What does the @ExceptionHandler annotation do in a Spring Boot application?
- Handles exceptions at the controller level.
- Defines a new exception class.
- Handles exceptions at the global level.
- Specifies a custom HTTP status code.
The @ExceptionHandler annotation in Spring Boot is used to handle exceptions at the global level. It allows you to define methods that can handle specific exceptions across multiple controllers. When an exception of the specified type occurs, the corresponding method is invoked to handle it. This is an essential part of effective exception handling in Spring Boot. The other options describe different functionalities or are incorrect.
Suppose you are working on a Spring Boot project and need to ensure that certain fields in the incoming request payload are consistent with each other (e.g., startDate should be before endDate). How would you implement this validation?
- Implement field consistency checks in a custom validator.
- Perform field consistency checks in the controller layer.
- Use exception handling to enforce field consistency.
- Use the @AssertTrue annotation for field consistency checks.
To enforce consistency between certain fields in the incoming request payload in a Spring Boot project, implementing field consistency checks in a custom validator is a suitable approach. The @AssertTrue annotation is typically used for boolean conditions, and exception handling is not the ideal way to validate such constraints. The controller layer should primarily handle request/response handling, not field-level validation.
In a Spring Boot application, the _____ annotation is used to bind the value of a method parameter to a named cookie value.
- @Cookie
- @CookieParam
- @CookieValue
- @ValueCookie
In a Spring Boot application, the @CookieValue annotation is used to bind the value of a method parameter to a named cookie value. This allows you to access and use cookies sent by the client in your controller methods. It simplifies the process of working with cookies in a Spring Boot application.
Which Java utility is primarily used for monitoring Java applications and troubleshoot performance issues?
- JVM Profiler
- Java Archive (JAR)
- Java Naming and Directory Interface (JNDI)
- JavaFX Scene Builder
The Java utility primarily used for monitoring Java applications and troubleshooting performance issues is a JVM Profiler. A JVM Profiler is a tool that allows you to gather detailed information about the runtime behavior of your Java application, including memory usage, CPU usage, method profiling, and more. Profilers like VisualVM, YourKit, and Java Mission Control (JMC) are popular choices for this purpose. JavaFX Scene Builder, Java Archive (JAR), and Java Naming and Directory Interface (JNDI) are not primarily used for monitoring and profiling Java applications.
How does the @Controller annotation interact with the view in a traditional Spring MVC application?
- It communicates with the view by forwarding control to a specific view template based on the request mapping.
- It directly renders the view by including the HTML/JSP content within the controller class.
- It generates view templates dynamically based on user interactions.
- It interacts with the view through AJAX requests only.
In a traditional Spring MVC application, the @Controller annotation is used to define a controller class that handles HTTP requests. It interacts with the view by forwarding control to a specific view template based on the request mapping defined in the controller method. The controller doesn't directly render HTML/JSP content or generate view templates dynamically; it simply controls the flow between the request and the view template. It can also handle AJAX requests if configured accordingly.
When creating a Custom Validator in Spring Boot, the isValid method must return _____ to indicate whether the value meets the constraint.
- FALSE
- TRUE
- a boolean value
- void
When creating a Custom Validator in Spring Boot, the isValid method must return void to indicate whether the value meets the constraint. The isValid method is used to perform the validation logic, and it should not return a boolean value directly. Instead, it should use the provided ConstraintValidatorContext to report validation errors.
What is the difference between @RestController and @Controller in Spring Boot?
- @Controller is used for MVC applications and returns HTML by default.
- @Controller is used for RESTful APIs and returns JSON by default.
- @RestController is used for MVC applications and returns HTML by default.
- @RestController is used for RESTful APIs and returns JSON by default.
The key difference is that @RestController is specifically designed for RESTful APIs and returns data in JSON format by default, while @Controller is used for traditional MVC applications and returns HTML by default. Mixing them up can lead to unexpected results, so choosing the right annotation is crucial for the desired functionality.
In Spring Boot, the _____ annotation can be used to define which beans should be registered in the context based on a conditional check.
- @ConditionalOnProperty
- @ConditionalOnClass
- @ConditionalOnBean
- @Conditional
The "@ConditionalOnProperty" annotation in Spring Boot allows you to define conditions under which a bean should be registered in the application context. It checks the specified property and registers the bean if the condition is met. The other options, such as "@ConditionalOnClass," "@ConditionalOnBean," and "@Conditional," serve different conditional registration purposes based on different conditions or criteria.
To bind the properties defined in the YAML file to a Java object, you can use the _____ annotation in Spring Boot.
- @Autowired
- @ConfigurationProperties
- @PropertySource
- @Value
To bind the properties defined in the YAML file to a Java object in Spring Boot, you can use the @ConfigurationProperties annotation. This annotation allows you to map YAML or properties file values to fields in a Java object, making it a powerful tool for handling configuration in Spring Boot applications.
How can database query optimization improve the performance of a Spring Boot application interacting with a database?
- By increasing the database server's RAM capacity.
- By minimizing the number of database queries and optimizing their execution.
- By offloading database queries to a separate server.
- By using in-memory databases for all data storage needs.
Database query optimization involves techniques such as indexing, query rewriting, and efficient database design. It aims to reduce the number of queries and improve their execution plans, resulting in faster response times and reduced resource consumption. In a Spring Boot application, well-optimized queries are crucial for efficient data retrieval and manipulation. Improperly optimized queries can lead to performance bottlenecks and increased response times.
The _____ utility in Spring Boot allows for creating disposable instances of common databases, web browsers, or anything that can run in a Docker container, for testing.
- @Disposable
- @DockerTest
- @Profile
- @TestContainers
Spring Boot, using the @TestContainers annotation, allows you to create disposable instances of databases, web browsers, or other services in Docker containers for testing purposes. It simplifies the process of setting up and tearing down these resources for testing.
To resolve ambiguity and specify which bean should be wired when there are multiple beans of the same type, one can use the _____ annotation in Spring
- @Component
- @Qualifier
- @Repository
- @Service
To resolve ambiguity when there are multiple beans of the same type, the "@Qualifier" annotation in Spring is used. It allows you to specify which bean should be wired by providing the name or ID of the desired bean. The other annotations, such as "@Component," "@Service," and "@Repository," are used for different purposes, like marking classes for component scanning, but they do not resolve bean wiring ambiguity.