Techno Interview

SpringBoot

COURSES

02 Month
DURATION

01 Hours

Difference between Spring vs SpringBoot

Spring	SpringBoot
Spring is good for j2ee/JDBC application.	SpringBoot is good for restful web services.
Dependency injection is an important part	Springboot Autoconfiguration is important aspect
Spring is structure based framework	Springboot is annotation based framework
Spring is loosely coupled application	SpringBoot is stand alone application
Spring use boilerplate code to make application loosely coupled	SpringBoot does not use boilerplate code
Spring boot is xml based application where property must be defined under pom.xml	SpringBoot is starter based application where starter itself take care for configuration
Embadded server such as tomcat ,jetty must be defined explicitly	SpringBoot already included with tomcat embedded server no need to define explicitly

Difference btw @RestController and @Controller

@RestController	@Controller
It is combination of controller and response body do not need to define explicitly	Controller convert data to human readable format, Response body need to defined explicitly
Convert data to json and xml both	Convert data to xml format only

Define @RequestMapping in springboot application

It is a generic annotation using with class and method in order to map the data to the controller
When used with class it must include URL of API ,but when used with method of rest API
it must include Request method along with it.

Difference between @RequestMapping vs @GetMapping

@RequestMapping	@GetMapping
RequestMapping is generic annotation, which is used map the web request.	@Getmapping is class level annotation with specific to get call.
Along with RequestMapping we need to define request method	@GetMapping do not need request method separately.

what are different interface of SpringBoot?

Four interface of Springboot are:

Springboot starter
Springboot CLI
Springboot Actuator
Springboot Autoconfiguration

Define @SpringbootApplication annotation

This annotation is combination of three annotation @EnableAutoConfiguration, @componentScan and @configuration ,it is used by spring boot in main class of application.

✓ @EnableAutoConfiguration: – it auto configures the class according to starter, create the bean and register it to the jar

✓ @componentScan: - Scan the package for us configure component, service and repository

✓ @configuration: – Handel basic configuration to maintain the code flow

Define @Require annotation

This annotation is used to detect property which must be checked by JVM at the time of compilation.

How to change the port no from 8080 to 8032 in SpringBoot?

For changing the port no in Springboot we can change it application.
properties file present in resources folder by server. port = 8032

How to change default embedded server to other server?

Springboot support three embedded servers i.e.

Apache Tomcat
Jetty
Underflow

Apache Tomcat is default server that comes along with Springboot. For changing it to tomcat to jetty

Exclude the property of starter-tomcat.
Include the property of starter-jetty.

How to connect SQL in Springboot?

Create database in MySQL.
Open the SpringBoot project.
Add SpringBoot Web, JDBC, MySQL connector dependencies under pom.xml.
Configure db properties under application.Properties.
Run application as java application/springboot application

spring.datasource.url= jdbc:mysql://localhost:3306/medicomart
        spring.datasource.username=root
        spring.datasource.password=admin
        spring.jpa.generate-ddl=true

What are different Stereotype annotation?

@Entity: Used to define basic entity, also entity class.
@Component: Generic annotation type which used for define common class level
@Service: Service class is defined where all service method is called
@Repository: define repository which implements JPA repository.

Difference between Intermediate and Terminal

Intermediate	Terminal
Intermediate operations return a stream	Terminal operations return non-stream values like primitive or object or collection
Chained together to form a pipeline of operations	Terminal operations can not be chained together
Lezy by nature	Execute as soon as created
They don’t produce end result.	They produce end result.
map() filter() distinct() sorted() limit() skip()	forEach() toArray() reduce() collect() min() max() count() anyMatch() allMatch() noneMatch() findFirst() findAny()

Difference between map vs Flatmap

Map	Flatmap
processes stream of values.	processes stream of stream of values.
It does only mapping.	It performs mapping as well as flattening.
It’s mapper function produces single value for each input value.	It’s mapper function produces multiple values for each input value.
It is a One-To-One mapping.	It is a One-To-Many mapping
Data Transformation : From Stream to Stream	Data Transformation : From Stream of Stream to Stream

List<String> namesOfInstitutes
            = instituteList.stream().map(Institute::
            getName).collect(Collectors.toList());

Set<String> locationsOfInstitutes
                = instituteList.stream()
                .flatMap(institute -> institute.getLocations().stream()).
                collect(Collectors.toSet());

Difference between Collection and Steam

Collection	Stream
Part of JDK 1.2	Part of JDK 1.8
Used to store different type of object in a single entity.	Streams are mainly used to perform operations on data.
used for finite value of data.	used for infinite value of data.
add or remove elements from collections	can’t add or remove elements from streams
Collections can be traversed multiple times	Streams are traversable only once.
Collections are eagerly constructed.	Streams are lazily constructed.
Example :-List, Set, Map	Example : –filtering, mapping

Difference between Iterator vs Splitor

Iterator	Splitor
iterator is part of JDK 1.2	splitor is part of JDK1.8
iterator part of collection Api	Splitor is part of steam Api
Only Sequential order	Both Parallel and Sequential order
it is pure Iterator	it is unpure Iterator

StringJoiner in Java8

Joining the strings or concatenating the strings is the frequent
operation while programming any kind of applications.

java.util.StringJoiner class
String.join() method
Collectors.joining() method

StringJoiner Example : Joining the strings with delimiter

import java.util.StringJoiner;
 
            public class Java8StringJoiner 
            {
                public static void main(String[] args) 
                {
                    StringJoiner stringJoiner = new StringJoiner(" | ");
                     
                    stringJoiner.add("Facebook");
                     
                    stringJoiner.add("Twitter");
                     
                    stringJoiner.add("YouTube");
                     
                    stringJoiner.add("WhatsApp");
                     
                    stringJoiner.add("LinkedIn");
                     
                    System.out.println(stringJoiner);
                }
            }
            Output :
            
            Facebook | Twitter | YouTube | WhatsApp | LinkedIn

StringJoiner Example : Joining the strings with delimiter, prefix and suffix

import java.util.StringJoiner;
 
                public class Java8StringJoiner 
                {
                    public static void main(String[] args) 
                    {
                        StringJoiner stringJoiner = new StringJoiner(", ", "[", "]");
                         
                        stringJoiner.add("Facebook");
                         
                        stringJoiner.add("Twitter");
                         
                        stringJoiner.add("YouTube");
                         
                        stringJoiner.add("WhatsApp");
                         
                        stringJoiner.add("LinkedIn");
                         
                        System.out.println(stringJoiner);
                    }
                }
                
                Output :
                
                [Facebook, Twitter, YouTube, WhatsApp, LinkedIn]

String.join() Method Example : Joining the strings

public class Java8StringJoinMethod 
                    {
                        public static void main(String[] args) 
                        {
                            String joinedString = String.join(" | ", "Facebook", "Twitter", "YouTube", "WhatsApp", "LinkedIn");
                             
                            System.out.println(joinedString);
                        }
                    }
                    
                    Output :
                    
                    Facebook | Twitter | YouTube | WhatsApp | LinkedIn

String.join() Method Example : Joining an array of strings

public class Java8StringJoinMethod 
                        {
                            public static void main(String[] args) 
                            {
                                String[] strArray = new String[] {"Facebook", "Twitter", "YouTube", "WhatsApp", "LinkedIn"};
                                 
                                String joinedString = String.join(" | ", strArray);
                                 
                                System.out.println(joinedString);
                            }
                        }
                        
                        Output :
                        
                        Facebook | Twitter | YouTube | WhatsApp | LinkedIn

String.join() Method Example : Joining list of strings

import java.util.Arrays;
                            import java.util.List;
                             
                            public class Java8StringJoinMethod 
                            {
                                public static void main(String[] args) 
                                {
                                    List<String> listOfStrings = Arrays.asList("Facebook", "Twitter", "YouTube", "WhatsApp", "LinkedIn");
                                     
                                    String joinedString = String.join(" | ", listOfStrings);
                                     
                                    System.out.println(joinedString);
                                }
                            }
                            
                            output:
                            Facebook | Twitter | YouTube | WhatsApp | LinkedIn

What is Method Reference

Method reference used to refer to the method of functional interface.
It can be used to replace Lambda Expression while referring to a method.

Lembda Expression	Equivalent Method Reference
(String s)->integer.parseInt	integer::parseInt
(String s)->s.toLowerCase	String::toLowerCase
(int i)->System.out.println(i)	System.out::println
(Student s)->s.getName();	Student::getName
()->s.getName()	s::getName
()->new Student()	Student::name

import java.util.function.Function;

                public class Java8MethodReferences {
                    public static void main(String[] args) {
                        //Calling parseInt() method using lambda
                
                        Function < String, Integer > lambdaFunction = (String s) - > Integer.parseInt(s);
                        System.out.println(lambdaFunction.apply("12"));
                
                        //Calling parseInt() method using method reference
                
                        Function < String, Integer > referenceFunction = Integer::parseInt;
                        System.out.println(referenceFunction.apply("12"));
                    }
                }