Chapter 2 - Elementary Programming

Question 1

What are “identifiers”?

Answer 1

Identifiers are names for naming elements such as variables, constants, methods, classes, packages in a program

Question 2

What are the naming rules for identifiers?

Answer 2

1. Can be letters, digits, underscores and dollar signs
2. Must begin with letter or underscore.
3. Can not be a reserved word.

Question 3

What is a named constant?

Answer 3

A named constant represents permanent data that never changes

Question 4

How is a named constant declared?

Answer 4

By using the keyword “final”

Question 5

What are the integer types in Java?

Answer 5

byte, short, int, and long. Representing different sizes in ascending order

Question 6

What are the floating-point types in Java?

Answer 6

They are float and double, representing two different presicions

Question 7

How can you convert a value from one type to another?

Answer 7

You can do this explicitly by using the (type)value notation

Question 8

What does it mean to widen a type?

Answer 8

Casting a variable of a type with a small range to a variable of a type with a larger range

Question 9

What does it mean to narrow a type?

Answer 9

Casting a variable of a type with a large range to a variable of a type with a smaller range

Question 10

what is “char”?

Answer 10

A reserved word, and a type that represents a single character

Question 11

What is the UNIX epoch?

Answer 11

Midnight of January 1, 1970 is known as the UNIX epoch. System.currentTimeMillis() returns the number of milliseconds since the UNIX epoch

Question 12

Which of the following are correct ways to declare variables?
A. int length; int width;
B. int length, width;
C. int length; width;
D. int length, int width;

Answer 12

A and B are correct

Question 13

To improve readability and maintainability, you should declare ____ instead of using literal values such as 3.14159

Answer 13

Constants

Question 14

Which of these data types requires the most amount of memory?
A. long
B. int
C. short
D. byte

Answer 14

long

Question 15

If a number is too large to be stored in a variable of the float type, it \_\_\_
A. causes overflow
B. causes underflow
C. causes no error
D. cannot happen in Java

Answer 15

It causes overflow

Question 16

Analyze the following code:

public class Test {
  public static void main(String[] args) {
    int n = 10000 * 10000 * 10000;
    System.out.println("n is " + n);
  }
}

A. The program displays n is 1000000000000
B. The result of 10000 * 10000 * 10000 is too large to be stored in an int variable n. This causes an overflow and the program is aborted.
C. The result of 10000 * 10000 * 10000 is too large to be stored in an int variable n. This causes an overflow and the program continues to execute because Java does not report errors on overflow.
D. The result of 10000 * 10000 * 10000 is too large to be stored in an int variable n. This causes an underflow and the program continues to execute because Java does not report errors on underflow.

Answer 16

Correct answer is C:
The result of 10000 * 10000 * 10000 is too large to be stored in an int variable n. This causes an overflow and the program continues to execute because Java does not report errors on overflow.

Question 17

Which of the following expression results in a value 1?
A. 2 % 1
B. 15 % 4
C. 25 % 5
D. 37 % 6

Answer 17

D. 37 % 6

Question 18

-24 % 5 is \_\_\_
A. 1
B. -1
C. 4
D. -4

Answer 18

D. -4

Question 19

-24 % -5 is \_\_
A. 1
B. -1
C. 4
D. -4

Answer 19

D. -4

Question 20

Math.pow(2, 3) returns \_\_
A. 9
B. 8
C. 9.0
D. 8.0

Answer 20

D. 8.0

Math.pow() returns a double value

Question 21

Analyze the following code.

public class Test {
  public static void main(String[] args) {
    int month = 09;
    System.out.println("month is " + month);
  }
}

A. The program displays month is 09
B. The program displays month is 9
C. The program displays month is 9.0
D. The program has a syntax error, because 09 is an incorrect literal value.

Answer 21

D. The program has a syntax error, because 09 is an incorrect literal value.
Explanation: Any numeric literal with the prefix 0 is an octal value. But 9 is not an octal digit. An octal digit is 0, 1, 2, 3, 4, 5, 6, or 7.

Question 22

The expression 4 + 20 / (3 - 1) * 2 is evaluated to

A. 4
B. 20
C. 24
D. 9
E. 25

Answer 22

C. 24

Question 23

To assign a double variable d to a float variable x, you write

Answer 23

x = (float)d;

Question 24

Note that the Unicode for character A is 65. The expression "A" + 1 evaluates to \_\_
A. 66
B. B
C. A1
D. Illegal expression

Answer 24

C. A1