Spring Boot Validation and Error Handling

Question 1

Which annotation triggers Bean Validation on a method parameter in a Spring MVC controller?

Accepted Answer

@Valid

Answer

@Valid (from javax/jakarta.validation) triggers Bean Validation cascading on the annotated parameter when used in controller method signatures.

Question 2

What is the key difference between @NotEmpty and @NotBlank in Bean Validation?

Accepted Answer

@NotEmpty rejects null and empty strings; @NotBlank also rejects strings containing only whitespace

Answer

@NotEmpty rejects null and empty strings (""), while @NotBlank additionally rejects strings that consist solely of whitespace characters.

Question 3

When a controller method parameter annotated with @Valid fails validation, which exception is thrown by Spring MVC by default?

Accepted Answer

MethodArgumentNotValidException

Answer

Spring MVC throws MethodArgumentNotValidException when @Valid validation on a @RequestBody parameter fails, wrapping the BindingResult with all constraint violations.

Question 4

Which interface must be added alongside the BindingResult parameter in a controller method to capture validation errors without throwing an exception?

Accepted Answer

The BindingResult parameter must immediately follow the @Valid parameter

Answer

Spring MVC requires the BindingResult parameter to immediately follow the @Valid/@Validated parameter so that validation errors are captured rather than propagated as exceptions.

Question 5

What does the @ControllerAdvice annotation do in the context of exception handling?

Accepted Answer

It designates a class to handle exceptions globally across all controllers

Answer

@ControllerAdvice designates a class whose @ExceptionHandler, @InitBinder, and @ModelAttribute methods apply globally across all @Controller classes in the application.

Spring Boot Practice Test

Spring Boot Practice Test

Spring Boot Validation and Error Handling