chapter 3

Which of the following are so called short-circuit operators?

&& ||

Which of the Boolean expressions below is incorrect?

(true) && (3 => 4) (x != 0) || (x = 0) (-10 < x < 0)

Suppose x=10 and y=10. What is x after evaluating the expression (y >= 10) || (x++ > 10).

10

Analyze the following code fragments that assign a boolean value to the variable even. Code 1: if (number % 2 == 0) even = true; else even = false; Code 2: even = (number % 2 == 0) ? true: false; Code 3: even = number % 2 == 0;

All three are correct, but Code 3 is preferred.

Code 1: int number = 45; boolean even; if (number % 2 == 0) even = true; else even = false; Code 2: int number = 45; boolean even = (number % 2 == 0);

Both Code 1 and Code 2 are correct, but Code 2 is better.

Which of the following is equivalent to x != y?

! (x == y) x > y || x < y

Which of the following is the correct expression that evaluates to true if the number x is between 1 and 100 or the number is negative?

((x < 100) && (x > 1)) || (x < 0)

Suppose x=10 and y=10. What is x after evaluating the expression (y > 10) && (x++ > 10).

10

Suppose x=10 and y=10. What is x after evaluating the expression (y > 10) && (x-- > 10)?

10

Suppose x=10 and y=10. What is x after evaluating the expression (y >= 10) || (x-- > 10).

10

What is y after the following switch statement is executed? int x = 3; int y = 4; switch (x + 3) { case 6: y = 0; case 7: y = 1; default: y += 1; }

2

The "less than or equal to" comparison operator in Java is __________.

<=

Which of the following operators are right-associative.

=

The equal comparison operator in Java is __________.

==

Analyze the following code: boolean even = false; if (even = true) { System.out.println("It is even"); }

The program runs fine and displays It is even.

Analyze the following program fragment: int x; double d = 1.5; switch (d) { case 1.0: x = 1; case 1.5: x = 2; case 2.0: x = 3;

The switch control variable cannot be double.

What is 1 - 0.1 - 0.1 - 0.1 - 0.1 - 0.1 == 0.5?

There is no guarantee that 1 - 0.1 - 0.1 - 0.1 - 0.1 - 0.1 == 0.5 is true.

The following code displays ___________. double temperature = 50; if (temperature >= 100) System.out.println("too hot"); else if (temperature <= 40) System.out.println("too cold"); else System.out.println("just right");

just right

What is 1 + 1 + 1 + 1 + 1 == 5?

true

true || true && false

true

Assume x = 4 and y = 5, which of the following is true?

x != 4 ^ y == 5

Assume x = 4, which of the following is true?

x != 5

Given |x| >= 4, which of the following is true?

x >= 4 || x <= -4

What is the output of the following code?

x is 1

Which of the following statements are true?

(x > 0 && x < 10) is same as ((x > 0) && (x < 10)) (x > 0 || x < 10) is same as ((x > 0) || (x < 10)) (x > 0 || x < 10 && y < 0) is same as (x > 0 || (x < 10 && y < 0))

The order of the precedence (from high to low) of the operators binary +, *, &&, ||, ^ is:

*, +, ^, &&, ||

What is y after the following statement is executed? x = 0; y = (x > 0) ? 10 : -10;

-10

What is the output from System.out.println((int)Math.random() * 4)?

0

What is the possible output from System.out.println((int)(Math.random() * 4))?

0, 1, 2, 3

Which of the following is a possible output from invoking Math.random()?

0.5, 0.0

Suppose you write the code to display "Cannot get a driver's license" if age is less than 16 and "Can get a driver's license" if age is greater than or equal to 16. Which of the following code is correct? I: if (age < 16) System.out.println("Cannot get a driver's license"); if (age >= 16) System.out.println("Can get a driver's license"); II: if (age < 16) System.out.println("Cannot get a driver's license"); else System.out.println("Can get a driver's license"); III: if (age < 16) System.out.println("Cannot get a driver's license"); else if (age >= 16) System.out.println("Can get a driver's license"); IV: if (age < 16) System.out.println("Cannot get a driver's license"); else if (age > 16) System.out.println("Can get a driver's license"); else if (age == 16) System.out.println("Can get a driver's license");

I, II, III, IV

Suppose you write the code to display "Cannot get a driver's license" if age is less than 16 and "Can get a driver's license" if age is greater than or equal to 16. Which of the following code is the best? I: if (age < 16) System.out.println("Cannot get a driver's license"); if (age >= 16) System.out.println("Can get a driver's license"); II: if (age < 16) System.out.println("Cannot get a driver's license"); else System.out.println("Can get a driver's license"); III: if (age < 16) System.out.println("Cannot get a driver's license"); else if (age >= 16) System.out.println("Can get a driver's license"); IV: if (age < 16) System.out.println("Cannot get a driver's license"); else if (age > 16) System.out.println("Can get a driver's license"); else if (age == 16) System.out.println("Can get a driver's license");

II

Suppose income is 4001, what is the output of the following code? if (income > 3000) { System.out.println("Income is greater than 3000"); } else if (income > 4000) { System.out.println("Income is greater than 4000"); }

Income is greater than 3000

The __________ method immediately terminates the program.

System.exit(0);

boolean even = false; if (even) { System.out.println("It is even!"); }

The code displays nothing

Suppose isPrime is a boolean variable, which of the following is the correct and best statement for testing if isPrime is true?

if (isPrime)

Which of the following code displays the area of a circle if the radius is positive?if (radius > 0)

if (radius > 0) System.out.println(radius * radius * 3.14159);

Analyze the following code: if (x < 100) && (x > 10) System.out.println("x is between 10 and 100");

The statement has compile errors because (x<100) & (x > 10) must be enclosed inside parentheses.

In Java, the word true is ________.

a Boolean literal

boolean even = false; System.out.println((even ? "true" : "false"));

false

Suppose x = 1, y = -1, and z = 1. What is the output of the following statement? (Please indent the statement correctly first.) if (x > 0) if (y > 0) System.out.println("x > 0 and y > 0"); else if (z > 0) System.out.println("x < 0 and z > 0");

x < 0 and z > 0;

Assume x = 4 and y = 5, which of the following is true?

x < 5 || y < 5

Given |x| <= 4, which of the following is true?

x <= 4 && x >= -4

public class Test1 { public static void main(String[] args) { int x = 1; int y = x = x + 1; System.out.println("y is " + y); } }

y is 2 because x + 1 is assigned to x and then x is assigned to y.