Serious Java Spring Mistakes You Must Avoid

Spring Boot Pitfalls That Will Destroy Your Production Application

Photo by Luca Bravo on Unsplash

Spring Boot is powerful but with great power comes great chances to mess things up.

If you’re building real-world Java Spring applications, here are common but serious mistakes many developers make, especially beginners. These can slow down your app, introduce bugs, or make your code unmaintainable.

Putting Business Logic in Controllers

In Spring, your @RestController is just an entry point. Its job is simple:

• Accept the HTTP request
• Validate input (maybe)
• Call a service to do the actual work
• Return the response

That’s it. Nothing more.

But beginners often write all the logic right in the controller - validation, processing, saving to DB, etc.

@RestController
public class OrderController {

    @Autowired
    private OrderRepository orderRepository;

    @PostMapping("/order")
    public String placeOrder(@RequestBody Order order) {
        // Business rule inside controller
        if (order.getAmount() > 10000) {
            throw new IllegalArgumentException("Amount too large")…