10+ Interview Questions and Answers

To add dependency SDKs for a particular build flavor, modify the build.gradle file and specify the dependencies for that flavor.

• Open the build.gradle file for your project

• Locate the section for the desired build flavor

• Inside the dependencies block, add the necessary SDK dependencies

• Sync the project to apply the changes

Coroutines are lightweight threads in Kotlin that allow for asynchronous programming without the overhead of traditional multithreading.

• Coroutines are cooperative, meaning they can pause and resume execution at specific points in the code.

• They are more efficient than multithreading because they don't require creating new threads for each task.

• Coroutines can be used for both CPU-bound and IO-bound tasks.

• They simplify error handling and make code more readable.

• Example: Using co...read more

MVVM is a software architecture pattern that separates the user interface from the business logic.

• MVVM stands for Model-View-ViewModel.

• Model represents the data and business logic.

• View represents the user interface.

• ViewModel acts as a mediator between the View and Model.

• Advantages include easier testing, separation of concerns, and improved maintainability.

• Example: Xamarin.Forms uses MVVM architecture for cross-platform mobile app development.

RX Java and RXAndroid are reactive programming libraries for Java and Android respectively.

• RX Java and RXAndroid allow for asynchronous and event-based programming.

• They use Observables and Subscribers to handle data streams.

• They simplify complex code and make it easier to handle concurrency.

• Example use cases include network requests and UI updates.

• RXJava is used in popular Android libraries like Retrofit and Room.

Spark optimisation techniques

• Partitioning data to reduce shuffling

• Caching frequently used data

• Using broadcast variables for small data

• Avoiding unnecessary data shuffling

• Tuning memory allocation and garbage collection

• Using efficient data formats like Parquet

• Using appropriate hardware configurations

• Optimizing SQL queries using DataFrame and Dataset APIs

Spark architecture is a distributed computing system that provides high-level APIs for processing large datasets.

• Spark architecture consists of a cluster manager, a distributed storage system, and a set of worker nodes.

• The cluster manager, such as Apache Mesos or Hadoop YARN, allocates resources and schedules tasks.

• The distributed storage system, like Hadoop Distributed File System (HDFS), stores the data across the cluster.

• Worker nodes execute the tasks and store intermediat...read more

A program to generate Fibonacci series

• Declare two variables to store the first two numbers of the series

• Use a loop to generate the subsequent numbers by adding the previous two

• Print the numbers in the series

Aggregation & grouping in Spark

• Aggregation is the process of combining data from multiple sources into a single result

• Grouping is the process of dividing data into groups based on a specific criteria

• Spark provides various functions for aggregation and grouping such as groupBy, reduceByKey, aggregateByKey, etc.

• These functions can be used to perform operations like sum, count, average, etc. on grouped data

A fact is a measurable piece of data that represents a specific business aspect. Types include additive, semi-additive, and non-additive facts.

• A fact is a piece of data that can be measured and analyzed in a data warehouse

• Additive facts can be aggregated across all dimensions, such as sales amount

• Semi-additive facts can be aggregated across some dimensions, such as inventory levels

• Non-additive facts cannot be aggregated, such as average temperature

To extend Thread class in Java, we need to create a new class and inherit it from the Thread class.

• Create a new class and inherit it from the Thread class

• Override the run() method to define the task that the thread will perform

• Instantiate the new class and call the start() method to start the thread

The expected output is to capitalize the first letter of each word in the input string.

• Split the input string by space to get individual words

• Capitalize the first letter of each word

• Join the words back together with a space in between

Reverse the order of words in a given string.

• Split the input string by space to get individual words

• Reverse the array of words

• Join the words back together with a space in between

Custom pipes and directives are used in Angular to transform data and manipulate the DOM.

• Custom pipes can be created by implementing the PipeTransform interface and defining a transform method.

• Custom directives can be created by using the @Directive decorator and defining the desired behavior.

• Example of custom pipe: transforming a string to uppercase.

• Example of custom directive: highlighting an element on hover.

Garbage collection in Java is an automatic process of freeing up memory occupied by objects that are no longer in use.

• Garbage collection is performed by JVM

• It frees up memory by removing objects that are no longer in use

• It helps prevent memory leaks and improves performance

• Java provides different types of garbage collectors such as Serial, Parallel, CMS, and G1

• Developers can also manually request garbage collection using System.gc() method

Group array of objects by key

• Use Array.reduce() method to group objects by key

• Create an empty object to store the grouped objects

• Iterate over the array and check if the key already exists in the grouped object, if not create a new key and add the object to it