Java and Spring Boot

Exam for Java and Spring Boot

1. Project Loom and Virtual Threads, how does the JVM handle a virtual thread that performs a blocking I/O operation ?

• A. The JVM creates a new platform thread specifically to handle the blocked state
• B. Virtual threads cannot perform blocking I/O; they must use non-blocking NIO APIs
• C. The underlying platform thread is blocked until the I/O operation completes
• D. The virtual thread is unmounted from the platform thread, allowing the platform thread to execute other virtual threads

2. When designing a database for a 'Read-Heavy' system, which strategy is most effective for improving performance ?

• A. Normalizing the database to the 3rd Normal Form (3NF)
• B. Removing all indexes to speed up table scans
• C. Strictly using 'Write-Through' caching only
• D. Implementing Denormalization and Materialized Views

3. In Spring Transaction management, which Isolation level prevents 'Phantom Reads' ?

• A. SERIALIZABLE
• B. REPEATABLE_READ
• C. READ_UNCOMMITTED
• D. READ_COMMITTED

4. What is the primary benefit of using GraalVM Native Image for a Spring Boot application ?

• A. Significantly faster startup time and lower memory footprint
• B. Improved peak throughput after the JIT compiler warms up
• C. Ability to use Dynamic Class Loading at runtime
• D. Automatic conversion of synchronous code to asynchronous code

5. Which Resilience4j pattern is used to prevent a cascade of failures by temporarily stopping requests to a struggling downstream service ?

• A. Retry
• B. Bulkhead
• C. Rate Limiter
• D. Circuit Breaker

6. How does Spring WebFlux handle concurrency compared to Spring MVC (Tomcat) ?

• A. It uses one thread per request
• B. It automatically converts all Java Collections to Streams
• C. It uses an event-loop model with a small, fixed number of threads to handle many concurrent connections
• D. It requires a Virtual Thread for every incoming socket connection

7. In a Spring Boot application, how do you handle multiple DataSources properly ?

• A. Put all database credentials in a single application.properties string separated by commas
• B. Configure separate @Bean definitions for each DataSource and use @Qualifier to inject them
• C. Define multiple @Primary beans for each DataSource
• D. Multiple DataSources are not supported in Spring Boot

8. When processing a file that is significantly larger than the available RAM, which approach is recommended ?

• A. Increase the JVM heap size to be larger than the file.
• B. Read the entire file into a List.
• C. Convert the file to a Base64 string before processing.
• D. Use Files.lines() or a BufferedReader to process the file line-by-line using a Stream

9. How does Java's 'CompletableFuture' differ from a standard 'Future' ?

• A. Standard Future is faster than CompletableFuture
• B. CompletableFuture allows for functional-style callbacks and chaining (e.g., thenApply, thenAccept)
• C. CompletableFuture cannot be canceled.
• D. CompletableFuture only works with Virtual Threads

10. Which of the following is a key feature introduced in the Java Stream API for better efficiency ?

• A. Replacing all loops with recursive functions.
• B. Lazy evaluation and Short-circuiting
• C. Eager evaluation of all intermediate operations.
• D. Automatic conversion of data to JSON