Which interface in java.io package must a Java class implement to enable object serialization into a byte stream?
Option B is correct. java.io.Serializable is a marker interface (with no methods) that signals to the JVM that objects of the implementing class can be serialized.
In Java concurrency, what interface in java.util.concurrent package represents a task that returns a result and may throw a checked exception?
Option A is correct. Callable<V> is a functional interface whose call() method returns a result of type V and can throw checked exceptions, unlike Runnable's run() method.
Which interface in java.util.concurrent provides a high-level framework for managing and executing asynchronous tasks using worker thread pools?
Option A is correct. ExecutorService manages thread creation, lifecycle, and task execution pools (e.g., via Executors.newFixedThreadPool()), decoupling task submission from execution details.
What object in java.util.concurrent represents the pending result of an asynchronous computation submitted to an ExecutorService?
Option B is correct. A Future<V> represents the result of an asynchronous computation. Methods like get() block until computation completes to retrieve the result.
Which concurrency utility in Java allows one or more threads to wait until a set of operations performed in other threads completes before proceeding?
Option A is correct. CountDownLatch is initialized with a given count. Threads call await() to wait until other threads decrement the count to zero via countDown().