Problem Details for standard error format in Spring Boot - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What is the output of this Spring Boot error response?

Given a REST controller that throws a ResponseStatusException with status 404 and a custom message, what will the JSON error response contain when using Spring Boot's default Problem Details format?

Spring Boot

throw new ResponseStatusException(HttpStatus.NOT_FOUND, "User not found");

A {"error":"Not Found","message":"User not found","status":404}

B {"type":"about:blank","title":"Not Found","status":404,"detail":"User not found"}

C {"code":404,"error":"User not found"}

D {"status":404,"error":"Not Found","description":"User not found"}

💡 Hint

Look for the standard keys defined by RFC 7807 in the JSON response.

Spring Boot uses the Problem Details format (RFC 7807) by default for error responses. It includes keys like type, title, status, and detail.

📝 Syntax

intermediate

Which code snippet correctly creates a Problem Details response in Spring Boot?

You want to return a custom Problem Details JSON response with status 400 and a detail message. Which code snippet correctly uses Spring Boot's ProblemDetail class?

A ProblemDetail pd = new ProblemDetail(400, "Invalid input"); return ResponseEntity.badRequest().body(pd);

B ProblemDetail pd = ProblemDetail.create(400, "Invalid input"); return ResponseEntity.status(400).body(pd);

C ProblemDetail pd = ProblemDetail.forStatusAndDetail(HttpStatus.BAD_REQUEST, "Invalid input"); return ResponseEntity.status(pd.getStatus()).body(pd);

D ProblemDetail pd = ProblemDetail.of(HttpStatus.BAD_REQUEST, "Invalid input"); return ResponseEntity.badRequest().body(pd);

💡 Hint

Check the official Spring Boot 3 method to create ProblemDetail instances.

The ProblemDetail.forStatusAndDetail static method is the correct way to create a ProblemDetail with status and detail.

🔧 Debug

advanced

Why does this custom error handler not return Problem Details JSON?

A developer wrote this exception handler method but the response is plain text instead of Problem Details JSON. What is the likely cause?

Spring Boot

@ExceptionHandler(IllegalArgumentException.class)
@ResponseStatus(HttpStatus.BAD_REQUEST)
public String handleBadRequest(IllegalArgumentException ex) {
    return ex.getMessage();
}

A The method lacks @ResponseBody annotation to serialize the return value.

B The @ResponseStatus annotation is missing the produces attribute for JSON.

C The exception handler must return ResponseEntity<ProblemDetail> to produce JSON.

D The method returns a String, so Spring treats it as plain text instead of ProblemDetail JSON.

💡 Hint

Consider how Spring decides the response content type based on return type.

Returning a String causes Spring to treat the response as plain text. To return Problem Details JSON, the method should return a ProblemDetail object or ResponseEntity<ProblemDetail>.

🧠 Conceptual

advanced

What is the purpose of the 'type' field in Problem Details JSON?

In the Problem Details standard error format, what does the type field represent?

A A URI reference that identifies the problem type, providing human-readable documentation.

B The timestamp when the error occurred.

C A short summary of the error message.

D The HTTP status code of the error.

💡 Hint

Think about how clients can learn more about the error type.

The type field is a URI that points to documentation about the error type, helping clients understand the problem.

❓ state_output

expert

What is the JSON output of this Spring Boot controller advice method?

Given this controller advice method, what JSON will be returned when a NullPointerException occurs?

Spring Boot

@ControllerAdvice
public class GlobalExceptionHandler {
    @ExceptionHandler(NullPointerException.class)
    public ResponseEntity<ProblemDetail> handleNullPointer(NullPointerException ex) {
        ProblemDetail pd = ProblemDetail.forStatusAndDetail(HttpStatus.INTERNAL_SERVER_ERROR, "Null value encountered");
        pd.setType(URI.create("https://example.com/errors/null-pointer"));
        pd.setTitle("Null Pointer Exception");
        return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body(pd);
    }
}

A {"type":"https://example.com/errors/null-pointer","title":"Null Pointer Exception","status":500,"detail":"Null value encountered"}

B {"error":"Null Pointer Exception","message":"Null value encountered","status":500}

C {"status":500,"title":"Null Pointer Exception","description":"Null value encountered"}

D {"type":"about:blank","title":"Internal Server Error","status":500,"detail":"Null value encountered"}

💡 Hint

Check how the ProblemDetail fields are set explicitly in the method.

The method sets a custom type URI and title, so the JSON reflects those values along with status and detail.