In a high-concurrency scenario using Java 21, which approach is recommended for I/O-bound operations?

The correct answer is A: Virtual Threads with structured concurrency. Virtual Threads (Project Loom) are ideal for I/O-bound operations as they have minimal overhead and can number in millions, improving scalability significantly.

An enterprise application requires different bean implementations based on runtime conditions. Which Spring feature is most suitable?

The correct answer is D: All of the above can be used depending on the scenario. @Conditional provides fine-grained control, @Profile handles environment-specific beans, and factory beans offer explicit creation logic. Choice depends on use case requirements.

Which pattern should be used to safely publish data from one thread to another?

The correct answer is B: Use synchronized, volatile, or thread-safe collections like ConcurrentHashMap. Safe publication requires using visibility mechanisms: synchronized (mutual exclusion), volatile (visibility), or thread-safe collections (both). Direct assignment without synchronization causes visibility issues in the memory model.

What is the correct order of JDBC operations?

The correct answer is A: Load Driver → Create Connection → Create Statement → Execute Query → Close Resources. The correct JDBC sequence is: 1) Load the JDBC driver, 2) Create connection, 3) Create statement, 4) Execute query, 5) Process results, 6) Close resources.

Which interface is used to execute precompiled SQL statements in JDBC?

The correct answer is B: PreparedStatement. PreparedStatement is used for precompiled SQL statements with parameters. It provides better performance and prevents SQL injection compared to Statement.

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Java Programming
Lambda Expressions

Java OOP, collections, multithreading

51 Q 10 Topics Take Mock Test

Difficulty: All Easy Medium Hard 51–51 of 51

Topics in Java Programming

All Basics & Syntax 100 OOP in Java 100 Collections Framework 100 Multithreading 100 Exception Handling 100 I/O Streams 100 JDBC 100 Generics 100 Lambda Expressions 100 Spring Framework Basics 58

Q.51 Medium Lambda Expressions

Which of the following lambda expressions is invalid?

A () -> System.out.println("Hello")

B x -> x * 2

C (int x, int y) -> { return x + y; }

D -> x + y

Correct Answer: D. -> x + y

EXPLANATION

Lambda must have parameter list (even if empty with ()). Missing parameter list '() -> x + y' is invalid syntax.

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Java Programming Lambda Expressions

Java Programming
Lambda Expressions