Deck 3: Introduction to Classes and Objects

Question 1

A default constructor has how many parameters?

A)0.
B)1.
C)2.
D)a variable number.

Answer 1

A

Question 2

What is the difference between a float and a double?

A)double variables store integers and float variables store floating-point numbers.
B)double variables store numbers with smaller magnitude and coarser detail.
C)double variables store numbers with larger magnitude and finer detail.
D)None of the above.

Answer 2

C

Question 3

Which of the following is a valid fully qualified name?

A)Scanner.
B)java.Scanner.
C)util.Scanner.
D)java.util.Scanner.

Answer 3

D

Question 4

Which of the following is a Scanner method?

A)nextLine.
B)nextText.
C)nextWord.
D)readNext.

Question 5

What is the default value of a reference?

A)0.
B)"".
C)null.
D)default.

Question 6

A class instance creation expression contains:

A)Parentheses.
B)The new keyword.
C)The name of the class.
D)All of the above.

Question 7

How many significant digits does a double variable have?

A)7.
B)8.
C)14.
D)15.

Question 8

Which class provides prebuilt dialog boxes that enable programs to display windows containing messages (such windows are called message dialogs)?

A)JDialogBox.
B)JPrebuiltDialog.
C)JMessageDialog.
D)JOptionPane.

Question 9

What type of methods allow a client of a class to assign values to a private instance variable?

A)Get methods.
B)Replace methods.
C)Assign methods.
D)Set methods.

Question 10

Which of the following statements is false?

A)You must create an object of class JOptionPane to use its static method showMessageDialog.
B)JOptionPane method showInputDialog displays an input dialog containing a prompt and a field (known as a text field)in which a user can enter text.
C)String method format works like method System.out.printf,except that format returns the formatted String rather than displaying it in a command window.
D)An input dialog allows the user to enter data into a program.

Question 11

Method headers contain all of the following except:

A)Access modifier.
B)Left brace.
C)Name of method.
D)Return type.

Question 12

Multiple parameters are separated with what symbol?

A)Dot separator
B)Comma.
C)Parentheses.
D)Braces.

Question 13

How many significant digits does a double variable have?

A)7.
B)8.
C)14.
D)15.

Question 14

Which two Java primitive types store floating-point numbers?

A)decimal and float.
B)point and double.
C)float and double.
D)decimal and point.

Question 15

Which class provides prebuilt dialog boxes that enable programs to display windows containing messages (such windows are called message dialogs)?

A)JDialogBox.
B)JPrebuiltDialog.
C)JMessageDialog.
D)JOptionPane.

Question 16

What is the default initial value of a String instance variable?

A)""
B)"default"
C)default
D)null

Question 17

Attributes of a class are also known as:

A)Constructors.
B)Local variables.
C)Fields.
D)Classes.

Question 18

What is the name of the values the method call passes to the method for the parameters?

A)Arguments.
B)References.
C)Objects.
D)Values.