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.
What is the role of the @ControllerAdvice annotation in a Spring Boot application?
- To define request mapping for a controller.
- To handle exceptions at the controller level.
- To specify the HTTP request method.
- To declare a controller class.
The @ControllerAdvice annotation in a Spring Boot application is used to handle exceptions at the controller level. It allows you to define global exception handling logic that can be applied across multiple controllers. This is particularly useful for defining consistent error handling behavior in your application. The other options do not accurately describe the role of @ControllerAdvice.
In reactive programming with Spring Boot, which interface represents a stream of 0 or 1 item?
- Mono
- Flux
- Observable
- Stream
In Spring Boot's reactive programming, the Mono interface represents a stream of 0 or 1 item. It's part of Project Reactor, which is used for reactive programming in Spring. A Mono can emit either a single item or no item at all, making it suitable for situations where you expect zero or one result, such as fetching a single record from a database or handling optional values.
Which annotation is primarily used to declare a field to be validated using JSR-303 Bean Validation?
- @Assert
- @NotNull
- @Valid
- @Validate
The primary annotation used to declare a field to be validated using JSR-303 Bean Validation is @NotNull. This annotation specifies that a field must not be null, and it is commonly used to validate input parameters or form fields to ensure they have values. The other annotations mentioned have different purposes and are not typically used for field validation.
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.
What is the purpose of the @Valid annotation in Spring Boot when used in controller methods?
- It disables validation.
- It defines a new validation rule.
- It validates incoming request data.
- It initializes the Spring Boot application.
When the @Valid annotation is used in Spring Boot controller methods, it serves the purpose of validating incoming request data. This annotation is typically applied to method parameters, such as a @RequestBody, to trigger validation of the request body based on the validation rules defined for the associated class. It ensures that incoming data is valid according to the specified constraints. The other options are not the correct purposes of the @Valid annotation.
To optimize the garbage collection in JVM for a Spring Boot application, developers can configure the _____ option in JVM parameters.
- -XX:MaxGCPauseMillis
- -Xmx
- -Xms
- -XX:OnOutOfMemoryError
To optimize the garbage collection in the JVM for a Spring Boot application, developers can configure the -XX:MaxGCPauseMillis option in JVM parameters. This option allows developers to specify a target maximum pause time for garbage collection operations. By setting an appropriate value for this option, developers can fine-tune garbage collection behavior to minimize application pauses, ensuring smoother and more predictable application performance. Proper garbage collection configuration is essential for maintaining optimal application responsiveness and resource utilization.
You are developing an application with multiple authentication providers, including LDAP and a custom database. How would you configure Spring Security to authenticate users using multiple authentication providers?
- Using AuthenticationManagerBuilder with authenticationProvider()
- Creating separate login pages for each authentication provider
- Implementing custom login logic in each provider
- Using Spring Security's default AuthenticationProvider
To configure Spring Security to authenticate users using multiple providers, you would typically use AuthenticationManagerBuilder with authenticationProvider() to specify each authentication provider. This allows Spring Security to check against multiple providers for authentication. The other options are not standard practices for achieving this goal.
How can you configure a custom method security expression handler in Spring Security?
- By adding @MethodSecurityExpressionHandler annotation to a method.
- By extending the AbstractMethodSecurityExpressionHandler class.
- By implementing the MethodSecurityExpressionHandler interface and registering it in the Spring context.
- By modifying the application.properties file.
To configure a custom method security expression handler, you need to implement the MethodSecurityExpressionHandler interface, create a bean of it, and register it in the Spring context. This allows you to define custom security expressions for method-level security checks.
You need to implement a feature in a Spring Boot application where data is streamed from the server to the client as soon as it’s available. How would you implement this feature using reactive programming principles?
- Use WebSocket or Server-Sent Events (SSE) to push data to the client.
- Continuously poll the server for updates using AJAX requests.
- Use traditional REST endpoints to send periodic updates.
- Implement long polling to keep the connection open for updates.
To stream data from the server to the client as soon as it's available in a Spring Boot application using reactive programming principles, you should use WebSocket or Server-Sent Events (SSE). WebSocket and SSE allow for real-time data push to the client, unlike the other options, which involve more traditional request-response mechanisms or polling, which may not be as efficient for real-time updates.