Question 1

Which method(s) are part of the Thread class?
i.public void run(Runnable runnable)
II.public void start(Runnable runnable)
III.public void start()

Accepted Answer

A) Only I 
B) Only II 
C) Only III 
D) II and III

Question 2

Each thread runs for a short amount of time, called a ____________________.

Accepted Answer

A) thread allotment 
B) thread time slot 
C) time slice 
D) run time slice

Question 3

Under what conditions are locks unnecessary for multi-threaded programs?

Accepted Answer

A) When the threads are all of the same class. 
B) When the threads are different classes. 
C) When the threads do not share data. 
D) When the shared data only has a single method.

Question 4

Examine the SharedData class shown below.Suppose two threads are created so that each has access to the same SharedData object.Thread one calls setSharedData eight times with values 1...8 respectively, sleeping for 30 milliseconds between calls.Thread two calls getSharedData eight times, also sleeping for 30 milliseconds between calls.Suppose thread two receives values 1, 2, 3, 4, 5, 6, 7, 8 respectively on its calls.Should we expect the same values for each program run?

Accepted Answer

A) Yes, because the sleep times are equal in between calls. 
B) Yes, because that's the same order used by thread one to set the values. 
C) No, because thread one may not set the data as 1,2,3,4,5,6,7,8 respectively. 
D) No, because a race condition may result in a

Question 5

Suppose that the class XYZ implements the interface Runnable.Which code creates a thread object and makes it available to the scheduler to be executed?

Accepted Answer

A)   
B)   
C)   
D)

Question 6

The ____________ occurs when a thread that is not running is interrupted.

Accepted Answer

A) InterruptException 
B) InterruptedException 
C) ThreadException 
D) ThreadTerminatedException

Question 7

What is the relationship between synchronized code and code that is locked using a ReentrantLock object?

Accepted Answer

A) synchronized code stops the race condition, locks do not. 
B) synchronized is a single lock, but we may have many ReentrantLock objects. 
C) The two are exactly the same. 
D) The two concepts are not related.

Question 8

In the initial release of the Java library, the Thread class had a stop method to terminate a thread.However, that method is now _______________

Accepted Answer

A) forbidden 
B) not recommended 
C) unwise 
D) deprecated

Question 9

The ________ method is called by a thread that has just changed the state of some shared data in a way that may benefit waiting threads.

Accepted Answer

A) run 
B) lock 
C) unlock 
D) signalAll

Question 10

The ___________ method does not actually cause threads to terminate; it merely sets a Boolean field in the thread data structure.

Accepted Answer

A) stop 
B) await 
C) sleep 
D) interrupt

Question 11

Consider an old fashioned telephone booth that can be occupied by one person at a time.Suppose one person went in and dialed a part of her number, and had to leave the booth.A second person went in and dialed a part of his number, and before the number was fully dialed, a connection to some other phone was made.What Java threads analogy would prevent this undesirable scenario?
i.Acquire the lock prior to entering the booth
II.Dial a complete number when inside the booth
III.Hang up the phone and release the lock upon exiting the booth

Accepted Answer

A) Only I 
B) I and II 
C) I and III 
D) I, II, and III

Question 12

Which of the following is a characteristic of threads?

Accepted Answer

A) The order of the execution of parallel threads is somewhat random 
B) When running multiple parallel threads, the threads are exactly interleaved 
C) The thread scheduler executes the threads in the same order as its call 
D) Parallel threads run exactly at the same time and in the same order

Question 13

Which of the following statements is correct?

Accepted Answer

A) If a thread sleeps after acquiring a lock, it blocks all other threads that want to use the same lock. 
B) When a thread calls await, it is simply deactivated in the same way as a thread that reaches the end of its time slice. 
C) A thread pool is designed to encapsulate the concept of a sequence of statements that can run in parallel with other tasks, without equating it with the concept of a thread, a potentially expensive resource that is managed by the operating system. 
D) Under no circumstances should you terminate a running thread.

Question 14

A GUI should be responsive to the user.If a GUI interaction starts a time-consuming task, the GUI may not be responsive to the user until the task completes.Which approach would make the GUI responsive under these circumstances?

Accepted Answer

A) As you run the task, break and check for events. 
B) Ask the user if she is sure she wants to run the task. 
C) Run the task in a separate thread. 
D) Disable the GUI during the task.

Question 15

Assume three threads share a BankAccount object with a balance initially zero (0), a ReentrantLock named myLock, and a condition object on myLock named insufficientFunds, as shown below.Thread one calls withdraw(30), then thread two calls withdraw(20) and thread three calls deposit(45).What is the balance after the three calls?

Accepted Answer

A) 0 
B) 15 or 25 
C) 45 
D) -5

Question 16

Which of the following class declarations could run in a thread?
i.public interface MyRunnable extends Runnable { ...}
II.public class MyRunnable extends Runnable { ...}
III.public class MyRunnable implements Runnable { ...}

Accepted Answer

A) Only II 
B) Only III 
C) I and II 
D) II and III

Question 17

Examine the SharedData class shown below.Suppose two threads are created so that each has access to the same SharedData object.Thread one calls setSharedData ten times with values 1...10 respectively, sleeping for a random number of milliseconds between calls.Thread two calls getSharedData eight times, also sleeping for a random number of milliseconds between calls.Which of the following could be the last two values received by thread two?

Accepted Answer

A) 8, 10 
B) 10, 9 
C) 10, 8 
D) 8, 7

Question 18

Given a two-CPU machine and four threads, how many of the threads can execute in parallel?

Accepted Answer

A) Only 1 can execute at a time. 
B) 2 can execute in parallel. 
C) 3 can execute in parallel. 
D) All 4 can execute in parallel.

Question 19

What is likely to be true when thread one is downloading a 1MB file while thread two is downloading another 1MB file?

Accepted Answer

A) The files download twice as fast as they would if one thread downloaded both files. 
B) The files download half as fast as they would if one thread downloaded both files. 
C) When thread one is half done, thread two is about half done. 
D) The faster thread will interrupt the other thread.

Question 20

When is it a good idea to call notifyAll in a synchronized method?

Accepted Answer

A) Whenever you exit it. 
B) Upon exit, but only if threads before have called wait. 
C) Upon exit, but only if the thread has replenished a needed resource. 
D) Immediately upon entering the method.

Exam 22: Multithreading

Which method(s) are part of the Thread class? i.public void run(Runnable runnable) II.public void start(Runnable runnable) III.public void start()