoC container.

• Beans can have dependencies injected using @Autowired annotation.

• Example: @Component class MyBean {}

I have used several design patterns in my previous projects.

• Singleton pattern for ensuring only one instance of a class

• Factory pattern for creating objects without exposing the instantiation logic

• Observer pattern for implementing event handling

• Decorator pattern for adding functionality to objects dynamically

• Strategy pattern for encapsulating algorithms and making them interchangeable

• Adapter pattern for converting the interface of a class into another interface

• Facade pattern f...read more

Scenario mitigation involves identifying potential risks and developing strategies to minimize their impact.

• Identify potential risks and their likelihood

• Develop strategies to minimize impact of risks

• Create contingency plans for worst-case scenarios

• Regularly review and update mitigation plans

• Communicate mitigation plans to stakeholders

Array methods in JavaScript are built-in functions that allow manipulation and traversal of arrays.

• Some common array methods include: map(), filter(), reduce(), forEach(), and find().

• map() - creates a new array by applying a function to each element in the original array.

• filter() - creates a new array with elements that pass a certain condition.

• reduce() - applies a function against an accumulator and each element in the array to reduce it to a single value.

• forEach() - execute...read more