Conditional bean creation in Spring Boot - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is @Conditional annotation used for in Spring Boot?

It is used to create beans only when certain conditions are met, like checking if a class exists or a property is set.

beginner

Name two common built-in conditions for conditional bean creation in Spring Boot.

@ConditionalOnProperty and @ConditionalOnClass are commonly used to create beans based on property values or presence of classes.

intermediate

How does @ConditionalOnProperty control bean creation?

It creates a bean only if a specific property is present and optionally matches a value in the application configuration.

beginner

What happens if a condition in @Conditional is not met?

The bean is not created or registered in the Spring context, so it won't be available for injection.

intermediate

Explain how @ConditionalOnMissingBean helps in bean creation.

It creates a bean only if no other bean of the same type or name is already defined, helping avoid duplicates.

Which annotation creates a bean only if a certain property is set in Spring Boot?

A @Autowired

B @ConditionalOnClass

C @ConditionalOnMissingBean

D @ConditionalOnProperty

@ConditionalOnProperty checks for a property value before creating the bean.

What does @ConditionalOnClass check before creating a bean?

A If a property is set

B If a class is present on the classpath

C If a bean is missing

D If a method is called

@ConditionalOnClass creates a bean only if a specific class exists in the project.

If a condition in @Conditional is false, what happens?

A Bean is not created

B Bean is created anyway

C Application crashes

D Bean is created with default values

The bean is skipped and not registered in the Spring context.

Which annotation prevents bean creation if another bean of the same type exists?

A @ConditionalOnMissingBean

B @ConditionalOnProperty

C @ConditionalOnClass

D @Component

@ConditionalOnMissingBean ensures no duplicate beans of the same type are created.

Why use conditional bean creation in Spring Boot?

A To avoid using annotations

B To always create all beans

C To create beans only when needed

D To slow down application startup

Conditional creation helps optimize resources by creating beans only under certain conditions.

Describe how you can use conditional annotations to control bean creation in Spring Boot.

Think about checking properties or classes before creating beans.

Explain the difference between @ConditionalOnProperty and @ConditionalOnMissingBean.

One looks at config, the other at existing beans.