@Profile for environment-specific beans in Spring Boot - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to activate a bean only for the 'dev' environment.

Spring Boot

@Profile("[1]")
@Component
public class DevService {}

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

Adefault

Bprod

Cdev

Dtest

Attempts:

3 left

💡 Hint

Common Mistakes

Using a profile name that does not match any active environment.

Forgetting to annotate the class with @Component.

The @Profile annotation activates the bean only when the specified profile is active. Here, 'dev' activates the bean for the development environment.

2fill in blank

medium

Complete the code to define a bean active only when the 'prod' profile is set.

Spring Boot

@Profile("[1]")
@Bean
public DataSource dataSource() {
    return new DataSource();
}

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

Alocal

Bprod

Ctest

Ddev

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'dev' or 'test' instead of 'prod' for production beans.

Not annotating the method with @Bean.

The @Profile annotation with 'prod' ensures this bean is created only in the production environment.

3fill in blank

hard

Fix the error in the annotation to activate the bean only for the 'test' profile.

Spring Boot

@Profile([1])
@Component
public class TestService {}

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

A"test"

Btest

C'test'

D["test"]

Attempts:

3 left

💡 Hint

Common Mistakes

Omitting quotes around the profile name.

Using single quotes instead of double quotes.

The @Profile annotation requires a string literal with double quotes around the profile name.

4fill in blank

hard

Fill both blanks to create a bean active for either 'dev' or 'test' profiles.

Spring Boot

@Profile([1])
@Component
public class MultiEnvService {}

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

A{"dev", "test"}

B"dev"

C"dev" | "test"

D"dev", "prod"

Attempts:

3 left

💡 Hint

Common Mistakes

Using bitwise OR operator '|' instead of comma.

Not enclosing profiles in quotes.

The @Profile annotation accepts multiple profiles as a comma-separated list of string literals to activate the bean for any of those profiles.

5fill in blank

hard

Fill all three blanks to define a bean active only when the 'prod' profile is active and annotate it as a component.

Spring Boot

[1]
@Profile([2])
public class [3] {}

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

A@Component

B"prod"

CProdService

D@Service

Attempts:

3 left

💡 Hint

Common Mistakes

Using @Service instead of @Component if the question expects @Component.

Omitting quotes around the profile name.

Using a class name that does not match the profile.

The class must be annotated with @Component to be a Spring bean, @Profile("prod") to activate it only in production, and named appropriately.

Practice

1. What is the main purpose of the @Profile annotation in Spring Boot?

easy

A. To define the database connection URL

B. To schedule tasks at fixed intervals

C. To create beans only for specific environments

D. To handle HTTP requests in controllers

Solution

1. Step 1: Understand the role of @Profile

   The @Profile annotation is used to mark beans that should only be created when a specific environment profile is active.

2. Step 2: Compare with other options

   Options A, C, and D relate to other Spring Boot features but not to environment-specific bean creation.

3. Final Answer:

   To create beans only for specific environments -> Option C

4. Quick Check:

   @Profile controls bean creation per environment [OK]

Hint: Remember: @Profile controls which beans load per environment [OK]

Common Mistakes:

• Confusing @Profile with @Component or @Service
• Thinking @Profile sets database URLs
• Assuming @Profile schedules tasks

2. Which of the following is the correct way to use @Profile on a Spring bean class for the "dev" environment?

easy

A. @Profile("dev")
public class DevService {}

B. @Profile(dev)
public class DevService {}

C. @Profile({dev})
public class DevService {}

D. @Profile(["dev"])
public class DevService {}

Solution

1. Step 1: Check correct syntax for @Profile

   The @Profile annotation requires a string value in quotes, e.g., @Profile("dev").

2. Step 2: Analyze each option

   @Profile(["dev"]) public class DevService {} uses square brackets, invalid Java annotation syntax. @Profile(dev) public class DevService {} misses quotes around "dev", syntax error. @Profile({dev}) public class DevService {} uses braces but misses quotes around "dev", syntax error. @Profile("dev") public class DevService {} uses correct quoted string syntax.

3. Final Answer:

   @Profile("dev") public class DevService {} -> Option A

4. Quick Check:

   @Profile needs quoted string [OK]

Hint: Use quotes around profile names in @Profile [OK]

Common Mistakes:

• Omitting quotes around profile names
• Using square brackets instead of curly braces
• Confusing array syntax with string

3. Given the following Spring Boot configuration and beans, what will be the output when the active profile is set to "prod"?

@Profile("dev")
@Component
public class DevBean {
    public String getMessage() { return "Development Bean"; }
}

@Profile("prod")
@Component
public class ProdBean {
    public String getMessage() { return "Production Bean"; }
}

@Component
public class BeanUser {
    private final Object bean;
    public BeanUser(@Autowired(required = false) Object bean) { this.bean = bean; }
    public String show() { return bean == null ? "No Bean" : ((ProdBean)bean).getMessage(); }
}

medium

A. Development Bean

B. Production Bean

C. ClassCastException at runtime

D. No Bean

Solution

1. Step 1: Identify active profile and beans created

   With profile "prod" active, only ProdBean is created. DevBean is not created.

2. Step 2: Analyze BeanUser constructor injection

   BeanUser tries to autowire an Object bean with @Autowired(required = false). Spring injects the available ProdBean instance as it matches.

3. Step 3: Check the show() method

   In show(), bean is cast to ProdBean, which succeeds, returning "Production Bean".

4. Final Answer:

   Production Bean -> Option B

5. Quick Check:

   Prod profile loads ProdBean successfully [OK]

Hint: Profile determines available beans for injection [OK]

Common Mistakes:

• Thinking Object type causes injection failure
• Expecting ClassCastException with matching profile
• Confusing which beans load per profile

4. You have two beans annotated with @Profile("test") and @Profile("prod") respectively. When running the app with no active profile set, you get a NoSuchBeanDefinitionException. What is the most likely cause?

medium

A. The beans are not annotated with @Component

B. The beans have syntax errors in @Profile annotation

C. Spring Boot does not support @Profile annotation

D. No profile is active, so no beans with @Profile are created

Solution

1. Step 1: Understand @Profile behavior with no active profile

   If no profile is active, Spring does not create beans annotated with any specific profile.

2. Step 2: Analyze exception cause

   NoSuchBeanDefinitionException means Spring could not find a bean to inject because none were created due to missing active profile.

3. Final Answer:

   No profile is active, so no beans with @Profile are created -> Option D

4. Quick Check:

   No active profile means no profile-specific beans [OK]

Hint: Beans with @Profile need active profile to load [OK]

Common Mistakes:

• Assuming beans load without active profile
• Blaming syntax errors without checking profiles
• Ignoring need for @Component on beans

5. You want to create a bean that is active in both "dev" and "test" profiles but not in "prod". Which @Profile annotation usage correctly achieves this?

hard

A. @Profile({"dev", "test"})

B. @Profile("dev & test")

C. @Profile("dev | test")

D. @Profile({"dev & test"})

Solution

1. Step 1: Understand @Profile multiple values usage

   Using @Profile({"dev", "test"}) means the bean is active if either "dev" OR "test" profile is active.

2. Step 2: Analyze other options

   @Profile("dev & test") and D use string with "&" which is invalid syntax for multiple profiles. @Profile("dev | test") uses "|" inside string which is not supported syntax.

3. Final Answer:

   @Profile({"dev", "test"}) -> Option A

4. Quick Check:

   Use array of profiles for OR condition in @Profile [OK]

Hint: Use array syntax for multiple profiles in @Profile [OK]

Common Mistakes:

• Using string with & or | inside @Profile
• Confusing AND and OR logic in profiles
• Forgetting to use curly braces for multiple profiles