Deck 5: Loops and Files

Question 1

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");

Answer 1

B

Question 2

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

Answer 2

B

Question 3

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

Answer 3

D

Question 4

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) pretest

Question 5

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

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

Question 6

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 7

This type of loop will always be executed at least once.

A) pretest
B) posttest
C) infinite
D) conditional

Question 8

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 9

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 10

Assume that inputFile references a Scanner object that was used to open a file. Which of the following while loops shows 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 11

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 to be written to.
C) It establishes a connection with a file named filename.
D) Nothing. The code contains a syntax error.

Question 12

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 13

A for loop normally performs which of these steps?

A) update the control variable during each iteration
B) test the control variable by comparing it to a maximum/minimum value and terminate when the variable reaches that value
C) initialize a control variable to a starting value
D) All of the above

Question 14

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

A) set the accumulator variable to an initial value, usually 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 15

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 16

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

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

Question 17

This is an item that separates other items.

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

Question 18

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

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

Question 19

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 20

You can use this method 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 21

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

Question 22

The variable used to keep the running total is called a(n)

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

Question 23

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

Question 24

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

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

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

Question 27

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 28

In all but rare cases, loops must contain within themselves

A) nested loops.
B) a way to terminate.
C) arithmetic operators.
D) if statements.

Question 29

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 30

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 31

In a for loop, the control variable can only be incremented.

Question 32

In general, there are two types of files:

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

Question 33

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 34

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 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 file = new File("MyFile.txt");
D) PrintWriter inputFile = new PrintWriter("MyFile.txt");

Question 36

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 from the list to be processed.

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

Question 37

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

Question 38

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

Question 39

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 40

If a loop does not contain within itself a way to terminate, it is called

A) a for loop.
B) an infinite loop.
C) a while loop.
D) a do-while loop.