Spring Boot Building RESTful Services 3

Question 1

What is the role of the @PathVariable annotation in Spring REST controllers?

Accepted Answer

Binds a URI template variable to a method parameter

Answer

@PathVariable extracts values from URI template placeholders (e.g., /users/{id}) and binds them to method parameters.

Question 2

Which Spring Boot property disables the default error whitelabel page for REST APIs?

Accepted Answer

server.error.whitelabel.enabled=false

Answer

Setting server.error.whitelabel.enabled=false in application.properties disables the default HTML error page, allowing custom error handling.

Question 3

What HTTP status code should a REST API return when a client sends a request with an unsupported Content-Type?

Accepted Answer

415 Unsupported Media Type

Answer

HTTP 415 Unsupported Media Type indicates that the server cannot process the request's payload format as specified by the Content-Type header.

Question 4

In a Spring REST API, what annotation would you use to validate that a request body field is not blank?

Accepted Answer

@NotBlank

Answer

@NotBlank (from javax.validation) ensures the field is not null and contains at least one non-whitespace character, failing if it's an empty or whitespace-only string.

Question 5

Which interface should a custom Spring REST error response class implement to integrate with Spring's default error handling mechanism?

Accepted Answer

ErrorResponse

Answer

Implementing ErrorResponse allows a custom exception to carry RFC 9457 Problem Details fields, which Spring's exception handlers can serialize automatically.

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Spring Boot Practice Test

Spring Boot Building RESTful Services 3