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AP Computer Science A Videos 108 videos

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AP Computer Science 1.2 Program Development 293 Views


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Description:

AP Computer Science 1.2 Program Development. Which of the following is correct?

Language:
English Language

Transcript

00:00

Thank you We sneak and here's your shmoop du jour

00:05

brought to you by super class is not to be

00:07

confused with supper classes But if you're already wearing your

00:11

lobster bin well leave it all right This question is

00:15

based on the following class hierarchy diagram this one Note

00:19

that in open air own denotes an inheritance relationship and

00:22

a closed aero denotes a composition relationship though which of

00:26

the following is correct And here the potential answers has

00:32

there Mike all right well here we have a question

00:35

about a pretty basic class hierarchy structure whenever something like

00:39

this crops up It's important to remember that there are

00:41

two kinds of relationships Glasses can have inheritance and composition

00:47

Except those two words are needlessly convoluted and actually pretty

00:52

vague when you think about it So they often get

00:55

referred to as isa and has a relationship when two

01:00

classes related one either is the other or has the

01:03

other okay Subtle but important Consider this The class limb

01:08

is related to the classes of arm and leg An

01:12

army is a limb just a more specific kind of

01:15

limb and sore legs A foot is not a leg

01:18

But they're still related instead of leg has a foot

01:22

got it Give yourself a hand We've got a leg

01:25

up and are ready to go toe to toe with

01:27

questions So here we have our hierarchy of classes and

01:31

we can see that north american country is a country

01:35

is seeing yousa as our european country and asian country

01:39

East asian country is an asian country too They're our

01:44

inheritance relationships and our denoted by the downward open arrows

01:48

these things state is not a north american country However

01:53

this is a has a situation where north american country

01:57

has a state north american country can also have a

02:02

territory or province thes composition relationships air denoted by upward

02:06

close aargh and we're being asked which of the following

02:10

is correct so let's look alright option a says north

02:13

american country is a super class of state not quite

02:16

north american country has a state so it's a composition

02:20

relationship rather than an inheritance relationship No super classes around

02:24

here option b r v says there is a has

02:28

a relationship between asian country and east asian country We'll

02:32

not it off east asian country is an asian country

02:36

is this one out of here Option c there is

02:38

a has a relationship between north american country and province

02:42

Yes the diagram pretty clearly shows that's the case upward

02:48

arrow and everything Yep let's Check the others though right

02:50

option d says state is a subclass of country well

02:54

no countries way up here in states way down here

02:58

So north american country has a state but it's not

03:01

the same thing He makes almost the same error reaching

03:04

all the way across The diagram in claiming country has

03:07

a territory well no not at all North american country

03:10

has a territory but country doesn't That means sea is

03:14

definitely our answered North american country has province and ice

03:18

hockey and mounties and ryan gosling's from there and polar

03:21

bears and kids in the hall and the roots and

03:24

half a niagara falls And that life is a highway 00:03:27.27 --> [endTime] song

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