Question 1

The thread that calls signalAll must own the lock that belongs to the condition object on which signalAll is called. Otherwise, a(n) _______ ________ is thrown.

Accepted Answer

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

Question 2

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. B

Question 3

The _____________ interface 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.

Accepted Answer

A)   Thread
B)   Runnable
C)   MyRunnable
D)   Threadable B

Question 4

Which exception must be caught or declared when calling the sleep method?

Accepted Answer

A)   IOException
B)   IllegalStateMonitorException
C)   InterruptedException
D)   SleepException

Question 5

Insert the statement that would start the following thread. Thread firstThread = new Thread(myRunnable);
____________________

Accepted Answer

A)   firstThread.run() ;
B)   firstThread.start() ;
C)   run() ;
D)   start() ;

Question 6

Which of the following definitely indicates that a thread has terminated?
I The run method has completed
II The method Thread.interrupted returns true
III The run method catches an InterruptedException

Accepted Answer

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

Question 7

Which of the following does not create an object that can run in a thread, assuming the following MyRunnable class declaration? public class MyRunnable implements Runnable { . . . }
I Runnable runnable = new Runnable();
II Runnable runnable = new MyRunnable();
III MyRunnable runnable = new MyRunnable();

Accepted Answer

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

Question 8

Consider the following change to the deposit method in Section 21.4: public void deposit(double amount)
{
BalanceChangeLock.lock();
Try
{
Double newBalance = balance + amount;
Balance = newBalance;
}
Finally
{
BalanceChangeLock.unlock();
}
System.out.println("Depositing " + amount + ", new balance is " + balance);
}
What is the consequence of this change?

Accepted Answer

A)   The bank account balances may no longer be correctly updated.
B)   The printouts may become intermingled.
C)   The printouts may no longer display the correct balances.
D)   All of the above.

Question 9

To start a thread, you should first construct an object from a class that implements the ____________ interface.

Accepted Answer

A)   Thread
B)   Threadable
C)   Run
D)   Runnable

Question 10

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

Accepted Answer

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

Question 11

The sleep method is terminated with a(n) __________ whenever a sleeping thread is interrupted.

Accepted Answer

A)   InterruptedException
B)   SleepException
C)   lock
D)   SignalException

Question 12

Assume two threads share a BankAccount object with balance of zero (0), and that the BankAccount class provides synchronized deposit and withdraw methods. Thread one deposits $10 ten times and, concurrently, thread two withdraws $10 ten times. Which statement regarding the balance after all thread calls is definitely true? public synchronized void deposit(int dollars)
{
Int newBalance = balance + dollars;
System.out.println("depositing");
Balance = newBalance;
}
Public synchronized void withdraw(int dollars)
{
Int newBalance = balance - dollars;
System.out.println("withdrawing");
Balance = newBalance;
}

Accepted Answer

A)   The balance could be zero or positive.
B)   The balance is zero.
C)   The balance could be zero or negative.
D)   The balance is positive.

Question 13

When a sleeping thread is interrupted, a(n) ____________________ is generated.

Accepted Answer

A)   ThreadInterruptedException
B)   ThreadException
C)   ThreadSleepException
D)   InterruptedException

Question 14

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

Question 15

Which of the following definitely indicates that a thread has been interrupted by another thread?
I The run method has completed
II The method Thread.interrupted returns true
III The run method catches an InterruptedException

Accepted Answer

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

Question 16

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 17

What happens when a thread calls the signalAll method of a Condition object connected to a lock, if no other thread had called await on that Condition object?

Accepted Answer

A)   A compiler error.
B)   A checked exception is thrown.
C)   The unlock method call will block.
D)   Nothing, the program executes normally.

Question 18

Which argument(s) present(s) the best case(s) for using the Runnable interface rather than extending the Thread class?
I Thread sub-classes are harder to write
II Runnable objects can be passed into thread pools
III Less time is wasted in creating and destroying thread objects

Accepted Answer

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

Question 19

____ allow a thread to temporarily release a lock, so that another thread can proceed, and to regain the lock at a later time.

Accepted Answer

A)   Condition objects
B)   Embedded systems
C)   Exceptions
D)   Race conditions

Question 20

Under what circumstances will a call to signalAll not release a blocked thread that has called await?

Accepted Answer

A)   When the thread is sleeping.
B)   When the thread called await on different condition object.
C)   When two or more threads are waiting.
D)   When the thread called await on the same condition object.

Exam 21: Multithreading

The thread that calls signalAll must own the lock that belongs to the condition object on which signalAll is called. Otherwise, a(n) _ __ is thrown.

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

The _____________ interface 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.

Which exception must be caught or declared when calling the sleep method?

Insert the statement that would start the following thread. Thread firstThread = new Thread(myRunnable) ; ____________________

Which of the following definitely indicates that a thread has terminated? I The run method has completed II The method Thread.interrupted returns true III The run method catches an InterruptedException