Exception Handling in Spring Boot Applications

Exception handling is a crucial part of any web application. In Spring Boot, a robust exception handling mechanism ensures that your application responds gracefully to errors, improving user experience and debugging efficiency. With built-in support and customizable tools, Spring Boot makes exception handling both simple and powerful.

Why Exception Handling Matters

In a typical application, exceptions like NullPointerException, EntityNotFoundException, or MethodArgumentNotValidException can occur. Without proper handling, these can expose sensitive stack traces or return confusing messages to clients. Instead, a clean and consistent error response format should be used.

Default Exception Handling

Spring Boot automatically handles many common exceptions and returns appropriate HTTP status codes. For example:

@Valid or @Validated failures return 400 Bad Request

Missing resources return 404 Not Found

However, you often need custom logic, especially for business exceptions or validation errors.

Using @ControllerAdvice for Global Exception Handling

@ControllerAdvice allows you to handle exceptions globally, in one centralized place.

@RestControllerAdvice

public class GlobalExceptionHandler {

    @ExceptionHandler(ResourceNotFoundException.class)

    public ResponseEntity<String> handleNotFound(ResourceNotFoundException ex) {

        return new ResponseEntity<>(ex.getMessage(), HttpStatus.NOT_FOUND);

    }

    @ExceptionHandler(MethodArgumentNotValidException.class)

    public ResponseEntity<Map<String, String>> handleValidationErrors(MethodArgumentNotValidException ex) {

        Map<String, String> errors = new HashMap<>();

        ex.getBindingResult().getFieldErrors().forEach(error ->

            errors.put(error.getField(), error.getDefaultMessage())

        );

        return new ResponseEntity<>(errors, HttpStatus.BAD_REQUEST);

    }

    @ExceptionHandler(Exception.class)

    public ResponseEntity<String> handleGeneric(Exception ex) {

        return new ResponseEntity<>("Something went wrong: " + ex.getMessage(), HttpStatus.INTERNAL_SERVER_ERROR);

    }

}

Creating Custom Exceptions

Define your own exceptions for better clarity and control:

public class ResourceNotFoundException extends RuntimeException {

    public ResourceNotFoundException(String message) {

        super(message);

    }

}

Then throw it from your service or controller as needed.

Final Thoughts

Exception handling in Spring Boot promotes clean code, modular error management, and user-friendly API responses. By using @ControllerAdvice and custom exceptions, you can separate error-handling logic and ensure your application remains maintainable, secure, and professional. Robust exception handling isn't just good practice—it’s a must for production-ready applications. 

Learn  Full Stack Java Training

Dependency Injection and Inversion of Control

Spring Boot Auto-Configuration Explained

Building CRUD APIs with Spring Boot and JPA

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