Deck 4: Loops and Files

Question 1

The do-while loop must be terminated with a semicolon.

Answer 1

True

Question 2

A(n) __________ is a special value that cannot be mistaken as a member of a list of data items and signals that there are no more data items to be processed.

A) accumulator
B) sentinel
C) delimiter
D) terminator

Answer 2

B

Question 3

In a for loop, the control variable is always incremented.

Answer 3

False

Question 4

The do-while loop is ideal in situations where you always want the loop to iterate at least once.

Question 5

A loop that executes as long as a particular condition exists is called a(n) __________ loop.

A) infinite
B) count-controlled
C) conditional
D) relational

Question 6

When the continue statement is encountered in a loop, all the statements in the body of the loop that appear after it are ignored, and the loop prepares for the next iteration.

Question 7

When you open a file with the PrintWriter class, the class can potentially throw an IOException.

Question 8

When you pass the name of a file to the PrintWriter constructor and the file already exists, it will be erased and a new empty file with the same name will be created.

Question 9

An item that separates other items is known as a

A) partition
B) delimiter
C) sentinel
D) terminator

Question 10

A loop that repeats a specific number of times is known as a(n) __________ loop.

A) count-controlled
B) infinite
C) conditional
D) pretest

Question 11

A __________ loop will always be executed at least once.

A) pretest
B) posttest
C) conditional
D) user-controlled

Question 12

When the break statement is encountered in a loop, all the statements in the body of the loop that appear after it are ignored, and the loop prepares for the next iteration.

Question 13

The variable used to keep a running total in a loop is called a(n) __________.

A) accumulator
B) sentinel
C) summation
D) integer

Question 14

Java provides a set of simple unary operators designed just for incrementing and decrementing variables.

Question 15

In a for loop, the control variable cannot be initialized to a constant value and tested against a constant value.

Question 16

Before entering a loop to compute a running total, the program should first

A) set the accumulator variable to an initial value, often zero
B) set all variables to zero
C) read all the values into main memory
D) know exactly how many values there are to total

Question 17

The while loop is always the best choice in situations where the exact number of iterations is known.

Question 18

The while loop has two important parts: (1) a boolean expression that is tested for a true or false value, and (2) a statement or block of statements that is repeated as long as the expression is true.

Question 19

A file must always be opened before using it and closed when the program is finished using it.

Question 20

A __________ is a value that signals when the end of a list of values has been reached.

A) terminal
B) sentinel
C) token
D) delimiter

Question 21

When working with the PrintWriter class, which of the following import statements should you have near the top of your program?

A) import javax.swing.*;
B) import javac.io.*;
C) import java.io.*;
D) import java.file.*;

Question 22

How many times will the following do-while loop be executed?
int x = 11;
Do
{
X += 20;
} while (x > 100);

A) 0
B) 1
C) 5
D) 4

Question 23

The __________ loop is ideal in situations where you always want the loop to iterate at least once.

A) for
B) while
C) do-while
D) posttest

Question 24

What will be the value of x after the following code is executed?
int x, y = 4, z = 6;
X = (y++) * (++z);

A) 24
B) 28
C) 30
D) 35

Question 25

Which of the following is the method you can use to determine whether a file exists?

A) the File class's canOpen method
B) the Scanner class's exists method
C) the File class's exists method
D) the PrintWriter class's fileExists method

Question 26

If a loop does not contain, within itself, a valid way to terminate, it is called a(n) __________ loop

A) for
B) while
C) do-while
D) infinite

Question 27

In all but very rare cases, loops must contain, within themselves

A) nested loops
B) a way to terminate
C) arithmetic operators
D) nested decision strucures

Question 28

Which of the following statements opens a file named MyFile.txt and allows you to read data from it?

A) Scanner inputFile = new Scanner("MyFile.txt");
B) File file = new File("MyFile.txt");
Scanner inputFile = new Scanner(file);
C) File Scanner = new File("MyFile.txt");
D) PrintWriter inputFile = new PrintWriter("MyFile.txt");

Question 29

What will be the value of x after the following code is executed?
int x, y = 15;
X = y--;

A) 14
B) 16
C) 0
D) 15

Question 30

What will be the value of x after the following code is executed?
int x = 10;
While (x < 100)
{
X += 100;
}

A) 100
B) 90
C) 110
D) 10

Question 31

What will be the value of x after the following statements are executed?
int x = 10;
For (int y = 5; y < 20; y +=5)
X += y;

A) 25
B) 30
C) 50
D) 40

Question 32

Given the following statement, which statement will write the string "Calvin" to the file DiskFile.txt?
PrintWriter diskOut = new PrintWriter("DiskFile.txt");

A) System.out.println(diskOut, "Calvin");
B) PrintWriter.println("Calvin");
C) DiskFile.println("Calvin");
D) diskOut.println("Calvin");

Question 33

What will be the values of x and y as a result of the following code?
int x = 25, y = 8;
X += y++;

A) x = 34, y = 9
B) x = 25, y = 8
C) x = 33, y = 8
D) x = 33, y = 9

Question 34

How many times will the following do-while loop be executed?
int x = 11;
Do
{
X += 20;
} while (x <= 100);

A) 5
B) 4
C) 3
D) 1

Question 35

Assume that inputFile references a Scanner object that was used to open a file. Which of the following while loops is the correct way to read data from the file until the end of the file is reached?

A) while (inputFile.nextLine == " ")
{ ).. }
B) while (inputFile != null)
{ ).. }
C) while (!inputFile.EOF)
{ ).. }
D) while (inputFile.hasNext())
{ ).. }

Question 36

What will be printed after the following code is executed? for (int number = 5; number <= 15; number +=3)
System.out.print(number + ", ");

A) 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
B) 5, 8, 11, 14, 17,
C) 5, 8, 11, 14
D) This is an invalid for statement.

Question 37

The __________ loop is ideal in situations where the exact number of iterations is known.

A) for
B) while
C) do-while
D) posttest

Question 38

How many times will the following for loop be executed?
for (int count = 10; count <= 21; count++)
System.out.println("Java is great!");

A) 0
B) 12
C) 10
D) 11

Question 39

Which of the following statements opens a file named MyFile.txt and allows you to append data to its existing contents?

A) FileWriter fwriter = new FileWriter("MyFile.txt");
PrintWriter outFile = new PrintWriter(fwriter);
B) FileWriter fwriter = new FileWriter("MyFile.txt", true);
PrintWriter outFile = new PrintWriter(fwriter);
C) PrintWriter outfile = new PrintWriter("MyFile.txt", true);
D) PrintWriter outfile = new PrintWriter(true, "MyFile.txt");

Question 40

Assuming that inputFile references a Scanner object that was used to open a file, which of the following statements will read an int from the file?

A) int number = inputFile.next();
B) int number = inputFile.integer();
C) int number = inputFile.readInt();
D) int number = inputFile.nextInt();

Question 41

What will be the values of x aand y after the following code is executed? int x = 12, y = 5;
X += y--;

A) x = 12, y = 5
B) x = 16, y = 4
C) x = 17, y = 5
D) x = 17, y = 4

Question 42

What will be the values of x and y after the following code is executed? int x, y = 15, z = 3;
X = (y--) / (++z);

A) 3
B) 4
C) 5
D) 6

Question 43

Which is a control structure that causes a statement or group of statements to repeat?

A) block
B) loop
C) prefix mode
D) body

Question 44

Select all that apply. Which method of the Random class will return a random number within the range of 0.0 and 1.0?

A) nextDouble()
B) nextLong()
C) nextFloat()
D) nextInt(int n)

Question 45

Which of the following statements will create an object from the Random class?

A) randomNumbers() = new Random();
B) Random myNumber = new Random();
C) myNumber = new Random();
D) Random = new randomNumbers();

Question 46

Which of the following are pre-test loops?

A) while, for, do-while
B) while, do-while
C) while, for
D) for, do-while

Question 47

Select all that apply. Which of the following steps is normally performed by a for loop?

A) update the control variable during each iteration
B) test the control variable by comparing it to a maximum or minimum value
C) terminate when the control variable reaches its maximum or minimum value
D) initialize the control variable to a starting value

Question 48

A random number, created as an object of the Random class, is always a(n) __________.

A) object
B) integer
C) float
D) class

Question 49

What will be the value of x after the following code is executed?
int x = 10, y = 20;
While (y < 100)
{
X += y;
}

A) 90
B) 110
C) 210
D) this is an infinite loop

Question 50

In the following code, what values could be read into number to terminate the while loop? Scanner keyboard = new Scanner(System.in);
System.out.print("Enter a number: ");
Int number = keyboard.nextInt();
While (number < 100 && number > 500)
{
System.out.print("Enter another number: ");
Number = keyboard.nextInt();
}

A) Numbers less than 100 or greater than 500
B) Numbers in the range 100 - 499
C) Numbers in the range 100 - 500
D) Impossible - the boolean condition can never be true

Question 51

The variable that controls the number of times a loop iterates is known as a(n) __________.

A) counter variable
B) loop control variable
C) running total
D) decrement variable

Question 52

In the following code, what values could be read into number to terminate the while loop? Scanner keyboard = new Scanner(System.in);
System.out.print("Enter a number: ");
Int number = keyboard.nextInt();
While (number < 100 || number > 500)
{
System.out.print("Enter another number: ");
Number = keyboard.nextInt();
}

A) Numbers less than 100
B) Numbers greater than 500
C) Numbers in the range 100 - 499
D) Numbers in the range 100 - 500

Question 53

What will be the value of x after the following code is executed?
int x = 10, y = 20;
While (y < 100)
{
X += y;
Y += 20;
}

A) 130
B) 210
C) 110
D) 90

Question 54

Each repetition of a loop is known as a(n) __________.

A) iteration
B) cycle
C) execution
D) lap

Question 55

The __________ loop allows the user to decide on the number of iterations.

A) counter controlled loop
B) dynamically executed loop
C) user controlled loop
D) infinite loop

Question 56

Which of the following expressions will generate a random number in the range of 1 through 10?

A) myNumber = randomNumbers.nextInt(10);
B) myNumber = randomNumbers.nextInt(1) + 10;
C) myNumber = randomNumbers.nextInt(11) - 1;
D) myNumber = randomNumbers.nextInt(10) + 1;