Capgemini Java Developer 4 yrs interview Questions and Answers L2 round #capgemini

Summary

The conversation revolves around a job interview for a Java developer role. The interviewer asks technical questions regarding Java, Spring Boot, microservices, and related technologies. The candidate discusses their experience with Java 8, Lambda functions, stream APIs, and their involvement in API development using Spring Boot. They also address scenarios on sorting employee data, writing custom queries, and handling API requests. The discussion extends to testing methods, such as JUnit, and the candidate expresses interest in learning more about microservices architecture.

Takeaways

• 😀 The candidate is a Java developer with 4.1 years of experience.
• 📍 The candidate is currently based in Gorakpur, UP, and willing to relocate to Bangalore or Chennai for work.
• 💻 The candidate has experience in banking and healthcare domains, working with Java, Spring Boot, and MySQL.
• 🔧 The candidate is proficient in using Java 8 features such as Lambda expressions, Stream API, and Optional class.
• 📝 The candidate is asked to write Java code to filter employees based on location and sort a list of employees by name and age.
• 🛠 The candidate discusses the use of functional interfaces like Predicate, Consumer, and Supplier in Java.
• 📈 The candidate is familiar with Spring Data JPA and its advantages over traditional Repositories.
• 🔄 The candidate explains how to design an API to fetch the first five records from an employee table using Spring Boot.
• 🌐 The candidate is aware of the concepts of microservices and the shift from monolithic architectures.
• 📊 The candidate uses Actuator for monitoring and managing applications.
• 📝 The candidate tests applications using JUnit 5.

Q & A

What is the job requirement mentioned in the transcript?

The job requires a Java developer with a good understanding of Java, Spring Boot, and microservices. Hands-on experience with CI/CD is an added advantage. The candidate should be willing to work in a hybrid model from Bangalore or Chennai.

What is the candidate's current location and are they willing to relocate?

The candidate is currently in Gorakpur, UP, but is willing to relocate. They have previously lived in Bangalore and will manage the relocation.

What technologies has the candidate worked with in their past projects?

The candidate has worked with Java, Spring Boot, Hubs framework for the front end, MySQL for the database, and has experience with APIs. They have also used Java 8 features such as Lambda expressions and Stream API.

What is the project methodology used by the candidate's current project?

The candidate's current project uses the Agile methodology with Sprints lasting 15 days.

What Java version has the candidate used and what features are they familiar with?

The candidate has used Java 8 and is familiar with Lambda functions, Function Interface, Stream API, and the Optional class.

How does the candidate approach writing code for filtering employees based on location?

The candidate would use Java to filter the employee list based on the location, specifically filtering for employees from Chennai.

What is the scenario given to the candidate for sorting a list of employees?

The candidate is asked to sort a list of employees by their names, and if names match, then sort by their age.

Can one functional interface inherit another, according to the candidate?

Yes, one functional interface can inherit another, but it will have more than one abstract method if it does so.

How does the candidate plan to design an API to get the first five records from an employee table?

The candidate would create a Spring Boot project, add MySQL driver and Spring Data JPA dependencies, configure the property file for database connection, define the entity class, create a service layer, and use a custom finder method in the repository to fetch the first five records.

What is the difference between a JPA repository and a traditional repository according to the candidate?

The candidate mentions that JPA repositories provide additional functionality like paging and sorting, which are not available in traditional repositories.

How does the candidate handle different output formats (JSON and XML) for an API?

The candidate suggests using the @ResponseBody annotation to return the appropriate format, with JSON being the default and XML handled by using a different response body configuration.

How has the candidate used Spring Boot Actuator in their projects?

The candidate has used Spring Boot Actuator for monitoring and managing the health of their deployed applications, checking for created beans, loggers, and heap usage.

Outlines

00:00

👨‍💻 Java Developer Role Overview and Introduction

In this paragraph, the speaker outlines the job requirement for a Java Developer role. Key skills required include Java, Spring Boot, Microservices, and hands-on experience with CI/CD. The role is hybrid, based in Bangalore or Chennai. The speaker briefly checks the candidate's willingness to relocate, and the candidate confirms their readiness to move from Gorakhpur, Uttar Pradesh.

05:01

👨‍💼 Candidate's Technical Background and Project Experience

The candidate introduces themselves as B. Singh with 4.1 years of experience in IT. They describe working in the banking and healthcare domains with Java, Spring Boot, and MySQL. The candidate details their experience with API support, service logic manipulation, and involvement in development tasks using Java's latest features such as Lambda expressions, Stream API, and Optional classes. They also touch on their involvement in agile methodology, working in 15-day sprints, and using Java 8.

10:04

🧑‍💻 Coding Challenge: Filter and Sort Operations

The interviewer gives the candidate a coding scenario to filter employee ages based on location (Chennai) using Java 8 features. The candidate explains how they would filter the list and extract the relevant ages. They are then asked to sort employees by name, with a secondary sort by age if the names match. The candidate suggests using Comparator, explaining its functionality compared to Comparable, and shares their understanding of functional interfaces such as Predicate, Supplier, and Consumer.

15:07

📊 API Design: Fetching Data from Database

The candidate is asked to explain how they would design an API to retrieve the first five records from an employee database. They explain how they would configure the project with necessary dependencies, use JPA Repository, and customize queries if needed. The candidate discusses the use of custom queries and native SQL to retrieve records, with additional discussion on the difference between JPA Repository and CrudRepository. They also briefly touch upon returning data in different formats like JSON and XML.

20:09

🛠 Microservices, Monolithic Architecture, and Testing

The candidate discusses microservices, including its advantages over monolithic architecture, such as easier scalability, manageability, and deployment. They explain how services in microservices architecture can be deployed separately, reducing downtime. The candidate also mentions their experience with JUnit 5 for testing service layers and repository methods. Finally, they express their willingness to learn more about microservices despite limited hands-on experience.

Keywords

💡Java

Java is a high-level, class-based, object-oriented programming language that is designed to have as few implementation dependencies as possible. It is a general-purpose programming language used for building various types of applications. In the video, the candidate discusses their experience with Java, particularly in the context of backend development using frameworks like Spring Boot.

💡Spring Boot

Spring Boot is an open-source Java-based framework used to create stand-alone, production-grade Spring applications. It simplifies the configuration of Spring applications and reduces the complexity of enterprise applications. The candidate mentions using Spring Boot extensively in their work, indicating its importance in modern Java development.

💡Microservices

Microservices is an architectural style that structures an application as a collection of loosely coupled services. It allows the services to be developed, deployed, and scaled independently. The candidate briefly discusses microservices, showing an understanding of the shift from monolithic architectures and the benefits of scalability and flexibility it offers.

💡CI/CD

CI/CD stands for Continuous Integration and Continuous Delivery/Deployment. It is a practice where code changes are automatically built, tested, and prepared for release. The candidate mentions having hands-on experience with CI/CD, which is a valuable skill in modern software development for ensuring code quality and efficient deployment processes.

💡Hybrid Model

A hybrid model refers to a combination of different methodologies or technologies. In the context of the video, it likely refers to a mix of remote work and in-office work. The candidate confirms their willingness to relocate for work, indicating flexibility in adapting to different work environments.

💡Lambda Functions

Lambda functions are a feature in Java 8 that allows for the creation of anonymous functions that can be passed as arguments or executed in a different thread. The candidate discusses using Lambda functions for data manipulation and collection operations, demonstrating their practical application in streamlining code.

💡Stream API

The Stream API is a part of Java 8 that allows for a high-level, functional-style operations on streams of elements, which can be used to express computations on collections in a declarative way. The candidate mentions using the Stream API for data manipulation, highlighting its role in handling collections efficiently.

💡Optional Class

The Optional class in Java is used to avoid null checks and make the code cleaner and less error-prone. It is used to represent a value that may or may not be present. The candidate discusses using the Optional class, indicating an understanding of how to handle nullable values in Java.

💡API Development

API stands for Application Programming Interface and is a set of routines, protocols, and tools for building software applications. The candidate talks about their experience in developing APIs using RESTful services, which are a cornerstone of modern web services architecture.

💡JUnit

JUnit is a unit testing framework for the Java programming language. It is used to write repeatable tests for Java code. The candidate mentions using JUnit 5 for testing service layers and repository layers, emphasizing the importance of testing in the software development lifecycle.

💡Actuator

Spring Boot Actuator is a powerful tool for monitoring and managing your application. It provides insights into what's happening in the running application. The candidate discusses using Actuator for application monitoring, showing an understanding of the importance of application health and performance monitoring.

Highlights

Requirement for a Java developer with expertise in Java Spring and microservices.

Experience with CI/CD is considered an advantage.

The candidate must be willing to work in a hybrid model from Bangalore or Chennai.

Candidate introduces himself as B. Singh with 4.1 years of IT experience.

Worked on banking and healthcare domains, primarily with Java and Spring Boot.

Experience with databases such as MySQL.

Involved in API development and service layer manipulation.

Uses Agile methodology with Sprints typically lasting 15 days.

Java 8 is the primary version used, with features like Lambda functions and Stream API.

Scenario given to write code to filter employees by location and print their ages.

Second scenario involves sorting a list of employees by name and age.

Discussion on functional interfaces like Predicate, Supplier, and Consumer.

Explanation of intermediate and terminal operations in Java Streams.

Project involves writing REST APIs for database communication.

Design approach for an API to get the first five records from an employee table.

Difference between JPA Repository and a traditional Repository.

Handling different output formats (JSON and XML) for API responses.

Use of Actuator for application monitoring and management.

Awareness of microservices architecture and its advantages over monolithic applications.

Testing applications using JUnit 5.

Transcripts

thank you uh could you identify with the

government em yes uh this

one till back it's uh going beyond the

screen till in front of the

camera it should not cover your face it

is covering your face

okay thank you thanks

for identification uh so because uh just

a brief you on the requirement okay it's

again a Java developer Ro uh having a

good understanding on Java springboard

microservices some handson on J cicd

would be an added Advantage okay so this

is a type of uh skill set requir and

person has to be working from Bangalore

or Chennai in an hybrid mod okay okay

okay so I hope you clear with the

requirement uh yes sir so where where

are you based currently uh currently I'm

in my hometown my hometown is gorakpur

up okay so you are working I mean you

are okay to relocate yes yes I will

relocate no problem G uh the at the time

of CC I live in Bangalore so

no I will relocate I will

manage okay so uh can you just brief

about yourself let me know about the

project the technology stack you have

been working on so okay so my name is B

Singh and I have total 4.1 year of

experience in IT background in my first

company intellect design Arena I work

for a banking domain so we have a

product like import LC export LC backto

back LC uh this uh product based on for

the front end we are using hubs

framework internal framework and for the

back end we are using mostly Java and

spring Embassy spring boot mostly I'm

using and for the database we are using

MySQL and my uh recent company I working

for healthcare domain so here also same

we are using spring boot mostly we are

using and some Java code Java we are

using Java new features also we are

using and mostly I involve in the like

API support so whatever the requirement

endm is coming so based on that we are

going to manipulate that service logic

and service layer and give the API

support for that for the marting so

mostly I involve in

like take Development Area so mostly I

work in this framework and that's it

from my

set sorry so in the current project what

is the uh project methodology like are

you using a currently yes we are using

that aile

methodology okay so what are what are

the meetings or how how how what what

duration is your

Sprint so mostly uh in the development

phase or Sprint is 15 days or mix to

nextx 13 days some cases is uh mostly is

a 15 days that is print so whatever we

have so in within the time we are going

to deploy all those code and in the

Sprint

so 15 days is

maximum okay so what is the Java version

you have been using so mostly we are

using uh java8 we are using in my

project so what are the features of

java8 that you worked

on so like if I'm talking about what I'm

using like mostly we are using Lambda

function we are using and function

interface the function manner we are

using and mostly for the data

manipulation or collection object for

the we are using a stream API and so

there are many new features we have

already like optional class mostly we

are using so option class we are using

and Lambda expression we are using

Lambda function also we are using stream

May mostly are

used okay I'll give you a scenario if

you can write a code okay if you if you

can open notepad ID whatever I don't

want you to run it just the logic I want

you to write consider you have an

employee list okay consisting of

employee objects okay uh so employe is

an entity consisting of ID name age

location of the employee okay so you

have to use Java it basically and uh

just

uh print the age of the employees who

are from uh you know Chennai location

maybe okay so we are going to print is

uh based

[Music]

on location based on location like based

on

loc so suppose that we

have so suppose that we have a list of

this

emplo EMP this is a we have a list I

think

so print the Age based on the location

so we need to print the Age based on the

location in the scenario or you can make

it simpler we have to print the ages of

all the employees who are from chenai

location okay

so gu

filter first we need to filter that

location locational

based on that location we need to

[Music]

filter we can pass that one

hello yeah yeah tell

me okay so first we need to filter out

the

object mistake here we need to filter

out and

do location I think good location

[Music]

[Music]

first

this

uh so this way we are going to print

this

one okay the location is CH then you're

collecting the

age okay so this is you get the age okay

now I'll give you one more scenario okay

uh first sort this same list sort this

list by the names of the employees okay

uh for example employee one is vikas uh

staying in Bangalore employee 2 is sha

staying in Mumbai employee ID 3 is

another vas staying in Chennai okay so

the employ ID are different but the

names are same right so sort the

employee list based on the names of the

employees and if names match like one

and three have same names then s by h of

the

employe so first we need to sort based

on the name and then we having the

duplicate

so need to sort by the

age

M so first we need to sorting

so I'm

comparing shorted computer comparing

not

comping can you repeat that scenario

once yeah yeah

yeah the names match s by the

h no first if the first we need to sort

based on that

name and then we need to name match then

only sort

by okay so we are going to

short compor comparing

so name need to start in or ascending or

any reverse

order yeah uh any any ORD fine that you

want to

[Music]

have have

and this one so so just

Computing so just filter this sorting

this I'm not sure we can use equals to

equals to here or not

but so so why are you using a comparator

here and why not a comparable

so if I'm using that so I need to pass

that like object we need to pass o1

comma O2 and then o1 dog name we need to

compare compare two method we can use so

here I'm just passing this compor do

this function I'm directly use by

natural order

or

this this way also we can use compar to

Method we can use like I'm using that

one also

okay so what are some of the other

functional interfaces that you have

used the function interfaces like

predicates we are using predicate

supplier

consumer all this predicate function

interface we are using so only one

abstract method is there and there is no

restriction of static method and default

method so like in predicate we have a

text method and consumer we have a

accept method this U

abstract method we

have okay okay uh moving ahead in this

statement okay for example you consider

this line number five what are the

intermediate and terminal operations

that you

using okay so we have this

filter so filter is the part of

intermediate operation and this collect

also the collect is a part of like

terminal and for each also part of

terminal and the mean Max and so in that

intermediate operation we have reduced

filter flat map map this part of

intermediate this we this

filter in

jaace ined in

jav yes I heard about that M some like

previously we have some enhan in memory

based on that like Palm engine is this

concept is there

permanent so it's introduced like

enhancement is coming so m space

introduced previously a per engine

permanent memory space is there so some

due to the lack of memory issue they are

going to introduce in the metal space

I'm not much more

about more about but I heard about that

space so regarding functional interfaces

that you're mentioning can one

functional interface inherit another

function

interface no see if one functional

interface uh if yeah it can be inherit

but uh that is not part of that function

interface because that uh if other

interface going to extend so so one

abstract met is going to be the coming

from the parent and it we defining so we

have like a normal interface so we can

uh yes we can extend

that okay okay oving to uh

your writing apis and all in your

project currently uh yes for the like

resource uh resource update or delete or

fast like database communication we are

writing Rest API so controller we are

written for rest controller and inside

that we are defining all those method

which are which is going to handle that

a protocol protocol going to

handle can okay

uh okay so I'll give you one scenario I

want you to tell me how will you design

this okay uh consider uh you have a same

employee table if you want to write an

API to get the first five records from

this employee

table okay how how will you go about

implementing this what are the classes

involved how will you connect to the

database I want you to explain me on

that okay so uh firstly whenever uh

suppose mostly I'm using like STS I'm

using so from the spring iner I'm going

to create one project and if I want to

communicate with the database so I need

to add some for starters like for the

database we have MyQ driver and this

dependency we are required MyQ driver

and data GPA this need once the project

is going to create it so first we are

going to configure our property file so

inside that we are configure all the

database related stuff like

spring spring. data source username

password driver name and class name all

those things and once database is

connected then we are going to create

like one structure we are going to

create for the database so for that we

are going to create one uh like classes

inside that we are creating a separate

class and Mark as that class at theate

entity class so we are going to uh

Define classes and whatever the

attribute I'm defining so through that

we are going going to create the

structure of that database so once the

database going to be created So based on

that we are going to write one uh

service layer I'm going to write so in

that service layer we are going to

Define that method that method going to

execute based on the requirement and

fetching the data so for the DB like

fetching the data so we are not directly

we are going to fet the data from the DB

so we are just using the like we are

using data jpa Repository so okay GP

repository I'm using so for that I'm

going to create one repository CL

repository interface extend by the data

data GP repository and then inside if I

extending so we just passing that ID

comma serializable also we can pass that

the name we can pass and then we can use

the Inu method like find by ID find by

name so if you want to like if you uh

what you want to stct the

data no I want I want you to write the

API to get the first P records from

employee

table

okay so then we are writing so we are

writing the service class so find by

find the data like find the users I'm

going to create one uh service layer

creating the one method and then

creating the implementation I give the

implementation for that and what about

the repository of defining so by using

inside that we have custom finder method

also we can Define find my suppose that

if I'm separate if I want to create

separate method and execute some custom

query so I'm just creating like find by

name so sorted name we can that that

type

of no no but in this scenario when I

need the first F

records do you have any custom method

which can be used or any method which

can be used or you need to write a

custom query yeah because like we have

find by ID this type of method we have

sa find by ID so I don't know it's going

to f the

record but we need to write I think

custom query or native query we need to

write in this case so that's why I

thought we need to a custom finder

method we can write and based on that we

query we through that we are going to

fire one query and then we are going to

create the one the rest controller class

and write one method so that method

going to handle the HTTP request from

the front

end so I think this is the so what sort

of query suppose if you want to write

this query in a normal SQL to get the

first how how will you write the query

so select like select employee like

select start from employee and ordered

by descending and then I'm using the

limit 1 to five then it's printing only

the 5 code

M so uh you said you're raising a jpa

repository right so what's the

difference between a jpa and a credit

Repository

yes so this two extra facility we are

getting in GP repository like paging and

shorting so that purpose we are mostly

using I'm not using that shorting and P

and this extra functionality we have in

GP repository rather than

repository okay so now consider you have

written this AP okay and there are

customers are going to call this

APM some of them want an output in Json

format and some of them need an output

in XML format how do we handle

this so I think some in that method

level mostly response body we are using

so procedure equals to some tag we are

using so rather than Json we are stml

object we are going to

WR so

some procedure equals to something that

I'm missing that

name okay okay uh how actuators have you

used actuators anytime in the

project actuator yes once we like

develop our application so once we

deploy that server so we are going to

manage monitoring that application so

that purpose we are going to use the

acuator so yes again we are going to add

one dependency like acuator dependenc

and then based on that we are going to

monitor and check the health of our

application how many the beans is

created that loggers and that Heap and

something so by the actuators we can

manage and monitoring that

application okay so uh so the concern

I'll talk about it are working on

Microsoft I'm not getting

much micros Services I'm not involved in

that so but yes I'm aware of that and

I'm try willing to learn more about the

microservices recently I'm trying to

work on that so I'm aware of that like

what why we are switching monolithic to

micro Services what is the advantage

disadvantage what is the API Gateway

Services what is the advantage or what

is the disadvantage you have in this

monolithic application that's so the

everybody is trying to move to

microservice based market so the the

most disadvantage of Monolithic we are

going to all the services we are binding

at a single places so all the large

application we are not going to break

down that so in the main disadvantage

whenever we are going to do the sort of

short like we are going to do Implement

any particular Services then it's a

minor change then still we are going to

the time of deployment we are going to

deploy all the project so it's time

going to consuming so that that is one

reason and so that's why suppose that we

have a microservice architecture so all

the services work as a different

different microservices so if any

requirement changes or anything happen

in the particular services so we are

just going to uh minor change in that

particular service and deploy separately

them and manage that micros service

separate team or written by the

different different language so

internally we are going to communicate

with different different uh

microservices so it's easy to manage it

easy to deployment in easy to scalable

our project if we follow the

microservices rather

than so um moving to testing part how

how are you testing your

application junit I

use J unit five I use for the whatever

the service layer and we have a

repository like Dow layer we have if I'm

writing one method so that time we need

to write U test cases for that

particular method yeah g 5 I'm used

mostly at the test