Spring Boot Exception Handling

Question Variations

"Why use controller advice instead of local try/catch blocks?"
"How do you avoid leaking exception details?"
"When would you return a `ProblemDetail`?"

Why This Is Asked

Centralized exception mapping tests secure API design and Spring MVC’s error-handling mechanisms.

Key Concepts

@RestControllerAdvice centralizes controller exception responses.
Map expected application exceptions to client-safe HTTP status codes.
Preserve detailed diagnostics in logs, not client responses.
ProblemDetail supports standardized error bodies.

Question Variations

“Why use controller advice instead of local try/catch blocks?”
“How do you avoid leaking exception details?”
“When would you return a ProblemDetail?”

Answers by Technology

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Expected Answer (Spring Boot 4.1.0 / Java 17+)

Use @RestControllerAdvice with @ExceptionHandler methods to map application exceptions to consistent, client-safe responses. Return precise status codes for expected failures, log unexpected failures with request context, and never expose stack traces or database errors. ProblemDetail provides a standard structured response body for HTTP API errors.

Why It Matters

Central handling keeps clients predictable and prevents sensitive internal details from escaping.

Code Example

@RestControllerAdvice
class ApiErrors {
  @ExceptionHandler(IllegalArgumentException.class)
  ProblemDetail invalid(IllegalArgumentException error) {
    return ProblemDetail.forStatusAndDetail(HttpStatus.BAD_REQUEST, "Invalid request");
  }
}

Common Mistakes

Catching Exception in every controller: Error policy becomes inconsistent and repetitive.
Returning error.getMessage() for unknown failures: Internal details may leak.

Follow-up Questions

Why use ProblemDetail? (Answer: It provides a standardized HTTP error representation.)
Where should logging happen? (Answer: Centrally with safe request context.)