University Of Arizona: Ece 373: Inheritance And Interfaces

Front 1

inheritance creates what kind of relationship?

Back 1

is-a

Front 2

a subclass has...

Back 2

-All characteristics of superclass

-adds it own/modifies characteristics

Front 3

which keyword is used on the class header to define a subclass?

Back 3

extends

Front 4

Members of the superclass that are marked private...

Back 4

– are not inherited by the subclass
– exist in memory when the object of the subclass is created
– may only be accessed from the subclass by public methods of the superclass

Front 5

Members of the superclass that are marked public...

Back 5

– are inherited by the subclass
– may be directly accessed from the subclass

Front 6

Constructors are not...

Back 6

inherited.

Front 7

The super keyword allows what?

Back 7

the superclass constructor to be explicitly called.

Front 8

Calls to the superclass constructor must be what?

Back 8

the first java statement in the subclass constructors.

Front 9

Can methods in subclasses have the same signature as methods in the super class?

Back 9

yes; this is call method overriding.

Front 10

how can an over ridden superclass method be called?

Back 10

with the the super keyword.

i.e. super.setScore(rawScore * percentage);

Front 11

How can a superclass prevent a method from being over ridden?

Back 11

the final keyword.

i.e. public final void message()

Front 12

Protected members of a class...

Back 12

-may be accessed by methods in a subclass

-may be accessed by methods in the same package as the class

Front 13

be default the access modifier allows...

Back 13

Access to all classes in the same package.

Front 14

An abstract class...

Back 14

-Cannot be instantiated

-serves as a super class

-place abstract keyword in class definition

i.e. public abstract class ClassName

Front 15

an abstract method...

Back 15

- appears in the superclass

-expects to be over ridden in the subclass

-has only a header and no body

-ensures that every concrete subclass implements the method

i.e. public abstract void setValue(int value)

Front 16

If a class has an abstract method it is?

Back 16

an abstract class and must be declared so.

Front 17

A reference variable is polymorphic because?

Back 17

It can reference objects of types different from its own, as long as those types are subclasses of it's type.

Front 18

dynamic/late binding occurs when?

Back 18

A variable contains a polymorphic reference.

Front 19

dynamic/late binding is?

Back 19

When the Java virtual machine determines at runtime which method to call, depending on the type of object that the variable references.

-Object type (not reference type) determines which method is called

Front 20

Can a superclass object ne assigned to a subclass reference variable?

Back 20

No

Front 21

An interface...

Back 21

-Cannot be instantiated

-all methods listed in interface must be implemented if a class implements the interface.

-Specifies behavior for other classes

-methods are public by default and have no bodies

Front 22

How many interfaces can be implemented by a class?

Back 22

Any number

i.e. public class MyClass implements

Interface1,
Interface2,
Interface3

Front 23

interface format?

Back 23

public interface InterfaceName
{
(Method headers...)
}

Front 24

How is an interface implemented?

Back 24

uses implements keyword

i.e.

public class FinalExam3 extends GradedActivity implements
Relatable
{ ….}

Front 25

In UML diagrams implementation of an interface is shown via what?

Back 25

dashed line

Front 26

Fields in an interface are?

Back 26

-Final and static

-Must be initialized

-any class implementing interface has access to these variables

Front 27

A reference variable of an interface type...

Back 27

-allows any object implementing the interface has access to variable.

Front 28

When a class implements an interface an inheritance relationship known as what is established?

Back 28

interface inheritance

Front 29

When a reference to an object is a interface variable...

Back 29

-Only those methods declared in the interface are available.

-Explicit type casting is required to access the other methods