Multithreading and Concurrency in Java

Test your understanding of threads,synchronization,and concurrency utilities.

1. Which interface should be implemented to create a thread in Java when extending Thread is not preferred?

Runnable Callable Executable Threadable

2. What does the 'synchronized' keyword in Java ensure for a method?

Atomicity only Visibility only Ordering only Atomicity, Visibility, and Ordering

3. Which method is used to make a thread wait for another thread to complete execution?

wait() join() sleep() yield()

4. What is the result type of the Runnable interface's run() method?

void Object Thread boolean

5. Which class represents the result of an asynchronous computation in Java?

Future Callable Promise Task

6. Which of the following is NOT a thread state in Java?

NEW RUNNING BLOCKED TERMINATED

7. What is the primary purpose of the volatile keyword in Java?

Ensure atomicity of compound operations Prevent instruction reordering and ensure visibility Create a daemon thread Synchronize method execution

8. What determines the default priority of a newly created thread in Java?

Always 5 The parent thread's priority The JVM's default (10) The system clock

9. Which methods throw InterruptedException when a thread is interrupted? (Select all that apply)

Thread.sleep(long) Object.wait() Thread.join() Thread.yield() Thread.start()

10. Which of the following are thread-safe collections? (Select all that apply)

ArrayList ConcurrentHashMap CopyOnWriteArrayList HashMap ConcurrentLinkedQueue

11. Which components are part of Java's Executor Framework? (Select all that apply)

ThreadPoolExecutor ScheduledExecutorService Executors Runnable Callable

12. Which conditions are necessary for a deadlock to occur? (Select all that apply)

Mutual Exclusion Hold and Wait No Preemption Circular Wait High CPU Usage

13. Which of the following are valid uses of the synchronized keyword? (Select all that apply)

Synchronized methods Synchronized static methods Synchronized blocks Synchronized variables Synchronized constructors

14. The volatile keyword guarantees atomicity for increment operations like i++.

True False

15. A thread in the BLOCKED state is waiting to acquire a monitor lock.

True False

16. ThreadLocal provides thread-safe access by sharing a single variable across threads.

True False

17. Calling Object.wait() releases the object's monitor lock.

True False

18. Name the interface that declares the call() method, which returns a value and may throw checked exceptions.

19. What method is used to wake all threads waiting on an object's monitor?

20. What is the common abbreviation for the Java concurrency utilities package (e.g., containing ConcurrentHashMap)?

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