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AP Computer Science A Videos 108 videos

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AP Computer Science 1.1 Inheritance, Abstraction, and Polymorphism 203 Views


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Description:

AP Computer Science 1.1 Inheritance, Abstraction, and Polymorphism. Which of the following are correct?

Language:
English Language

Transcript

00:00

Thank you We sneak and here's your smoke Do sure

00:05

try to sit up straight Just imagine you're a glam

00:08

metal bands hair Consider the following class hierarchy Upward arrows

00:12

indicate an inheritance relationship which of the following are correct

00:17

And here the potential answers Yeah All right as the

00:22

problem states up arrows indicated inheritance relationship and we already

00:27

know that inheritance is just a big fancy word for

00:30

is a relationship No fast song is a song slow

00:34

song is a song too and we can go step

00:37

further and say power ballad is a slow song which

00:42

is a song Well we could extend this even further

00:44

by saying november rain is a power ballad november rain

00:48

than inherits any and all of the fields methods and

00:51

nested classes from power ballad which inherits from slow song

00:56

which inherits from song for exam song would contain members

01:00

that are relevant all songs and every subclass of song

01:03

things like are this name instruments song blank and so

01:07

on things that every song will have Well november rain

01:11

would be extremely specific like emotional axl rose vocal which

01:16

is something out every single half aside from simply knowing

01:19

their relationship between classes It's also important to know how

01:22

to properly declare and create a variable setting it all

01:27

up typically goes like this class variable named equals new

01:32

glass for supplies Yeah right left side of the equation

01:36

declares a variable to refer to An object song a

01:39

for example lets the compiler know that you're going to

01:42

use a to refer to data of the variety song

01:45

but that object doesn't actually yet exist On the other

01:49

side of the equation we get down and dirty and

01:51

actually a sign an object to that variable A new

01:54

power ballad for example would be created with song a

01:57

equals new power valid All right the question is asking

02:00

us which of these three option for declaring in creating

02:03

variables are correct starting with option one song a equals

02:07

new power balance and that's what we just did a

02:09

second ago and it works too and song be equals

02:12

New slow jam Yeah perfectly good way of creating a

02:15

slow jam Another good way would involve candles rose petals

02:19

and a saxophone solo But this is a little quicker

02:22

option One is good Option two is a little weird

02:25

It has as creating a slow song and power valid

02:28

and having them equal new song and slow song objects

02:32

but that's just not gonna fly the left side of

02:35

the equation declares variables name and its class and the

02:38

right side actually creates the object Option two is trying

02:42

to declare a variable of the type that's a subclass

02:44

of the actual object or creating that's like declaring that

02:48

you're going to be dracula for halloween But he actually

02:50

dress up some generic monster The option to option three

02:55

works like option one declaring variables and b to be

02:57

songs and then creates new fast song and slow song

03:01

objects So yeah three work with options One of three

03:04

working and to being wrong That makes the our answer

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