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

@Validate

Answer

@Constraint

Answer

@NotNull

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 checks for null only; @NotBlank checks for whitespace

Answer

They are identical and interchangeable

Answer

@NotBlank applies only to numeric fields; @NotEmpty applies to collections

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

ConstraintViolationException

Answer

ValidationException

Answer

BindException

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

BindingResult must be declared before the @Valid parameter

Answer

BindingResult must be a separate method annotated with @ErrorHandler

Answer

BindingResult is not supported in Spring Boot controllers

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

It marks a class as a Spring component that provides controller-level configuration

Answer

It enables AOP advice on controller method return values

Answer

It registers a filter that intercepts controller exceptions

Question 6

How do you create a custom constraint annotation in Bean Validation?

Accepted Answer

Annotate the annotation with @Constraint(validatedBy=...) and implement ConstraintValidator

Answer

Extend AbstractConstraint and override the validate() method

Answer

Implement Validator<T> and register it as a Spring bean

Answer

Use @CustomValidator on the field and provide a validation class name

Question 7

Which annotation is used to define validation groups, and how are groups specified on a constraint?

Accepted Answer

groups={} attribute on the constraint annotation; activated via @Validated(Group.class) on the controller

Answer

@GroupSequence on the constraint; groups are listed as an attribute

Answer

Validation groups require a separate XML configuration file

Answer

@Profile annotation is used to switch validation groups