@EnableCaching annotation in Spring Boot - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to enable caching in a Spring Boot application.

Spring Boot

@Configuration
@[1]
public class CacheConfig {
    @Bean
    public CacheManager cacheManager() {
        return new ConcurrentMapCacheManager("items");
    }
}

Drag options to blanks, or click blank then click option'

AEnableTransactionManagement

BEnableScheduling

CEnableAsync

DEnableCaching

Attempts:

3 left

💡 Hint

Common Mistakes

Using @EnableScheduling instead of @EnableCaching

Forgetting to add @EnableCaching on a configuration class

The @EnableCaching annotation activates Spring's annotation-driven cache management capability.

2fill in blank

medium

Complete the method annotation to cache the result of the method.

Spring Boot

public class ProductService {
    @[1]("products")
    public Product getProductById(Long id) {
        // method implementation
    }
}

Drag options to blanks, or click blank then click option'

ACacheable

BCachePut

CCacheEvict

DCacheConfig

Attempts:

3 left

💡 Hint

Common Mistakes

Using @CachePut when @Cacheable is needed

Not specifying the cache name in the annotation

The @Cacheable annotation tells Spring to cache the result of the method using the specified cache name.

3fill in blank

hard

Fix the error in the cache eviction annotation to clear the cache named 'users'.

Spring Boot

public class UserService {
    @CacheEvict(cacheNames = [1])
    public void clearUserCache() {
        // method implementation
    }
}

Drag options to blanks, or click blank then click option'

A"user"

Busers

C"users"

Duser

Attempts:

3 left

💡 Hint

Common Mistakes

Not using quotes around the cache name

Using singular instead of plural cache name

The cacheNames attribute requires the cache name as a string literal, so it must be quoted.

4fill in blank

hard

Fill both blanks to create a cache manager bean that uses a simple concurrent map cache.

Spring Boot

@Bean
public CacheManager cacheManager() {
    return new [1]([2]);
}

Drag options to blanks, or click blank then click option'

AConcurrentMapCacheManager

B"defaultCache"

C"itemsCache"

DSimpleCacheManager

Attempts:

3 left

💡 Hint

Common Mistakes

Using SimpleCacheManager without configuring caches

Passing cache name without quotes

ConcurrentMapCacheManager is a simple cache manager using concurrent maps. The cache name must be a string.

5fill in blank

hard

Fill all three blanks to define a cacheable method that caches by product ID and evicts cache on update.

Spring Boot

public class ProductService {

    @Cacheable(cacheNames = [1], key = "#[2]")
    public Product getProduct(Long [2]) {
        // fetch product
    }

    @CacheEvict(cacheNames = [1], key = "#[2]")
    public void updateProduct(Long [2]) {
        // update product
    }
}

Drag options to blanks, or click blank then click option'

A"products"

Bid

C"productId"

D"items"

Attempts:

3 left

💡 Hint

Common Mistakes

Using different cache names for caching and eviction

Mismatching key parameter names

The cache name is 'products'. The key uses the method parameter named 'id' to cache and evict the correct entry.

Practice

1. What is the main purpose of the @EnableCaching annotation in a Spring Boot application?

easy

A. To activate caching support so methods annotated with @Cacheable can cache results

B. To disable all caching mechanisms in the application

C. To configure database connections automatically

D. To enable security features for REST endpoints

Solution

1. Step 1: Understand @EnableCaching role

   This annotation activates Spring's caching support, allowing caching annotations to work.

2. Step 2: Connect with @Cacheable

   Methods annotated with @Cacheable store their results in cache only if caching is enabled.

3. Final Answer:

   To activate caching support so methods annotated with @Cacheable can cache results -> Option A

4. Quick Check:

   @EnableCaching enables caching [OK]

Hint: Remember: @EnableCaching turns caching ON [OK]

Common Mistakes:

• Thinking @EnableCaching disables caching
• Confusing it with database or security annotations
• Assuming it caches data by itself without @Cacheable

2. Which of the following is the correct way to enable caching in a Spring Boot application?

easy

A. @CacheEnable

B. @EnableCache

C. @EnableCaching

D. @CachingEnable

Solution

1. Step 1: Recall the exact annotation name

   The correct annotation to enable caching is @EnableCaching.

2. Step 2: Check other options for typos

   Options B, C, and D are incorrect because they are not valid Spring annotations.

3. Final Answer:

   @EnableCaching -> Option C

4. Quick Check:

   Correct annotation spelling is @EnableCaching [OK]

Hint: Look for exact spelling: EnableCaching, not EnableCache [OK]

Common Mistakes:

• Using incorrect annotation names with similar words
• Missing the capital 'C' in Caching
• Confusing with other Spring annotations

3. Given the following Spring Boot code snippet, what will be the output when getData() is called twice?

@EnableCaching
@Service
public class DataService {
  private int count = 0;

  @Cacheable("dataCache")
  public String getData() {
    count++;
    return "Call number: " + count;
  }
}

medium

A. ["Call number: 1", "Call number: 1"]

B. ["Call number: 2", "Call number: 2"]

C. ["Call number: 0", "Call number: 1"]

D. ["Call number: 1", "Call number: 2"]

Solution

1. Step 1: Understand caching effect on method calls

   The first call to getData() runs the method, increments count to 1, and caches the result.

2. Step 2: Analyze second call behavior

   The second call returns the cached result without running the method again, so count stays 1.

3. Final Answer:

   ["Call number: 1", "Call number: 1"] -> Option A

4. Quick Check:

   Cache returns same result on repeated calls [OK]

Hint: Cached method runs once; repeated calls return cached result [OK]

Common Mistakes:

• Assuming count increments on every call despite caching
• Ignoring that @Cacheable caches method output
• Confusing cache key usage

4. Identify the error in the following Spring Boot configuration that prevents caching from working:

@Configuration
public class CacheConfig {
  @Bean
  public CacheManager cacheManager() {
    return new ConcurrentMapCacheManager("items");
  }
}

medium

A. Cache name "items" is invalid

B. Missing @EnableCaching annotation on configuration class

C. CacheManager bean should return null

D. CacheManager must be annotated with @Service

Solution

1. Step 1: Check caching activation

   Defining a CacheManager bean is not enough; caching must be enabled with @EnableCaching.

2. Step 2: Verify other options

   CacheManager returning null or invalid cache names are incorrect; @Service is unrelated here.

3. Final Answer:

   Missing @EnableCaching annotation on configuration class -> Option B

4. Quick Check:

   Enable caching with @EnableCaching [OK]

Hint: Always add @EnableCaching to activate caching [OK]

Common Mistakes:

• Forgetting to add @EnableCaching annotation
• Misunderstanding CacheManager bean role
• Wrong annotation usage on CacheManager

5. You want to cache results of a method that takes a user ID and returns user details. You also want to clear the cache when user data updates. Which combination of annotations and configuration correctly achieves this in Spring Boot?

hard

A. Use @EnableCaching on service class, @CachePut("users") on get method, and no annotation on update method

B. Use @CacheEvict on config class, @EnableCaching on update method, and no caching on get method

C. Use @Cacheable("users") on config class, @EnableCaching on get method, and @CacheEvict on update method

D. Use @EnableCaching on config class, @Cacheable("users") on get method, and @CacheEvict(value = "users", key = "#userId") on update method

Solution

1. Step 1: Enable caching globally

   Add @EnableCaching on a configuration or main class to activate caching support.

2. Step 2: Cache method results and evict on update

   Use @Cacheable("users") on the method fetching user details to cache results. Use @CacheEvict(value = "users", key = "#userId") on the update method to clear cache for that user.

3. Final Answer:

   Use @EnableCaching on config class, @Cacheable("users") on get method, and @CacheEvict(value = "users", key = "#userId") on update method -> Option D

4. Quick Check:

   Enable caching + cache get + evict on update [OK]

Hint: Enable caching, cache gets, evict on updates [OK]

Common Mistakes:

• Not enabling caching globally with @EnableCaching
• Using @CachePut instead of @CacheEvict for clearing cache
• Placing annotations on wrong classes or methods