Java Programming Questions & Answers

Q.41 Hard Spring Framework Basics

In Spring Framework 2024-25, which feature allows lazy initialization of beans?

A @Lazy annotation on @Bean or @Component

B @DeferredInit annotation

C Setting lazy-init='true' only in XML

D Spring automatically detects and lazily initializes all beans

Correct Answer: A. @Lazy annotation on @Bean or @Component

EXPLANATION

@Lazy annotation (available in modern Spring versions) marks beans for lazy initialization. It can be used on class level or with @Bean methods. XML also supports lazy-init attribute.

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Q.42 Hard Spring Framework Basics

What happens when a prototype-scoped bean has a dependency on a singleton-scoped bean in Spring?

A Compilation error occurs

B The singleton bean is correctly injected into each prototype instance

C The prototype bean becomes singleton

D A runtime exception is thrown

Correct Answer: B. The singleton bean is correctly injected into each prototype instance

EXPLANATION

A prototype bean can depend on singleton beans without issues. Each prototype instance gets the same singleton instance injected. The reverse (singleton depending on prototype) is problematic.

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Q.43 Hard Spring Framework Basics

An enterprise application needs different bean implementations based on environment (dev/prod). Which approach is most suitable?

A @Bean with conditional logic inside @Configuration

B @Conditional annotation with custom conditions

C @Profile annotation to define environment-specific beans

D Manual bean creation in main() method

Correct Answer: C. @Profile annotation to define environment-specific beans

EXPLANATION

@Profile allows defining beans for specific environments (dev, prod, test). Alternatively, @Conditional provides more granular control with custom conditions.

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Q.44 Medium Spring Framework Basics

Which Spring concept ensures that the same bean instance is reused throughout the application lifecycle?

A Prototype scope

B Request scope

C Singleton scope

D Session scope

Correct Answer: C. Singleton scope

EXPLANATION

Singleton scope (default) creates one bean instance per application context that is shared and reused across the entire application.

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Q.45 Medium Spring Framework Basics

A Spring Boot application starts with ClassPathXmlApplicationContext('application.xml'). What does this do?

A Creates an ApplicationContext and loads bean definitions from XML file on classpath

B Scans all @Component classes automatically

C Initializes Spring Security

D Creates embedded Tomcat server

Correct Answer: A. Creates an ApplicationContext and loads bean definitions from XML file on classpath

EXPLANATION

ClassPathXmlApplicationContext loads Spring bean definitions from an XML file located in the classpath, allowing traditional XML-based configuration.

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Q.46 Medium Spring Framework Basics

What is the difference between @Bean and @Component annotations?

A They are identical and interchangeable

B @Bean is on class level, @Component is on method level

C @Component is on class level, @Bean is on method level inside @Configuration classes

D @Bean only works with XML configuration

Correct Answer: C. @Component is on class level, @Bean is on method level inside @Configuration classes

EXPLANATION

@Component marks a class as a bean, while @Bean is used inside @Configuration classes to define beans through factory methods, providing more control.

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Q.47 Medium Spring Framework Basics

Consider a scenario where multiple beans of the same type exist. How can you specify which bean to inject?

A Use @Autowired alone

B Use @Qualifier annotation with bean name

C Use @Primary and @Qualifier together

D Delete all but one bean

Correct Answer: B. Use @Qualifier annotation with bean name

EXPLANATION

@Qualifier specifies the bean name to inject when multiple candidates exist. @Primary can also be used to mark a preferred bean.

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Q.48 Medium Spring Framework Basics

Which annotation is used to define configuration classes in Spring that replace XML configuration?

A @ConfigClass

B @SpringConfig

C @Configuration

D @Bean

Correct Answer: C. @Configuration

EXPLANATION

@Configuration marks a class as a source of bean definitions. It's equivalent to an XML <beans> element and works with @Bean methods.

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Q.49 Medium Spring Framework Basics

What is the role of ApplicationContext in Spring Framework?

A To execute SQL queries

B To manage beans, enable dependency injection, and provide application-wide features

C To compile Java code

D To generate REST endpoints automatically

Correct Answer: B. To manage beans, enable dependency injection, and provide application-wide features

EXPLANATION

ApplicationContext is the central Spring container that manages bean lifecycle, performs DI, and provides additional features like event publishing and message resolution.

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Q.50 Medium Spring Framework Basics

A developer needs to inject a bean only if it exists, otherwise skip injection. Which annotation should be used?

A @Required

B @Autowired(required=false)

C @Nullable

D @Optional

Correct Answer: B. @Autowired(required=false)

EXPLANATION

@Autowired(required=false) allows optional dependency injection. If the bean doesn't exist, no error is thrown.

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