@PutMapping and @DeleteMapping in Spring Boot - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What happens when a @PutMapping method returns void?

Consider a Spring Boot REST controller method annotated with @PutMapping that returns void. What is the HTTP response status code by default when this method completes successfully?

Spring Boot

    @PutMapping("/items/{id}")
    public void updateItem(@PathVariable String id, @RequestBody Item item) {
        // update logic
    }

A HTTP 200 OK with empty body

B HTTP 204 No Content

C HTTP 201 Created

D HTTP 404 Not Found

💡 Hint

Think about what HTTP status means no content is returned.

When a @PutMapping method returns void, Spring Boot by default sends HTTP 200 OK with an empty body, indicating the request was successful but no content is returned.

📝 Syntax

intermediate

Identify the syntax error in this @DeleteMapping method

Which option correctly fixes the syntax error in this @DeleteMapping method?

Spring Boot

    @DeleteMapping("/users/{id}")
    public ResponseEntity deleteUser(@PathVariable Long id) {
        userService.delete(id);
        return ResponseEntity.ok().build();
    }

A Remove the return statement

B Change @DeleteMapping to @GetMapping

C Add a semicolon after userService.delete(id);

D Change @PathVariable Long id to @RequestParam Long id

💡 Hint

Look for missing punctuation in Java statements.

The method call userService.delete(id) is missing a semicolon at the end, causing a syntax error.

❓ state_output

advanced

What is the response body of this @PutMapping method?

Given the following @PutMapping method, what will be the HTTP response body when updating an item successfully?

Spring Boot

    @PutMapping("/products/{id}")
    public ResponseEntity<Product> updateProduct(@PathVariable Long id, @RequestBody Product product) {
        Product updated = productService.update(id, product);
        return ResponseEntity.ok(updated);
    }

A The updated Product object serialized as JSON

B An empty response body with HTTP 204 status

C A plain text message 'Product updated successfully'

D HTTP 404 error if product not found

💡 Hint

Look at what is returned inside ResponseEntity.ok()

The method returns ResponseEntity.ok(updated), so the updated Product object is serialized to JSON and sent in the response body with HTTP 200 status.

🔧 Debug

advanced

Why does this @DeleteMapping method cause a 405 Method Not Allowed error?

A client sends a DELETE request to /orders/123 but receives a 405 Method Not Allowed error. Which option explains the most likely cause?

Spring Boot

    @GetMapping("/orders/{id}")
    public Order getOrder(@PathVariable Long id) {
        return orderService.findById(id);
    }

A The orderService.findById method throws an exception

B There is no @DeleteMapping method for /orders/{id}, only @GetMapping exists

C The client request method is incorrect and should be GET

D The @GetMapping method is missing @DeleteMapping annotation

💡 Hint

Check which HTTP methods the controller supports for the URL.

The controller only has a @GetMapping for /orders/{id}, so DELETE requests to that URL are not handled, causing 405 error.

🧠 Conceptual

expert

Which statement about @PutMapping and @DeleteMapping is true?

Select the correct statement about the behavior of @PutMapping and @DeleteMapping in Spring Boot controllers.

A @PutMapping and @DeleteMapping cannot be used together in the same controller class.

B @PutMapping always creates new resources; @DeleteMapping returns the deleted resource in the response body.

C @PutMapping and @DeleteMapping require the HTTP request body to be empty.

D @PutMapping is idempotent and typically used to update resources; @DeleteMapping is idempotent and used to remove resources.

💡 Hint

Think about HTTP method semantics and REST principles.

@PutMapping corresponds to HTTP PUT which is idempotent and used for updating resources. @DeleteMapping corresponds to HTTP DELETE which is also idempotent and used to delete resources.