Top Twenty Boundary Balance Interview Questions Answers For Java/Jee Programmers
Hello guys, I receive got been sharing roughly REST amongst Spring tutorials from concluding a twain of weeks together with today, I am going to part roughly of the often asked Spring together with REST interview questions to Java developers applying for Web developer roles. Since Spring Framework is the most pop together with the measure framework for developing Java spider web application together with RESTful Web Services, a proficient noesis of Spring inwardness together with Spring MVC is expected from whatever senior Java developer, but if the undertaking description call close REST together with Web Services, y'all likewise demand to endure aware of how to develop RESTful Web Services using Spring Framework. From Spring 3.1, the framework has been enhanced a lot to back upwards many features needed for RESTFul API out-of-the-box e..g HTTPMessageConverter tin convert your HTTP response to JSON or XML yesteryear but detecting relevant library inwards classpath e.g. Jackson together with JAXB.
Spring likewise provides customized annotations for RESTful Web Services e.g. @RestController which tin brand your Controller REST aware, so that y'all don't demand to do mutual materials required yesteryear every unmarried REST API e.g. converting the response to JSON.
Influenza A virus subtype H5N1 proficient noesis of Spring Security is likewise mandatory for developing together with safety RESTful Web Services inwards the existent world. Since y'all cannot brand life a non-trivial REST API without security, a proficient noesis of safety basics e.g. HTTP basic authentication, digest authentication, OAuth, together with JWT is real important.
Btw, If y'all are non familiar amongst that concept, I advise y'all acquire through REST amongst Spring together with Learn Spring Security Course to gain roughly sense before your Interview. These ii courses are specially designed to render y'all roughly real-world sense to boost both your noesis together with sense amongst Spring MVC, REST, together with Spring Security.
What does REST stand upwards for? (answer)
REST stands for REpresentational State Transfer, which uses HTTP protocol to shipping information from customer to server e.g. a mass inwards the server tin endure delivered to the customer using JSON or XML.
What is a resource? (answer)
Influenza A virus subtype H5N1 resources is how information is represented inwards REST architecture. By exposing entities every bit the resources it allows a customer to read, write, modify, together with create resources using HTTP methods e.g. GET, POST, PUT, DELETE etc.
What are rubber REST operations? (answer)
REST API uses HTTP methods to perform operations. Some of the HTTP operations which doesn't alteration the resources at the server is known every bit rubber operations e.g. GET together with HEAD. On the other hand, PUT, POST, together with DELETE are dangerous because they alteration the resources on the server.
What are idempotent operations? Why is idempotency important? (answer)
There are roughly HTTP methods e.g. GET which arrive at same response no affair how many times y'all exercise them e.g. sending multiple GET asking to the same URI volition resultant inwards same response without whatever side-effect thence it is known every bit idempotent.
On the other hand, the POST is non idempotent because if y'all shipping multiple POST request, it volition resultant inwards multiple resources creation on the server, but again, PUT is idempotent if y'all are using it to update the resource.
Even, multiple PUT asking to update a resources on a server volition give same terminate result. You tin farther accept RESTful Web Services to acquire to a greater extent than close REST.
What are the advantages of the RestTemplate? (answer)
The RestTemplate course of report is an implementation of Template method pattern inwards Spring framework. Similar to other pop template classes e.g. JdbcTemplate or JmsTempalte, it likewise simplifies the interaction amongst RESTful Web Services on the customer side. You tin exercise it to swallow a RESTful Web Servicer real easily every bit shown inwards this example.
Which HTTP methods does REST use? (answer)
REST tin exercise whatever HTTP methods but the most pop ones are GET for retrieving a resource, POST for creating a resource, PUt for updating resources together with DELETE for removing a resources from the server.
What is an HttpMessageConverter inwards Spring REST? (answer)
An HttpMessageConverter is a Strategy interface that specifies a converter that tin convert from together with to HTTP requests together with responses. Spring REST uses this interface to convert HTTP response to diverse formats e.g. JSON or XML.
Each HttpMessageConverter implementation has i or several MIME Types associated amongst it. Spring uses the "Accept" header to create upwards one's heed the content type customer is expecting.
It volition so elbow grease to divulge a registered HTTPMessageConverter that is capable of treatment that specific content-type together with exercise it to convert the response into that format before sending to the client.
How to create a custom implementation of HttpMessageConverter to back upwards a novel type of request/responses? (answer)
You but demand to create an implementation of AbstractHttpMessageConverter together with register it using the WebMvcConfigurerAdapter#extendMessageConverters() method amongst the classes which generate a novel type of request/response.
Is REST commonly stateless? (answer)
Yes, REST API should endure stateless because it is based on HTTP which is likewise stateless. Influenza A virus subtype H5N1 Request inwards REST API should incorporate all the details required it to procedure i.e. it should non rely on previous or adjacent asking or roughly information maintained at the server terminate e.g. Sessions. REST specification set a constraint to acquire far stateless together with y'all should drib dead on that inwards heed spell designing your REST API.
What does @RequestMapping notation do? (answer)
The @RequestMapping notation is used to map spider web requests to Spring Controller methods. You tin map asking based upon HTTP methods e.g. GET together with POST together with diverse other parameters. For examples, if y'all are developing RESTful Web Service using Spring so y'all tin exercise produces together with consumes belongings along amongst media type notation to betoken that this method is solely used to arrive at or consumers JSON every bit shown below:
Is @Controller a stereotype? Is @RestController a stereotype? (answer)
Yes, both @Controller together with @RestController are stereotypes. The @Controller is genuinely a specialization of Spring's @Component stereotype annotation. This way that course of report annotated with @Controller volition likewise endure automatically endure detected yesteryear Spring container every bit business office of container's element scanning process.
And, @RestController is a specialization of @Controller for RESTful spider web service. It non solely combines @ResponseBody together with @Controller notation but likewise gives to a greater extent than important to your controller course of report to clearly betoken that it deals amongst RESTful requests.
Spring Framework may likewise exercise this notation to render roughly to a greater extent than useful features related to REST API evolution inwards future.
What is the divergence betwixt @Controller together with @RestController? (answer)
There are many differences between @Controller together with @RestController every bit discussed inwards my before article (see the answer) but the most of import i is that with @RestController y'all acquire the @ResponseBody notation automatically, which way y'all don't demand to separately annotate your handler methods with @ResponseBody annotation. This makes the evolution of RESTful spider web service easier using Spring. You tin meet hither to learn
When do y'all demand @ResponseBody notation inwards Spring MVC? (answer)
The @ResponseBody notation tin endure set on a method to indicates that the render type should endure written guide to the HTTP response trunk (and non placed inwards a Model, or interpreted every bit a persuasion name).
For example:
@RequestMapping(path = "/hello", method = RequestMethod.PUT)
@ResponseBody
public String helloWorld() {
return "Hello World";
}
Alternatively, y'all tin likewise exercise @RestController notation instead of @Controller annotation. This volition take the demand for using @ResponseBody because every bit discussed inwards the previous answer, it comes automatically amongst @RestController annotation.
What does @PathVariable do inwards Spring MVC? Why it's useful inwards REST amongst Spring? (answer)
It's i of the useful annotations from Spring MVC which allows y'all to read values from URI similar query parameter. It's specially useful inwards instance of creating RESTful spider web service using Spring because inwards REST resources identifiers are business office of URI.This questions is commonly asked to experienced Spring MVC developers e.g. four to six years of experience.
For example, inwards the URL http://myapp.com/books/101 if y'all desire to extract 101 the id, so y'all tin use @PathVariable notation of Spring MVC. If y'all are non familiar amongst Spring MVC annotations then Spring MVC For Beginners: Build Java Web App inwards 25 Steps is a proficient house to commencement with.
What is the HTTP condition render code for a successful DELETE statement? (answer)
There is no strict dominion amongst honour to what condition code your REST API should render later a successful DELETE i.e it tin render 200 Ok or 204 No Content. In general, if the DELETE functioning is successful together with the response trunk is empty render 204. If the DELETE asking is successful together with the response trunk is NOT empty, render 200
What does CRUD mean? (answer)
CRUD is a brusque shape of Create, Read, Update together with Delete. In REST API, the POST is used to create a resource, GET is used to read a resource, PUT is used to updated a resources together with DELETE is used to take a resources from the server.This i is roughly other beginner degree Spring MVC questions for 1 to three years experienced programmers
Where do y'all demand @EnableWebMVC? (answer)
The @EnableWebMvc notation is required to enable Spring MVC when Java configuration is used to configure Spring MVC instead of XML. It is equivalent to <mvc: annotation-driven>
It enables back upwards for @Controller-annotated classes that exercise @RequestMapping to map incoming requests to handler methods non already familiar amongst Spring's back upwards for Java configuration, Spring Master Class on Udemy is a proficient house to start.
This may move for a human user but non for REST clients. You demand to shipping them proper condition code e.g. 404 if the resources is non found. That's where y'all tin exercise @ResponseStatus annotation, which allows y'all to shipping custom HTTP condition code along amongst proper mistake message inwards instance of Exception.
In fellowship to exercise it, y'all tin create custom exceptions together with annotated them using @ResponseStatus notation together with proper HTTP condition code together with reason.
When such exceptions are thrown from controller's handler methods together with non handled anywhere else, so appropriate HTTP response amongst the proper HTTP condition code, which y'all receive got laid is sent to the client.
For example, if y'all are writing a RESTful Web Service for a library which provides mass information so y'all tin use @ResponseStatus to create Exception which returns HTTP response code 404 when a mass is non institute instead of Internal Server Error (500), every bit shown below:
@ResponseStatus(value=HttpStatus.NOT_FOUND, reason="No such Book") // 404
public course of report BookNotFoundException extends RuntimeException {
// ...
}
If this Exception is thrown from whatever handler method so HTTP mistake code 404 amongst argue "No such Book" volition endure returned to the client.
Is REST secure? What tin y'all do to secure it? (answer)
This query is generally asked amongst experienced Java programmers e.g. 2 to five years sense amongst both REST together with Spring. Security is a wide term, it could hateful safety of message which is provided yesteryear encryption or access restriction which is provided using authentication together with authorization. REST is commonly non secure but y'all tin secure it yesteryear using Spring security.
At the real to the lowest degree y'all tin enable HTTP basic authentication yesteryear using HTTP inwards your Spring safety configuration file. Similarly, y'all tin expose your REST API using HTTPS if the underlying server supports HTTPS.
Does REST move amongst carry layer safety (TLS)? (answer)
TLS or Transport Layer Security is used for secure communication betwixt customer together with server. It is the successor of SSL (Secure Socket Layer). Since HTTPS tin move amongst both SSL together with TLS, REST tin likewise move amongst TLS.
Actually, REST says anything close Security, it's upwards to the server which implements that. Same RESTful Web Service tin endure accessed using HTTP together with HTTPS if the server supports SSL.
If y'all are using Tomcat, y'all tin meet hither to acquire to a greater extent than close how to enable SSL inwards Tomcat.
Do y'all demand Spring MVC inwards your classpath for developing RESTful Web Service? (answer)
This query is often asked to Java programmers amongst 1 to 2 years of sense inwards Spring. Short respond is Yes, y'all demand Spring MVC inwards your Java application's classpath to develop RESTful spider web services using Spring framework. It's genuinely Spring MVC which provides all useful annotations e.g. @RestController, @ResponseCode, @ResponseBody, @RequestBody, and @PathVariable, thence y'all must spring-mvc.jar or appropriate Maven entry inwards your pom.xml
That's all close roughly frequently asked Spring REST Interview questions for beginners together with experienced Java JEE developers. These questions are likewise real useful to brush upwards your noesis close Spring REST if y'all are going to accept Spring Certification. If y'all demand to a greater extent than questions from Spring certification perspective, y'all volition divulge a lot of query on this theme on David Mayer's Core Spring Simulator, i of the best simulator to transcend Spring certification at the moment.
Other Spring tutorials together with Resources y'all may like
Spring Master Class - Beginner to Expert
Spring Framework 5: Beginner to Guru
5 Free Courses to acquire Core Spring together with Spring Boot
How Spring MVC Frameworks works?
How Basic Authentication plant inwards Spring Security?
What is the Role of DispatcherServlet inwards Spring?
What is divergence between @Service, @Controller, together with @Component inwards Spring
REST With Spring Certification Course yesteryear Baeldung
Thanks for reading this article, if y'all similar this article so delight part amongst your friends together with colleagues. If y'all receive got whatever query which is non answered on this listing so delight drib a comment together with I'll elbow grease my best to divulge an respond for you.
Spring likewise provides customized annotations for RESTful Web Services e.g. @RestController which tin brand your Controller REST aware, so that y'all don't demand to do mutual materials required yesteryear every unmarried REST API e.g. converting the response to JSON.
Influenza A virus subtype H5N1 proficient noesis of Spring Security is likewise mandatory for developing together with safety RESTful Web Services inwards the existent world. Since y'all cannot brand life a non-trivial REST API without security, a proficient noesis of safety basics e.g. HTTP basic authentication, digest authentication, OAuth, together with JWT is real important.
Btw, If y'all are non familiar amongst that concept, I advise y'all acquire through REST amongst Spring together with Learn Spring Security Course to gain roughly sense before your Interview. These ii courses are specially designed to render y'all roughly real-world sense to boost both your noesis together with sense amongst Spring MVC, REST, together with Spring Security.
20 Spring REST Web Service Interview Questions
Here are a twain of often asked questions close using REST Web Services inwards Spring Framework.What does REST stand upwards for? (answer)
REST stands for REpresentational State Transfer, which uses HTTP protocol to shipping information from customer to server e.g. a mass inwards the server tin endure delivered to the customer using JSON or XML.
What is a resource? (answer)
Influenza A virus subtype H5N1 resources is how information is represented inwards REST architecture. By exposing entities every bit the resources it allows a customer to read, write, modify, together with create resources using HTTP methods e.g. GET, POST, PUT, DELETE etc.
What are rubber REST operations? (answer)
REST API uses HTTP methods to perform operations. Some of the HTTP operations which doesn't alteration the resources at the server is known every bit rubber operations e.g. GET together with HEAD. On the other hand, PUT, POST, together with DELETE are dangerous because they alteration the resources on the server.
What are idempotent operations? Why is idempotency important? (answer)
There are roughly HTTP methods e.g. GET which arrive at same response no affair how many times y'all exercise them e.g. sending multiple GET asking to the same URI volition resultant inwards same response without whatever side-effect thence it is known every bit idempotent.
On the other hand, the POST is non idempotent because if y'all shipping multiple POST request, it volition resultant inwards multiple resources creation on the server, but again, PUT is idempotent if y'all are using it to update the resource.
Even, multiple PUT asking to update a resources on a server volition give same terminate result. You tin farther accept RESTful Web Services to acquire to a greater extent than close REST.
What are the advantages of the RestTemplate? (answer)
The RestTemplate course of report is an implementation of Template method pattern inwards Spring framework. Similar to other pop template classes e.g. JdbcTemplate or JmsTempalte, it likewise simplifies the interaction amongst RESTful Web Services on the customer side. You tin exercise it to swallow a RESTful Web Servicer real easily every bit shown inwards this example.
Which HTTP methods does REST use? (answer)
REST tin exercise whatever HTTP methods but the most pop ones are GET for retrieving a resource, POST for creating a resource, PUt for updating resources together with DELETE for removing a resources from the server.
What is an HttpMessageConverter inwards Spring REST? (answer)
An HttpMessageConverter is a Strategy interface that specifies a converter that tin convert from together with to HTTP requests together with responses. Spring REST uses this interface to convert HTTP response to diverse formats e.g. JSON or XML.
Each HttpMessageConverter implementation has i or several MIME Types associated amongst it. Spring uses the "Accept" header to create upwards one's heed the content type customer is expecting.
It volition so elbow grease to divulge a registered HTTPMessageConverter that is capable of treatment that specific content-type together with exercise it to convert the response into that format before sending to the client.
How to create a custom implementation of HttpMessageConverter to back upwards a novel type of request/responses? (answer)
You but demand to create an implementation of AbstractHttpMessageConverter together with register it using the WebMvcConfigurerAdapter#extendMessageConverters() method amongst the classes which generate a novel type of request/response.
Is REST commonly stateless? (answer)
Yes, REST API should endure stateless because it is based on HTTP which is likewise stateless. Influenza A virus subtype H5N1 Request inwards REST API should incorporate all the details required it to procedure i.e. it should non rely on previous or adjacent asking or roughly information maintained at the server terminate e.g. Sessions. REST specification set a constraint to acquire far stateless together with y'all should drib dead on that inwards heed spell designing your REST API.
What does @RequestMapping notation do? (answer)
The @RequestMapping notation is used to map spider web requests to Spring Controller methods. You tin map asking based upon HTTP methods e.g. GET together with POST together with diverse other parameters. For examples, if y'all are developing RESTful Web Service using Spring so y'all tin exercise produces together with consumes belongings along amongst media type notation to betoken that this method is solely used to arrive at or consumers JSON every bit shown below:
@RequestMapping (method = RequestMethod.POST, consumes="application/json") public Book save(@RequestBody Book aBook) { return bookRepository.save(aBook); }You tin similarly create other handler methods to arrive at JSON or XML. If y'all are non familiar amongst these annotations so I advise y'all bring together Spring MVC For Beginners course of report on Udemy to acquire from scratch.
Is @Controller a stereotype? Is @RestController a stereotype? (answer)
Yes, both @Controller together with @RestController are stereotypes. The @Controller is genuinely a specialization of Spring's @Component stereotype annotation. This way that course of report annotated with @Controller volition likewise endure automatically endure detected yesteryear Spring container every bit business office of container's element scanning process.
And, @RestController is a specialization of @Controller for RESTful spider web service. It non solely combines @ResponseBody together with @Controller notation but likewise gives to a greater extent than important to your controller course of report to clearly betoken that it deals amongst RESTful requests.
Spring Framework may likewise exercise this notation to render roughly to a greater extent than useful features related to REST API evolution inwards future.
What is the divergence betwixt @Controller together with @RestController? (answer)
There are many differences between @Controller together with @RestController every bit discussed inwards my before article (see the answer) but the most of import i is that with @RestController y'all acquire the @ResponseBody notation automatically, which way y'all don't demand to separately annotate your handler methods with @ResponseBody annotation. This makes the evolution of RESTful spider web service easier using Spring. You tin meet hither to learn
When do y'all demand @ResponseBody notation inwards Spring MVC? (answer)
The @ResponseBody notation tin endure set on a method to indicates that the render type should endure written guide to the HTTP response trunk (and non placed inwards a Model, or interpreted every bit a persuasion name).
For example:
@RequestMapping(path = "/hello", method = RequestMethod.PUT)
@ResponseBody
public String helloWorld() {
return "Hello World";
}
Alternatively, y'all tin likewise exercise @RestController notation instead of @Controller annotation. This volition take the demand for using @ResponseBody because every bit discussed inwards the previous answer, it comes automatically amongst @RestController annotation.
What does @PathVariable do inwards Spring MVC? Why it's useful inwards REST amongst Spring? (answer)
It's i of the useful annotations from Spring MVC which allows y'all to read values from URI similar query parameter. It's specially useful inwards instance of creating RESTful spider web service using Spring because inwards REST resources identifiers are business office of URI.This questions is commonly asked to experienced Spring MVC developers e.g. four to six years of experience.
For example, inwards the URL http://myapp.com/books/101 if y'all desire to extract 101 the id, so y'all tin use @PathVariable notation of Spring MVC. If y'all are non familiar amongst Spring MVC annotations then Spring MVC For Beginners: Build Java Web App inwards 25 Steps is a proficient house to commencement with.
What is the HTTP condition render code for a successful DELETE statement? (answer)
There is no strict dominion amongst honour to what condition code your REST API should render later a successful DELETE i.e it tin render 200 Ok or 204 No Content. In general, if the DELETE functioning is successful together with the response trunk is empty render 204. If the DELETE asking is successful together with the response trunk is NOT empty, render 200
What does CRUD mean? (answer)
CRUD is a brusque shape of Create, Read, Update together with Delete. In REST API, the POST is used to create a resource, GET is used to read a resource, PUT is used to updated a resources together with DELETE is used to take a resources from the server.This i is roughly other beginner degree Spring MVC questions for 1 to three years experienced programmers
Where do y'all demand @EnableWebMVC? (answer)
The @EnableWebMvc notation is required to enable Spring MVC when Java configuration is used to configure Spring MVC instead of XML. It is equivalent to <mvc: annotation-driven>
It enables back upwards for @Controller-annotated classes that exercise @RequestMapping to map incoming requests to handler methods non already familiar amongst Spring's back upwards for Java configuration, Spring Master Class on Udemy is a proficient house to start.
When do y'all demand @ResponseStatus notation inwards Spring MVC? (answer)
Influenza A virus subtype H5N1 proficient questions for three to five years experienced boundary developers. The @ResponseStatus notation is required during mistake treatment inwards Spring MVC together with REST. Normally when an mistake or exception is thrown at server side, spider web server render a blanket HTTP condition code 500 - Internal server error.This may move for a human user but non for REST clients. You demand to shipping them proper condition code e.g. 404 if the resources is non found. That's where y'all tin exercise @ResponseStatus annotation, which allows y'all to shipping custom HTTP condition code along amongst proper mistake message inwards instance of Exception.
In fellowship to exercise it, y'all tin create custom exceptions together with annotated them using @ResponseStatus notation together with proper HTTP condition code together with reason.
When such exceptions are thrown from controller's handler methods together with non handled anywhere else, so appropriate HTTP response amongst the proper HTTP condition code, which y'all receive got laid is sent to the client.
For example, if y'all are writing a RESTful Web Service for a library which provides mass information so y'all tin use @ResponseStatus to create Exception which returns HTTP response code 404 when a mass is non institute instead of Internal Server Error (500), every bit shown below:
@ResponseStatus(value=HttpStatus.NOT_FOUND, reason="No such Book") // 404
public course of report BookNotFoundException extends RuntimeException {
// ...
}
If this Exception is thrown from whatever handler method so HTTP mistake code 404 amongst argue "No such Book" volition endure returned to the client.
Is REST secure? What tin y'all do to secure it? (answer)
This query is generally asked amongst experienced Java programmers e.g. 2 to five years sense amongst both REST together with Spring. Security is a wide term, it could hateful safety of message which is provided yesteryear encryption or access restriction which is provided using authentication together with authorization. REST is commonly non secure but y'all tin secure it yesteryear using Spring security.
At the real to the lowest degree y'all tin enable HTTP basic authentication yesteryear using HTTP inwards your Spring safety configuration file. Similarly, y'all tin expose your REST API using HTTPS if the underlying server supports HTTPS.
Does REST move amongst carry layer safety (TLS)? (answer)
TLS or Transport Layer Security is used for secure communication betwixt customer together with server. It is the successor of SSL (Secure Socket Layer). Since HTTPS tin move amongst both SSL together with TLS, REST tin likewise move amongst TLS.
Actually, REST says anything close Security, it's upwards to the server which implements that. Same RESTful Web Service tin endure accessed using HTTP together with HTTPS if the server supports SSL.
If y'all are using Tomcat, y'all tin meet hither to acquire to a greater extent than close how to enable SSL inwards Tomcat.
Do y'all demand Spring MVC inwards your classpath for developing RESTful Web Service? (answer)
This query is often asked to Java programmers amongst 1 to 2 years of sense inwards Spring. Short respond is Yes, y'all demand Spring MVC inwards your Java application's classpath to develop RESTful spider web services using Spring framework. It's genuinely Spring MVC which provides all useful annotations e.g. @RestController, @ResponseCode, @ResponseBody, @RequestBody, and @PathVariable, thence y'all must spring-mvc.jar or appropriate Maven entry inwards your pom.xml
That's all close roughly frequently asked Spring REST Interview questions for beginners together with experienced Java JEE developers. These questions are likewise real useful to brush upwards your noesis close Spring REST if y'all are going to accept Spring Certification. If y'all demand to a greater extent than questions from Spring certification perspective, y'all volition divulge a lot of query on this theme on David Mayer's Core Spring Simulator, i of the best simulator to transcend Spring certification at the moment.
Other Spring tutorials together with Resources y'all may like
Spring Master Class - Beginner to Expert
Spring Framework 5: Beginner to Guru
5 Free Courses to acquire Core Spring together with Spring Boot
How Spring MVC Frameworks works?
How Basic Authentication plant inwards Spring Security?
What is the Role of DispatcherServlet inwards Spring?
What is divergence between @Service, @Controller, together with @Component inwards Spring
REST With Spring Certification Course yesteryear Baeldung
Thanks for reading this article, if y'all similar this article so delight part amongst your friends together with colleagues. If y'all receive got whatever query which is non answered on this listing so delight drib a comment together with I'll elbow grease my best to divulge an respond for you.
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