Chapter 9 Quiz

Question 1

Every class in Java, except ________, extends an existing.

Answer 1

Objects

Question 2

Which superclass members are inherited by all subclasses of that superclass?

a. private instance variables and methods.
b. protected instance variables and methods.
c. private constructors.
d. protected constructors.

Answer 2

b. protected instance variables and methods.

Question 3

Using the protected keyword gives a member:

private access
package access
block scope
public access

Answer 3

package access

Question 4

Overriding a method differs from overloading a method because:

Answer 4

Overridden methods have the same signature

Question 5

Superclass methods with this level of access cannot be called from subclasses

Answer 5

Private

Question 6

The default implementation of method clone of Object performs a ________.

Answer 6

shallow copy

Question 7

When a subclass constructor calls its superclass constructor, what happens if the superclass’s constructor does not assign a value to an instance variable?

Answer 7

The program compiles and runs because the instance variables are initialized to their default values

Question 8

Which of the following keywords allows a subclass to access a superclass method even when the subclass has overridden the superclass method?

Answer 8

super

Question 9

Inheritance is also known as the _______

a. knows-a relationship.
b. has-a relationship.
c. uses-a relationship.
d. is-a relationship.

Answer 9

d. Inheritance is known as the is-a relationship.

Question 10

Which of the following is not a superclass/subclass relationship?

a. Employee/Hourly Employee.
b. Vehicle/Car.
c. Sailboat/Tugboat.
d. None of the above.

Answer 10

c. Sailboat/Tugboat (they are both different type of boats, they would both be subclasses of superclass boat.)

Question 11

Which of the following keywords allows a subclass to access a superclass method even when the subclass has overridden the superclass method?

a. base.
b. this.
c. public.
d. super.

Answer 11

d. super (must be called in the default constructor of the subclass)

Question 12

Superclass methods with this level of access cannot be called from subclasses.

a. private.
b. public.
c. protected.
d. package.

Answer 12

a. Private level access

Question 13

private fields of a superclass can be accessed in a subclass

a. by calling private methods declared in the superclass.
b. by calling public or protected methods declared in the superclass.
c. directly.
d. All of the above.

Answer 13

b. By calling public or protected methods in the super class.

Question 14

When overriding a superclass method and calling the superclass version from the subclass method, failure to prefix the superclass method name with the keyword super and a dot (.) in the superclass method call causes ________.

a. a compile-time error.
b. a syntax error.
c. infinite recursion.
d. a runtime error.

Answer 14

c. Infinite Recursion

Question 15

A form of software reuse in which existing classes acquire the member of existing classes and embellish those classes with new capabilities.

Answer 15

Inheritance

Question 16

What members of a super class can be accessed in the superclasses’s declarations and in the subclass declarations.

Answer 16

protected (public variables may be accessed as well but, this is a bad practice)

Question 17

In a _________________ relationship a subclass object can be treated as an object of its superclass.

Answer 17

Inheritance(is-a)

Question 18

In a ________________ relationship a class object has references to objects of other classes as members.

Answer 18

composition(has-a)

Question 19

in single inheritance a class exists in a(n)_________ relationship with its subclasses

Answer 19

is - a

Question 20

A superclasses’s _____________ members can be accessed anywhere the program has a reference to an object of that superclass or to an object of one of its subclasses

Answer 20

public

Question 21

When an object of a subclass is instantiated, a superclass _____________ is called implicitly or explicitly.

Answer 21

constructor

Question 22

Subclass constructors can call superclass constructors via the ________________ keyword.

Answer 22

Super