@EnableCaching annotation in Spring Boot - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What happens when @EnableCaching is added to a Spring Boot application?

Consider a Spring Boot application with a service method annotated with @Cacheable. What is the effect of adding @EnableCaching to the main configuration class?

Spring Boot

import org.springframework.cache.annotation.EnableCaching;
import org.springframework.context.annotation.Configuration;

@Configuration
@EnableCaching
public class AppConfig {
}

A It automatically creates a cache store but does not enable caching on any methods.

B It disables all caching in the application, forcing methods to always execute fully.

C It activates Spring's annotation-driven cache management, enabling caching behavior on methods annotated with @Cacheable.

D It only enables caching for methods annotated with @CachePut, ignoring @Cacheable annotations.

💡 Hint

Think about what @EnableCaching does in relation to @Cacheable methods.

The @EnableCaching annotation tells Spring to look for caching annotations like @Cacheable and activate caching behavior on those methods. Without it, caching annotations are ignored.

📝 Syntax

intermediate

Identify the correct way to enable caching in a Spring Boot application

Which of the following code snippets correctly enables caching in a Spring Boot application?

A

@Configuration
@EnableCaching
public class CacheConfig {}

B

@EnableCaching
public class CacheConfig {}

C

@Configuration
@EnableCache
public class CacheConfig {}

D

@Configuration
@EnableCaching(true)
public class CacheConfig {}

💡 Hint

Remember the exact annotation name and required annotations for configuration classes.

The @EnableCaching annotation must be used on a class annotated with @Configuration to enable caching properly. @EnableCache does not exist and @EnableCaching does not take parameters.

🔧 Debug

advanced

Why does caching not work despite @EnableCaching being present?

Given the following code, why might caching not be working as expected? @Configuration @EnableCaching public class AppConfig {} @Service public class MyService { @Cacheable("items") public String getItem(String id) { return "Item" + id; } } Assume the application runs but caching does not reduce method calls.

A The @EnableCaching annotation must be placed on the service class, not the configuration class.

B The cache name "items" is invalid and must be registered explicitly in the cache manager.

C The @Cacheable annotation requires a key attribute to work properly.

D The service method is called from within the same class, so Spring's proxy does not intercept the call to apply caching.

💡 Hint

Think about how Spring proxies work and when caching applies.

Spring caching works through proxies. If a method annotated with @Cacheable is called from within the same class, the proxy is bypassed and caching does not occur.

🧠 Conceptual

advanced

What is the role of @EnableCaching in Spring's caching abstraction?

Which statement best describes the role of @EnableCaching in a Spring application?

A @EnableCaching disables caching unless a custom cache manager bean is provided.

B @EnableCaching activates the processing of caching annotations and configures a cache manager if none is defined.

C @EnableCaching replaces the need to annotate methods with @Cacheable or other caching annotations.

D @EnableCaching automatically creates and manages all caches without any further configuration.

💡 Hint

Consider what enabling caching means for annotation processing and cache manager setup.

@EnableCaching enables Spring to detect caching annotations and sets up a default cache manager if none is provided. It does not create caches automatically nor replace caching annotations.

❓ state_output

expert

What is the output count of method calls with @EnableCaching and @Cacheable?

Given this Spring Boot service: @Service public class CounterService { private int count = 0; @Cacheable("numbers") public int getNumber(int input) { count++; return input * 2; } public int getCount() { return count; } } And this test code: CounterService service = context.getBean(CounterService.class); service.getNumber(5); service.getNumber(5); service.getNumber(10); service.getNumber(5); int calls = service.getCount(); What is the value of calls after these calls if @EnableCaching is present?

A 2

B 1

C 4

D 3

💡 Hint

Remember that @Cacheable caches results by method parameters.

The method is called with inputs 5, 5, 10, 5. The first call with 5 executes and increments count. The second call with 5 returns cached result, no increment. The call with 10 executes and increments count. The last call with 5 returns cached result again. So count increments twice.