Deck 8: A Second Look at Classes and Objects

Question 1

A static field is created by placing:

A) the key word static after the field name
B) the key word static after the access specifier and before the field's data type
C) the key word static after the access specifier and field's data type
D) it in a static field block

Answer 1

B

Question 2

When a reference variable is passed as an argument to a method:

A) a copy of the variable's value is passed into the method's parameter
B) the method has access to the object that the variable references
C) the method becomes a static method
D) the program will terminate

Answer 2

B

Question 3

Which of the following is NOT true about static methods?

A) It is necessary for an instance of the class to be created to execute the method.
B) They are created by placing the key word static after the access specifier in the method header.
C) They are called directly from the class.
D) They are often used to create utility classes that perform operations on data, but have no need to collect and store data.

Answer 3

A

Question 4

The term for the relationship created by object aggregation is:

A) has a
B) is a
C) Sub-class object
D) Inner class

Question 5

If the this variable is used to call a constructor:

A) a compiler error will result, if it is not the first statement of the constructor
B) a compiler error will result, if it is the first statement of the constructor
C) nothing will happen
D) the this variable cannot be used as a constructor call

Question 6

If object1 and object2 are objects of the same class, to make object2 a copy of object1:

A) assign object1 to object2, such as object2 = object1;
B) write a copy method that will make a field by field copy of object1 data members into object2 data members
C) use the Java copy method that is a part of the Java language
D) use the default constructor to create object2 with object1 data members

Question 7

In Java, it is possible to write a method that will return:

A) a whole number
B) a monetary value
C) a string of characters
D) a reference to an object
E) All of the above

Question 8

You cannot use the == operator to compare the contents of:

A) objects
B) strings
C) integers
D) Boolean values

Question 9

When a field is declared static, there will be:

A) a copy of the field in each class object
B) only one copy of the field in memory
C) a copy of the field for each static method in the class
D) only two copies of the field in memory

Question 10

Java automatically stores this value in all uninitialized static member variables:

A) 0
B) -1
C) null
D) False

Question 11

To compare two objects in a class:

A) use the == operator, e.g. object1 == object2
B) write a method to do a byte-by-byte compare of the two objects
C) write an equals method that will make a field by field compare of the two objects
D) Since objects consist of several fields, you cannot compare them

Question 12

Static methods can only operate on ________ fields.

A) instance
B) static
C) global
D) local

Question 13

If the following is from the method section of a UML diagram, which of the following statements is TRUE?
+ equals(object2:Stock) : boolean

A) This is a private method that receives two objects from the Stock class and returns a boolean value.
B) This is a public method that accepts a Stock object as its argument and returns a boolean value.
C) This is a private method that returns a boolean value.
D) This is a public method that returns a Stock object.

Question 14

When a method's return type is a class, what is actually returned to the calling program?

A) An object of that class
B) A reference to an object of that class
C) Only the values in the object that the method accessed
D) Nothing, the return type is strictly for documentation in this situation.

Question 15

An object's ________ is simply the data that is stored in the object's fields at any given moment.

A) value
B) assessment
C) record
D) state

Question 16

Which of the following is NOT true about static methods?

A) It is not necessary for an instance of the class to be created to execute the method.
B) They are created by placing the key word static after the access specifier in the method header.
C) They are called from an instance of the class.
D) They are often used to create utility classes that perform operations on data, but have no need to collect and store data.

Question 17

The only limitation that static methods have is:

A) they can refer to only non-static members of the class
B) they can only be called from static members of the class
C) they must be declared as public methods
D) they cannot refer to non-static members of the class

Question 18

If you have defined a class SavingsAccount with a public static method getNumberOfAccounts(), and created a SavingsAccount object referenced by the variable account20, which of the following will call the getNumberOfAccounts()method?

A) getNumberOfAccounts();
B) SavingsAccount.getNumberOfAccounts();
C) getNumberOfAccounts(account20);
D) None of the above, you cannot call a static method.

Question 19

A deep copy of an object:

A) is an assignment of that object to another object
B) is an operation that copies an aggregate object, and all the objects it references
C) is a bogus term, it has no meaning
D) is always a private method

Question 20

If you have defined a class named SavingsAccount with a public static data member named numberOfAccounts, and created a SavingsAccount object referenced by the variable account20, which of the following will assign numberOfAccounts to numAccounts?

A) numAccounts = account20.numAccounts;
B) numAccounts = numberOfAccounts;
C) numAccounts = SavingsAccount.numberOfAccounts;
D) None of the above, you cannot reference a static data member.

Question 21

An instance of a class does not have to exist in order for values to be stored in a class's static fields.

Question 22

The whole-part relationship created by object aggregation is more often called:

A) a has a relationship
B) an inner class relationship
C) an extra class relationship
D) an inside class relationship

Question 23

If you write a toString method to display the contents of an object, object1, for a class, Class1, then the following two statements are equivalent:
System.out.println(object1);
System.out.println(object1.toString());

Question 24

A single copy of a class's static field is shared by all instances of the class.

Question 25

Look at the following declaration: enum Tree { OAK, MAPLE, PINE }
What is the ordinal value of the MAPLE enum constant?

A) 0
B) 1
C) 2
D) 3
E) Tree.MAPLE

Question 26

Enumerated types have this method, which returns the position of an enum constant in the declaration list.

A) toString
B) position
C) ordinal
D) location

Question 27

If you attempt to perform an operation with a null reference variable:

A) the resulting operation will always be zero
B) the results will be unpredictable
C) the program will terminate
D) Java will create an object to reference the variable

Question 28

A declaration for an enumerated type begins with this key word.

A) enumerated
B) enum_type
C) enum
D) ENUM

Question 29

The this key word is the name of a reference variable that is available to all static methods.

Question 30

Assuming the following declaration exists: enum Tree { OAK, MAPLE, PINE }
What will the following code display?
System.out.println(Tree.OAK);

A) Tree.OAK
B) 0
C) 1
D) OAK
E) Nothing. This statement will cause an error.

Question 31

Both instance fields and instance methods are associated with a specific instance of a class, and they cannot be used until an instance of the class is created.

Question 32

When an object is passed as an argument, it is actually a reference to the object that is passed.

Question 33

If the following is from the method section of a UML diagram, which of the following statements is TRUE?
+ add(object2:Stock): Stock

A) This is a private method named add that accepts and returns objects of the Stock class.
B) This is a private method named Stock that adds two objects.
C) This is a public method named add that accepts and returns references to objects in the Stock class.
D) This is a public method named Stock that adds two objects.

Question 34

The JVM periodically performs this process to remove unreferenced objects from memory.

A) memory sweeping
B) garbage collection
C) memory shuffling
D) system restore

Question 35

Look at the following declaration: enum Tree { OAK, MAPLE, PINE }
What is the fully-qualified name of the PINE enum constant?

A) PINE
B) enum.PINE
C) Tree.PINE
D) Tree(PINE)
E) PINE.Tree

Question 36

You cannot use the fully-qualified name of an enum constant for this.

A) a switch expression
B) an argument to a method
C) a case expression
D) all of these

Question 37

What will be returned from a method, if the following is the method header?
Public Rectangle getRectangle()

A) An object of the class Rectangle
B) The address of an object of the class Rectangle
C) The values stored in the data members of the Rectangle object the method changed
D) A graph of a rectangle

Question 38

CRC stands for:

A) Code, Reuse, Constancy
B) Class, Responsibilities, Collaborations
C) Class, Redundancy, Collections
D) Class, Recyclability, Collaborations

Question 39

Assume the class BankAccount has been created, and the following statement correctly creates an instance of the class: BankAccount account = new BankAccount(5000.0);
What is TRUE about the following statement?
System.out.println(account);

A) The method will display unreadable binary data on the screen.
B) A compiler error will occur.
C) The account object's toString method will be implicitly called.
D) A runtime error will occur.

Question 40

When the this variable is used to call a constructor:

A) it must be the first statement in the constructor making the call
B) it must be the last statement in the constructor making the call
C) it can be anywhere in the constructor making the call
D) you cannot use the this variable in a constructor call

Question 41

A class's static methods do not operate on the fields that belong to any instance of the class.

Question 42

An enumerated data type is actually a special type of class.

Question 43

The key word this is the name of a reference variable that an object can use to refer to itself.

Question 44

When an object reference is passed to a method, the method may change the values in the object.

Question 45

You can declare an enumerated data type inside of a method.

Question 46

If you write a toString method for a class, Java will automatically call the method any time you concatenate an object of the class with a string.

Question 47

Enum constants have a toString method.

Question 48

If a class has a method named finalize, it is called automatically just before a data member that has been identified as final of the class is destroyed by the garbage collector.

Question 49

If a class has a method named finalize, it is called automatically just before an instance of the class is destroyed by the garbage collector.

Question 50

The names of the enum constants in an enumerated data type must be enclosed in quotation marks.