How do you handle exceptions globally in Spring Boot?

In Spring Boot, global exception handling allows you to manage all application errors in one centralized place instead of writing try-catch blocks in every controller.

👉 This is achieved using @ControllerAdvice and @ExceptionHandler.

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Why Global Exception Handling is Needed

Without global handling:

• Repeated try-catch blocks

• Inconsistent error responses

• Difficult to maintain

With global handling:

• Centralized error management

• Clean and readable code

• Consistent API responses

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Key Annotations

1. @ControllerAdvice

• Used to define a global exception handler

• Applies to all controllers

2. @ExceptionHandler

• Handles specific exceptions

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Example Implementation

Step 1: Create Global Exception Handler

@ControllerAdvice
public class GlobalExceptionHandler {

    @ExceptionHandler(Exception.class)
    public ResponseEntity<String> handleException(Exception ex) {
        return new ResponseEntity<>("Something went wrong: " + ex.getMessage(), HttpStatus.INTERNAL_SERVER_ERROR);
    }
}

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Step 2: Handle Specific Exceptions

@ExceptionHandler(NullPointerException.class)
public ResponseEntity<String> handleNullPointer(NullPointerException ex) {
    return new ResponseEntity<>("Null value found!", HttpStatus.BAD_REQUEST);
}

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Custom Exception Example

public class ResourceNotFoundException extends RuntimeException {
    public ResourceNotFoundException(String message) {
        super(message);
    }
}

Handler:

@ExceptionHandler(ResourceNotFoundException.class)
public ResponseEntity<String> handleResourceNotFound(ResourceNotFoundException ex) {
    return new ResponseEntity<>(ex.getMessage(), HttpStatus.NOT_FOUND);
}

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Returning Custom Error Response

public class ErrorResponse {
    private String message;
    private int status;
}

@ExceptionHandler(Exception.class)
public ResponseEntity<ErrorResponse> handleException(Exception ex) {
    ErrorResponse error = new ErrorResponse(ex.getMessage(), 500);
    return new ResponseEntity<>(error, HttpStatus.INTERNAL_SERVER_ERROR);
}

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Advantages of Global Exception Handling

• Centralized logic

• Cleaner controllers

• Better API design

• Easy maintenance

• Consistent error structure

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Best Practices

• Handle specific exceptions first

• Create custom exceptions

• Return meaningful error messages

• Use proper HTTP status codes

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Conclusion

Global exception handling in Spring Boot using @ControllerAdvice and @ExceptionHandler helps build clean, maintainable, and production-ready applications by managing errors in a centralized and consistent way.

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