ResponseEntity for full response control in Spring Boot - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What is the HTTP status code returned by this Spring Boot controller method?

Consider this Spring Boot controller method using ResponseEntity:

public ResponseEntity greet() {
    return ResponseEntity.status(201).body("Created greeting");
}

What HTTP status code will the client receive?

Spring Boot

public ResponseEntity<String> greet() {
    return ResponseEntity.status(201).body("Created greeting");
}

A 200 OK

B 201 Created

C 404 Not Found

D 500 Internal Server Error

💡 Hint

Look at the status method used in ResponseEntity.

The method explicitly sets the status to 201, which means 'Created'. So the client receives HTTP 201.

❓ state_output

intermediate

What is the response body content returned here?

Given this Spring Boot controller method:

public ResponseEntity getMessage() {
    return ResponseEntity.ok("Hello World");
}

What will be the exact content in the HTTP response body?

Spring Boot

public ResponseEntity<String> getMessage() {
    return ResponseEntity.ok("Hello World");
}

A Hello World

B "Hello World"

C null

D An empty string

💡 Hint

ResponseEntity.ok() sets the body to the string passed.

The body is the string "Hello World" without quotes in the actual HTTP response body.

📝 Syntax

advanced

Which option correctly creates a ResponseEntity with a custom header and status 202?

You want to return a ResponseEntity with status 202 Accepted and a custom header "X-Custom" with value "Value". Which code snippet is correct?

A return ResponseEntity.status(202).header("X-Custom", "Value").body("Accepted");

B return ResponseEntity.header("X-Custom", "Value").status(202).body("Accepted");

C return ResponseEntity.body("Accepted").status(202).header("X-Custom", "Value");

D return ResponseEntity.body("Accepted").header("X-Custom", "Value").status(202);

💡 Hint

Check the order of method calls on ResponseEntity builder.

ResponseEntity.status(int) returns a builder where you can add headers before calling body(). The order matters: status() then header() then body().

🔧 Debug

advanced

What is the result of this ResponseEntity usage?

Analyze this Spring Boot method:

public ResponseEntity errorExample() {
    return ResponseEntity.body("Missing status");
}

What happens when this code runs?

Spring Boot

public ResponseEntity<String> errorExample() {
    return ResponseEntity.body("Missing status");
}

A Compilation error: body() is not a static method

B Compilation error: missing import for ResponseEntity

C Runtime NullPointerException

D Returns HTTP 200 with body "Missing status"

💡 Hint

ResponseEntity.body(T) is a static factory method that returns 200 OK.

ResponseEntity.body(T body) is a static factory method that creates a ResponseEntity with HTTP 200 OK and the given body. No error occurs.

🧠 Conceptual

expert

Which ResponseEntity usage correctly returns a 204 No Content with no body?

You want to return a response with HTTP status 204 No Content and no response body. Which code snippet correctly does this?

A return ResponseEntity.status(204).body(null);

B return ResponseEntity.status(204).body("");

C return ResponseEntity.noContent().build();

D return ResponseEntity.ok().body(null);

💡 Hint

204 status means no body is allowed in the response.

ResponseEntity.noContent().build() returns a ResponseEntity with status 204 and no body, which is the correct way to send a No Content response.

Practice

1. What is the main purpose of using ResponseEntity in a Spring Boot REST controller?

easy

A. To control the HTTP status, headers, and body of the response

B. To automatically map JSON to Java objects

C. To handle database transactions

D. To configure application properties

Solution

1. Step 1: Understand ResponseEntity role

   ResponseEntity is designed to give full control over HTTP response details like status code, headers, and body.

2. Step 2: Compare with other options

   Mapping JSON, handling transactions, or configuring properties are unrelated to ResponseEntity's purpose.

3. Final Answer:

   To control the HTTP status, headers, and body of the response -> Option A

4. Quick Check:

   ResponseEntity controls full HTTP response [OK]

Hint: ResponseEntity controls status, headers, and body [OK]

Common Mistakes:

• Confusing ResponseEntity with JSON mapping
• Thinking it manages database operations
• Assuming it configures app settings

2. Which of the following is the correct way to create a ResponseEntity with status 404 and a body message "Not Found"?

easy

A. return ResponseEntity.create(404, "Not Found");

B. return ResponseEntity.body("Not Found").status(404);

C. return new ResponseEntity<>("Not Found", 404);

D. return ResponseEntity.status(404).body("Not Found");

Solution

1. Step 1: Check ResponseEntity builder methods

   The correct builder pattern is to call status() first, then body().

2. Step 2: Validate options

   return ResponseEntity.status(404).body("Not Found"); uses status(404).body("Not Found") correctly. return ResponseEntity.body("Not Found").status(404); reverses the order, which is invalid. return new ResponseEntity<>("Not Found", 404); uses a constructor but 404 should be HttpStatus, not int. return ResponseEntity.create(404, "Not Found"); uses a non-existent method.

3. Final Answer:

   return ResponseEntity.status(404).body("Not Found"); -> Option D

4. Quick Check:

   Use status().body() chaining [OK]

Hint: Call status() before body() to build ResponseEntity [OK]

Common Mistakes:

• Calling body() before status()
• Using integer instead of HttpStatus enum
• Using non-existent ResponseEntity methods

3. Given the code snippet:

return ResponseEntity.status(HttpStatus.CREATED)
    .header("Location", "/items/123")
    .body("Item created");

What will be the HTTP status and headers in the response?

medium

A. Status 201 Created with no headers

B. Status 201 Created with header Location: /items/123

C. Status 200 OK with header Location: /items/123

D. Status 404 Not Found with header Location: /items/123

Solution

1. Step 1: Analyze status method

   The code sets status to HttpStatus.CREATED which is 201.

2. Step 2: Analyze header method

   The header method adds a "Location" header with value "/items/123".

3. Final Answer:

   Status 201 Created with header Location: /items/123 -> Option B

4. Quick Check:

   Status = 201, Header Location set [OK]

Hint: status() sets code, header() adds headers [OK]

Common Mistakes:

• Assuming default 200 OK status
• Forgetting headers are added by header()
• Confusing status codes meanings

4. Identify the error in this Spring Boot controller method:

@GetMapping("/test")
public ResponseEntity<String> test() {
    return ResponseEntity.body("Hello").status(HttpStatus.OK);
}

medium

A. HttpStatus.OK is not a valid status

B. ResponseEntity.body() cannot be used without new keyword

C. The order of method calls is incorrect; status() must come before body()

D. The method must return String, not ResponseEntity

Solution

1. Step 1: Check method chaining order

   ResponseEntity builder requires calling status() before body(). Here, body() is called first, which is invalid.

2. Step 2: Validate other options

   ResponseEntity.body() is a static method returning a builder, no new keyword needed. HttpStatus.OK is valid. Returning ResponseEntity<String> is correct for REST.

3. Final Answer:

   The order of method calls is incorrect; status() must come before body() -> Option C

4. Quick Check:

   Call status() before body() [OK]

Hint: Always call status() before body() in ResponseEntity [OK]

Common Mistakes:

• Calling body() before status()
• Trying to instantiate ResponseEntity with new
• Confusing return types in controller

5. You want to return a JSON response with status 202 Accepted, a custom header "X-Request-ID" set to "abc123", and a body containing a Map with key "message" and value "Processing". Which code snippet correctly achieves this?

hard

A. return ResponseEntity.status(HttpStatus.ACCEPTED)
.header("X-Request-ID", "abc123")
.body(Map.of("message", "Processing"));

B. return ResponseEntity.body(Map.of("message", "Processing"))
.header("X-Request-ID", "abc123")
.status(HttpStatus.ACCEPTED);

C. return new ResponseEntity<>(Map.of("message", "Processing"), HttpStatus.ACCEPTED, Map.of("X-Request-ID", "abc123"));

D. return ResponseEntity.create(HttpStatus.ACCEPTED, Map.of("message", "Processing"))
.header("X-Request-ID", "abc123");

Solution

1. Step 1: Use correct builder pattern

   ResponseEntity builder requires calling status() first, then header(), then body().

2. Step 2: Validate options

   return ResponseEntity.status(HttpStatus.ACCEPTED) .header("X-Request-ID", "abc123") .body(Map.of("message", "Processing")); follows correct chaining and uses Map.of for body. return ResponseEntity.body(Map.of("message", "Processing")) .header("X-Request-ID", "abc123") .status(HttpStatus.ACCEPTED); calls body() first, invalid order. return new ResponseEntity<>(Map.of("message", "Processing"), HttpStatus.ACCEPTED, Map.of("X-Request-ID", "abc123")); uses a constructor with three arguments which does not exist. return ResponseEntity.create(HttpStatus.ACCEPTED, Map.of("message", "Processing")) .header("X-Request-ID", "abc123"); uses a non-existent create() method.

3. Final Answer:

   return ResponseEntity.status(HttpStatus.ACCEPTED) .header("X-Request-ID", "abc123") .body(Map.of("message", "Processing")); -> Option A

4. Quick Check:

   status() -> header() -> body() chaining [OK]

Hint: Chain status(), then header(), then body() for full control [OK]

Common Mistakes:

• Calling body() before status()
• Using non-existent ResponseEntity constructors
• Trying to use create() method which doesn't exist