Deck 5: Loops and Files

Question 1

The for loop is a posttest loop that has built-in expressions for initializing, testing, and updating.

Answer 1

False

Question 2

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

Answer 2

False

Question 3

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.

Answer 3

False

Question 4

A __________ loop will always be executed at least once.

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

Question 5

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

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

Question 6

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

Question 7

You can use the PrintWriter class to open a file and write data to it.

Question 8

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 9

In general, there are two types of files which are

A) encrypted and unencrypted
B) delimited and unlimited
C) text and binary
D) static and dynamic

Question 10

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 11

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 12

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 13

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 14

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

Question 15

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

Question 16

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 17

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

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

Question 18

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

Question 19

An item that separates other items is known as a

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

Question 20

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

Question 21

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 22

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 23

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 24

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 25

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 26

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 27

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 28

What does the following code do? Scanner keyboard = new Scanner(System.in);
String filename;
System.out.print("Enter the filename: ");
Filename = keyboard.readString();
PrintWriter outFile = new PrintWriter(filename);

A) It writes to a file named filename.
B) It allows the user to enter the name of the file that data will be written to.
C) It establishes a connection with a file named filename.
D) Nothing; the code contains a syntax error.

Question 29

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 30

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

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

Question 31

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 32

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 33

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 34

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 35

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 36

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 37

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 38

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 39

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 40

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