Common Spring Boot Mistakes and How to Fix Them

Spring Boot simplifies Java development, but improper usage can lead to performance bottlenecks and maintainability issues. Whether you’re building a fintech application like a core banking system or an e-commerce platform, avoiding these mistakes will save you hours of debugging. Let’s explore the most frequent Spring Boot pitfalls and their solutions.

1. Overusing Spring Boot Annotations

Keywords: Spring Boot annotations, @Component misuse, @Autowired best practices

The Problem:

Annotations like @Component, @Autowired, and @RestController are often misused, leading to unnecessary complexity.

Example 1: Unnecessary @Component

@Component // ❌ Avoid for stateless utilities  
public class DateUtil {  
    public static String formatDate(...) { ... }  
}  

Fix: Remove @Component for utility classes.

Example 2: Redundant @ResponseBody

@RestController  
public class AccountController {  
    @GetMapping("/accounts")  
    @ResponseBody // ❌ Not needed in @RestController  
    public List<Account> getAccounts() { ... }  
}  

Fix: @RestController already includes @ResponseBody.

Best Practices:

• Use constructor injection instead of field injection.
• Prefer @Service, @Repository, and @Controller over generic @Component.

2. Poor Property Management

Keywords: Spring Boot properties, environment configuration, YAML best practices

The Problem:

Hardcoded configurations make deployments inflexible.

Mistake:

@Value("jdbc:mysql://localhost:3306/dev_db") // ❌ Hardcoded URL  
private String dbUrl;  

Fix: Externalize configurations in application.properties or application.yml:

# application-dev.properties  
spring.datasource.url = jdbc:mysql://localhost:3306/dev_corebanking  

Pro Tip: Use Spring Profiles for environment-specific configurations:

java -jar app.jar --spring.profiles.active=prod  

3. Ignoring Global Exception Handling

Keywords: Spring Boot exception handling, @ControllerAdvice, custom exceptions

The Problem:

Scattered try-catch blocks make error handling inconsistent.

Mistake:

catch (Exception e) {  
    throw new RuntimeException("Error"); // ❌ Unhelpful error message  
}  

Fix: Use @ControllerAdvice for centralized exception handling:

@ControllerAdvice  
public class GlobalExceptionHandler {  
    @ExceptionHandler(AccountNotFoundException.class)  
    public ResponseEntity<String> handleException(AccountNotFoundException ex) {  
        return ResponseEntity.status(HttpStatus.NOT_FOUND).body(ex.getMessage());  
    }  
}  

Best Practices:

• Create custom exceptions like InsufficientFundsException.
• Maintain uniform error responses across APIs.

4. Inefficient Logging Practices

Keywords: Spring Boot logging, SLF4J, Logback configuration

The Problem:

Unstructured logging leads to poor debugging experiences.

Bad Example:

logger.info("Processing..."); // ❌ Too vague  

Good Example:

logger.debug("Processing transaction ID: {}", id); // ✅ More useful  

Configure Log Levels:

logging.level.com.yourbank = DEBUG  
logging.level.org.springframework = ERROR  

5. Overexposing Internal APIs

Keywords: Java encapsulation, Spring Boot security

The Problem:

Making classes/methods public unnecessarily exposes them.

Fix:

• Use package-private access where possible.
• Organize code into feature-based packages (e.g., com.corebanking.account).

6. Field Injection Overuse

Keywords: Spring Boot dependency injection, constructor vs field injection

The Problem:

@Autowired on fields makes testing harder.

Mistake:

@Autowired // ❌ Field injection  
private AccountService accountService;  

Fix: Use constructor injection:

private final AccountService accountService;  
public AccountController(AccountService accountService) {  
    this.accountService = accountService;  
}  

7. Unnecessary Interfaces

Keywords: Spring Boot interfaces, single implementation

The Problem:

Single-implementation interfaces add unnecessary complexity.

Mistake:

public interface AccountService { ... } // ❌ Only 1 implementation  
public class AccountServiceImpl implements AccountService { ... }  

Fix: Use a concrete class unless multiple implementations exist.

8. Non-RESTful API Design

Keywords: REST API design, Spring Boot endpoints

The Problem:

Inconsistent API endpoints reduce maintainability.

Fix: Follow REST conventions:

@GetMapping("/accounts/{id}") // ✅ Clean and intuitive  
public Account getAccount(@PathVariable Long id) { ... }  

9. Ignoring Transaction Management

Keywords: Spring Boot transactions, @Transactional

The Problem:

Forgetting @Transactional can cause data inconsistencies.

Fix: Use @Transactional in service methods:

@Transactional  
public void transferFunds(...) { ... }  

FAQs: Spring Boot Best Practices

Q1: What’s the difference between @Controller and @RestController?
A: @RestController is a combination of @Controller and @ResponseBody, designed for REST APIs.

Q2: How to activate a Spring profile?
A: Use --spring.profiles.active=dev or set it in application.properties.

Q3: Why is constructor injection preferred?
A: It promotes immutability and improves testability.

Final Thoughts

By avoiding these Spring Boot mistakes, you’ll build more maintainable, scalable applications. Focus on clean code, proper annotations, and efficient API design.

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