Deck 5: Defining Classes II

Question 1

A class that contains public methods that can change the data in the object of a class is called a/an:

A)mutable class
B)immutable class
C)invariant class
D)none of the above

Answer 1

A

Question 2

When you use the assignment operator with variables of a class type,you are assigning a:

A)value
B)primitive type
C)local variable
D)reference

Answer 2

D

Question 3

A condition that allows a programmer to circumvent the private modifier and change the private instance variable is called:

A)a copy constructor
B)a privacy leak
C)a class invariant
D)an anonymous object

Answer 3

B

Question 4

The conversion from an object of a wrapper class to a value of its associated primitive type is called:

A)Boxing
B)Unboxing
C)Converting
D)Reinstantiating

Question 5

The Math method that returns the nearest whole number that is greater than or equal to its argument is:

A)round
B)ceil
C)floor
D)all of the above

Question 6

A copy constructor has _________ parameters.

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

Question 7

All of these are methods of Java's Math class except:

A)pow
B)min
C)random
D)toString

Question 8

Only ______ copy/copies of a static variable are available to objects of a class.

A)one
B)two
C)three
D)none of the above

Question 9

The program included in the Java SDK that allows a programmer to separate the class interface from the class implementation is called:

A)javac
B)java
C)javadoc
D)none of the above

Question 10

Converting from a value of primitive type to a corresponding object of its associated wrapper class is called:

A)Boxing
B)Unboxing
C)Converting
D)Reinstantiating

Question 11

A static method is one that can be used with a _____________.

A)instance variable
B)local variable
C)global variable
D)the class name as a calling object

Question 12

A main method can be placed inside a class definition.

Question 13

The method trim of the String class trims off:

A)Leading white space
B)Trailing white space
C)Leading and trailing white space
D)Blanks

Question 14

To create a package,you must add a package statement at the ____________ of each class file.

A)beginning
B)end
C)before each method signature
D)after the import statements

Question 15

null can be used:

A)to indicate a variable has no real value
B)in a Boolean expression with ==
C)as a placeholder
D)all of the above

Question 16

Javadoc requires a comment to be delimited by _________ to be included in the extracted class interface.

A)// //
B)/* */
C)/** */
D)" "

Question 17

An example of secondary memory is:

A)RAM
B)ROM
C)hard disk
D)all of the above

Question 18

All of the following are wrapper classes except:

A)String
B)Integer
C)Character
D)Double

Question 19

In a static method,you may use the this parameter either explicitly or implicitly.

Question 20

Static variables are often used:

A)in arithmetic expressions
B)to communicate between objects
C)within looping structures
D)all of the above

Question 21

All versions of Java support automatic boxing.

Question 22

Write a statement that creates and initializes a static variable named salesTax to 7.59.

Question 23

Wrapper classes are provided for all primitive Java types except Boolean.

Question 24

Wrapper classes provide a class type corresponding to each of the primitive types so that you can have class types that behave somewhat like primitive types.

Question 25

The String class is a mutable class.

Question 26

Write a Java method that returns true if and only if a character is a digit or a letter.The method should display appropriate feedback to the console.

Question 27

Define boxing and unboxing.

Question 28

To use a package,the program must contain an import statement that names the package.

Question 29

You may use methods of the Math class without an import statement.

Question 30

Write ONE Java statement that computes and displays a random number between 1 and 25.

Question 31

A bit may have the value of either a 1 or 0.

Question 32

Deprecated methods should be used in new Java code.

Question 33

You should avoid the use of null as an argument to a method.

Question 34

When used with objects,what is the equality == )operator really comparing?

Question 35

A class invariant is a statement that is always true for every object of the class.

Question 36

How many bytes are contained within 16-bits,32-bits,64-bits?

Question 37

Write ONE Java statement that computes and displays the value of 2< sup >5< /sup >.

Question 38

Explain in detail how main memory works.

Question 39

Write a statement that creates a constant variable named TAX_RATE.The tax rate is 8.25%.

Question 40

Primitive types are reference types.

Question 41

Does an object created with a copy constructor reference the same memory location that the original object references? Explain.

Question 42

Add a constructor and a copy constructor to the Book class created in question #13.

Question 43

Add accessor and mutator methods to the Book class created in question #13.

Question 44

Explain how a package is named in Java.

Question 45

Create a Java class named Book with instance variables title,author,ISBN,and yearPublished.Include javadoc style comments to describe your interface.Such a class would normally have methods,but you are not required to supply any methods.

Question 46

What is the purpose of Java's wrapper classes?