Deck 3: Introduction to Objects and Inputoutput

Question 1

The default output of decimal numbers of the type float is up to nine decimal places.

Answer 1

False

Question 2

String variables are reference variables.

Answer 2

True

Question 3

If length denotes the length of a nonnull string, then length - 1 gives the index of the last character in the string.

Answer 3

True

Question 4

String objects are mutable.

Question 5

Suppose z = 1834.762. The output of the statement System.out.printf("%.1f", z); is 1834.800.

Question 6

In the class String, the substring method inserts a string into another string.

Question 7

The method printf is used only to format the output of integers and decimal numbers.

Question 8

Reference type variables directly store data into their memory space.

Question 9

Given int num; the value of num is directly stored in its memory space.

Question 10

The new operator is used to create an int variable.

Question 11

In a format specifier, the option width specifies the maximum number of characters to be written to the output.

Question 12

The classes Integer, Float, and Double are called wrapper classes.

Question 13

In a string, the index (position) of the first character is 1.

Question 14

Suppose that name is a String variable. Then the following two statements are equivalent. name = "Danny"; name = new String("Danny");

Question 15

To use the contents of the java.lang package in a program, they must be imported using the import statement.

Question 16

Java provides automatic garbage collection.

Question 17

In a format specifier, if the flag is set to 'l', then the output of the result is left justified.

Question 18

In order to use a predefined method, you only need to know the name of the method and the type of each parameter.

Question 19

The value of the expression Integer.parseInt("+782") is "782".

Question 20

The dot (.) operator is also called the member specific operator.

Question 21

When writing output to a file, if the file is not closed at the end of the program, you may not be able to view your output properly.

Question 22

What will most probably happen if you omit the dot operator when accessing a method?

A) An exception will be thrown.
C) A syntax error will be reported.
B) The computer will crash.
D) The program will execute as planned.

Question 23

Which of the following is the member access operator?

A) +
C) -
B) .
D) ->

Question 24

In Java, all variables declared using a class are ____.

A) primitive variables
C) constants
B) reference variables
D) operators

Question 25

Given a decimal number, the method format of the class String returns the string containing the digits of the formatted number.

Question 26

The class JOptionPane allows a programmer to use graphical interface components to obtain input from a user.

Question 27

An expression such as str.length(); is an example of a(n) ____.

A) system call
C) class
B) object call
D) method call

Question 28

What is the value of the following statement? Math.pow(3,4)

A) 7
C) 34
B) 12
D) 81

Question 29

Suppose str is a String variable. The statement str = new String("Programming"); is similar to which of the following?

A) new String = "Programming";
B) String new = "Programming";
C) str = "Programming";
D) str new "Programming";

Question 30

Which package is automatically imported by the Java system?

A) java.io
C) java.util
B) java.lang
D) java.swing

Question 31

There are ____ type(s) of methods in a class.

A) one
C) three
B) two
D) four

Question 32

The statement System.exit(0); is found at the end of every working Java program.

Question 33

Which statement instructs a program to run the garbage collector?

A) System.clearGarbage();
B) System.flushGarbage();
C) System.out();
D) System.gc();

Question 34

Which of the following method is contained in the package java.util?

A) format
C) nextInt
B) Integer
D) printf

Question 35

Based on the code above, what is the value of str1?

A) exam i
C) exam is
B) exam
D) on Monday

Question 36

The class JOptionPane is part of the package java.swing.

Question 37

Suppose the String variable str points to the String object "Sunny day" at the memory address 3600. Then the value of str is:

A) the memory address 3600
C) 3600 + "Sunny day"
B) "Sunny day"
D) None of these

Question 38

Based on the code above, what is the value of str2?

A) Firs
C) Monda
B) First
D) exam

Question 39

Based on the code above, what is the value of length1?

A) 20
C) 24
B) 21
D) 26

Question 40

Which of the following is a valid statement? (i) int num = new int(67); (ii) String name = new ("Doe"); (iii) String name = "Doe";

A) Only (i)
C) Only (iii)
B) Only (i) and (ii)
D) Only (ii) and (iii)

Question 41

Suppose that you have the declaration: int num = 94; double x = 73.92; String str = "Programming"; What is the output of the following statements? System.out.println("123456789012345678901234567890"); System.out.printf("%5d%6.2f %15s%n", num, x, str);

A) 123456789012345678901234567890
B) 123456789012345678901234567890
C) 123456789012345678901234567890
D) 123456789012345678901234567890

Question 42

Based on the code above, what is the value of str3?

A) "First exam is on Monday."
B) "F#rst exam #s on Monday."
C) "F#rst exam is on Monday."
D) "#i### #### i###########."

Question 43

Consider the following statements. double x; String y; y = String.format("%.2f", x); If x = 285.679, what is the value of y?

A) "285.00"
C) "285.68"
B) "285.680"
D) "285.068"

Question 44

Which of the following outputs 56734.9875 to three decimal places?

A) System.out.printf("3f%", 56734.9875);
B) System.out.printf(".3f%", 56734.9875);
C) System.out.printf(".03f%", 56734.9875);
D) System.out.printf("%.3f", 56734.9875);

Question 45

The showMessageDialog method has ____ parameter(s).

A) one
C) three
B) two
D) four

Question 46

What is the output of the following statement? System.out.printf("%.2f", 48.9);

A) 48.00
C) 49
B) 48.90
D) 49.00

Question 47

Which of the following is an area of secondary storage used to hold information?

A) file
C) constant
B) variable
D) buffer

Question 48

Which of the following statements would store input in name?

A) name =
B) name =
C) name = System.in();
D) name = JOptionPane.input("Enter your name and press OK");

Question 49

What happens when JOptionPane.PLAIN_MESSAGE is chosen as the messageType parameter?

A) No icon is displayed in the dialog box.
B) An X is displayed in the dialog box.
C) A question mark is displayed in the dialog box.
D) An exclamation point is displayed in the dialog box.

Question 50

Based on the code above, what is the value of str4?

A) 11
C) 13
B) 12
D) 14