Java Multithreading: 17 MCQs with answers

A lightweight sub-process that runs concurrently with other threads

A thread is a lightweight sub-process, the smallest unit of execution that runs concurrently within a process.

Implement the Runnable interface

Implementing the Runnable interface is one of the two ways to create a thread; the other is extending the Thread class.

start()

The start() method creates a new thread and calls the run() method inside that new thread.

To contain the code that executes when the thread is running

The run() method holds the task that the thread performs; it is invoked by the start() method.

It allows concurrent execution of tasks, improving resource utilization

Multithreading allows multiple tasks to run concurrently, which improves CPU utilization and responsiveness.

False

Calling start() more than once on the same thread throws IllegalThreadStateException.

5

The default priority of a thread is NORM_PRIORITY, which is 5.

yield()

yield() causes the current thread to pause, giving other threads of the same priority a chance to run.

To wait for a thread to finish before continuing

join() makes the calling thread wait until the specified thread completes its execution.

synchronized

The synchronized keyword ensures that only one thread can access a method or block at a time, preventing race conditions.

A situation where multiple threads access shared data concurrently, leading to inconsistent results

A race condition occurs when multiple threads access shared data without proper synchronization, causing unpredictable outcomes.

interrupt()

interrupt() sets the thread's interrupt status; the thread can then handle the interruption gracefully.

PAUSED

PAUSED is not a valid thread state; the valid states are NEW, RUNNABLE, BLOCKED, WAITING, TIMED_WAITING, and TERMINATED.

True

Synchronization ensures that only one thread accesses a critical section at a time, preventing race conditions.

BLOCKED

A thread enters the BLOCKED state when it tries to enter a synchronized block but the lock is held by another thread.

To make a variable thread-safe by ensuring visibility of changes across threads

volatile ensures that changes to a variable are immediately visible to other threads, preventing caching issues.

Two or more threads waiting indefinitely for each other's locks

Deadlock occurs when two or more threads are blocked forever, each waiting for a lock held by another.