ITP 120 Chapter 4

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

110

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

12

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

15

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; }

210

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

FALSE

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

FALSE

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

FALSE

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.

FALSE

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(); }

Impossible - the boolean condition can never be true

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(); }

Numbers in the range 100 - 500

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

TRUE

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

TRUE

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

TRUE

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

TRUE

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.

TRUE

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

a way to terminate

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

accumulator

An item that separates other items is known as a

delimiter

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

diskOut.println("Calvin");

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

do-while

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?

int number = inputFile.nextInt();

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

iteration

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

loop

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

this is an infinite loop

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;

40

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

loop control variable

A __________ loop will always be executed at least once.

posttest

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

sentinel

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.

sentinel

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

set the accumulator variable to an initial value, often zero

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

x = 33, y = 9

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

5 times

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.

TRUE

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

1 time

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

for

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

import java.io.*;

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

infinite

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?

while (inputFile.hasNext()) { ... }

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

Which of the following are pre-test loops?

while, for

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

x = 17, y = 4

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

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

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

FileWriter fwriter = new FileWriter("MyFile.txt", true); PrintWriter outFile = new PrintWriter(fwriter);

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

conditional

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

Random myNumber = new Random();

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

count-controlled

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

28

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

3

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

5, 8, 11, 14

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

TRUE

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.

TRUE

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

myNumber = randomNumbers.nextInt(10) + 1;

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

nextDouble() nextFloat()

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

the File class's exists method

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

user controlled loop