Returning different status codes in Spring Boot - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What HTTP status code does this Spring Boot controller return?

Consider this Spring Boot controller method. What status code will the client receive when calling this endpoint?

Spring Boot

import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class MyController {
    @GetMapping("/check")
    public ResponseEntity<String> check() {
        return ResponseEntity.status(201).body("Created");
    }
}

A 200 OK

B 404 Not Found

C 201 Created

D 500 Internal Server Error

💡 Hint

Look at the status method used in ResponseEntity.

The method uses ResponseEntity.status(201) which sets the HTTP status code to 201 Created.

📝 Syntax

intermediate

Which option correctly returns a 404 status with a message in Spring Boot?

You want to return a 404 Not Found status with a message "User not found". Which code snippet is correct?

A return ResponseEntity.status(404).body("User not found");

B return ResponseEntity.notFound().body("User not found");

C return ResponseEntity.status(HttpStatus.NOT_FOUND, "User not found");

D return new ResponseEntity<>("User not found", 404);

💡 Hint

Check the ResponseEntity methods and constructors.

Option A correctly uses ResponseEntity.status(404).body(...) to set status and body. Option A is invalid because notFound() returns a ResponseEntity without a body() method. Option A is invalid syntax as there is no status(HttpStatus, Object) method. Option A uses invalid constructor arguments (expects HttpStatus, not int).

🔧 Debug

advanced

Why does this Spring Boot controller always return 200 OK instead of 400 Bad Request?

Look at this controller method. It tries to return 400 Bad Request on error but always returns 200 OK. Why?

Spring Boot

import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class ErrorController {
    @GetMapping("/error")
    public ResponseEntity<String> error(boolean hasError) {
        if (hasError) {
            return ResponseEntity.status(400).body("Bad Request");
        }
        return ResponseEntity.ok("All good");
    }
}

A The 400 ResponseEntity is created but not returned from the method.

B ResponseEntity.status(400) is invalid and defaults to 200.

C The method parameter 'hasError' is ignored by Spring Boot.

D The method must throw an exception to return 400 status.

💡 Hint

Check if the method returns the ResponseEntity created inside the if block.

The method creates a ResponseEntity with status 400 but does not return it. The method always returns ResponseEntity.ok("All good"), so status 200 is sent.

❓ state_output

advanced

What is the HTTP status code when this Spring Boot controller returns null body with 204 status?

This controller returns ResponseEntity with status 204 No Content and a null body. What will the client receive?

Spring Boot

import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class NoContentController {
    @GetMapping("/nocontent")
    public ResponseEntity<String> noContent() {
        return ResponseEntity.noContent().build();
    }
}

A 500 Internal Server Error

B 204 No Content with 'null' string body

C 200 OK with empty body

D 204 No Content with empty body

💡 Hint

Check what ResponseEntity.noContent().build() does.

ResponseEntity.noContent().build() returns a response with status 204 and no body content, so the client receives 204 No Content with empty body.

🧠 Conceptual

expert

Which option correctly demonstrates returning different status codes based on input in Spring Boot?

You want a controller method that returns 200 OK with "Success" if input is true, and 404 Not Found with "Not Found" if false. Which code snippet correctly implements this?

A

public ResponseEntity<String> check(boolean input) {
    return input ? ResponseEntity.ok("Success") : ResponseEntity.notFound().build();
}

B

public ResponseEntity<String> check(boolean input) {
    if (input) {
        return ResponseEntity.ok("Success");
    } else {
        return ResponseEntity.status(404).body("Not Found");
    }
}

C

public ResponseEntity<String> check(boolean input) {
    if (input) {
        return new ResponseEntity<>("Success", HttpStatus.OK);
    } else {
        return new ResponseEntity<>("Not Found", HttpStatus.NOT_FOUND);
    }
}

D

public ResponseEntity<String> check(boolean input) {
    if (input) {
        return ResponseEntity.ok("Success");
    }
    return ResponseEntity.notFound().body("Not Found");
}

💡 Hint

Check which options correctly set both status and body for 404 response.

Option B correctly returns 200 OK with body and 404 with body using fluent API. Option B is valid: ResponseEntity.notFound().build() returns 404 without body. Option B works but uses constructor style (requires HttpStatus import). Option B is invalid: notFound() has no body() method.