ShmoopTube

Where Monty Python meets your 10th grade teacher.

Search Thousands of Shmoop Videos


AP Computer Science Videos 110 videos

AP Computer Science 1.1 Classes and Objects
468 Views

AP Computer Science: Classes and Objects Drill 1, Problem 1. Which of the following is a correct {/* Implementation */} for the isInsect method?

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

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

AP Computer Science 1.1 Program Development
404 Views

AP Computer Science 1.1 Program Development. The situation in the video is an example of which of the following?

See All

AP Computer Science 1.3 Classes and Objects 245 Views


Share It!


Description:

AP Computer Science 1.3 Classes and Objects. Which of the following should be declared as a static variable?

Language:
English Language

Transcript

00:01

Sorry And here's your shmoop du jour brought to you

00:05

by boolean Very bills It's True A newbie classes to

00:12

be written that includes the following data members string species

00:16

into hive number boolean is queen and into a number

00:21

of bees assumed that had given b cannot change residences

00:25

or upgrade to queen stats which of the following should

00:28

be declared as a static variable I've number number of

00:32

bees is queen all right What the potential answers Here

00:35

we go we're on the numeral time and okay we're

00:40

being asked which variable or variable should be that flared

00:43

static before we can answer this let's examine what static

00:46

variables are what they do and why they're important Well

00:49

a static variables one whose value will remain constant across

00:52

an entire class of objects If we change the variables

00:55

value for one of the objects it'll reflect across every

00:58

object of that class Well to visualize this let's imagine

01:01

you have a workshop where you build coffee tables and

01:03

you're writing a program to keep track of the tables

01:05

you've made you might have a class called coffee table

01:08

and assign it Some data members such as material type

01:11

table length and numb legs will make numb legs a

01:14

static variables for each table that gets created will need

01:16

to declare the material type length and number of legs

01:19

thiss once made a pine fifty inches long and has

01:22

four legs solid This one's cherry wood very fancy thirty

01:25

inches long and has four legs and this one is

01:28

a metal table thirty inches long and with four legs

01:31

Wait you know what That first one isn't pine it's

01:34

oak We need to go back and change it There

01:37

we go in this example the material type variable is

01:40

not static so when we change that variable for one

01:42

object it doesn't affect the others of that class Numb

01:46

legs however has been declared a static If we change

01:49

that variable for any coffee table object it affects all

01:53

of them on your snacks are all over the floor

01:56

In the case of the bees we've got three variables

01:58

and move to the side which would be more was

01:59

appropriately status we'll hide number is a variable we're using

02:03

to identify which hive each particular be belongs to If

02:06

this were static every bee would belong to the same

02:08

single hive that wouldn't work is a static variable Things

02:12

would get too crowded really quickly Yeah is clean also

02:16

wouldn't work for a couple of reasons First the question

02:18

specified that abi's clean status could not be changed so

02:21

that's a deal breaker but just as importantly even if

02:24

we could change it having that variable static would mean

02:26

everyone would either be a queen or no one would

02:28

be anything at all and that's not gonna work for

02:31

us either So now we're left to look at number

02:33

of bees which is intended to be a counter keeping

02:35

track of exactly that If number of these were static

02:39

and we update this variable for one be it affects

02:42

all of them So that's pretty useful of our possible

02:45

answer b is the only one that fits the bill

02:47

we've identified the on ly number of b should be

02:49

static before we go it's important to remember the distinction

02:52

between static variables and final variables here the sound similar

02:56

but as we learned a static variable is one that

02:59

remains the same across every object in a class If

03:02

it changes for one object it changes for every object

03:05

in that class where's final variables which were not used

03:08

in this question are to find once and never change

03:11

their values you can consider final variables to be set

03:15

in stone like you're no political uncle on facebook Yeah 00:03:19.92 --> [endTime] okay

Related Videos

AP Computer Science 1.2 GridWorld Case Study and APIs
493 Views

AP Computer Science 1.2 GridWorld Case Study and APIs. What is the direction of the actor?

AP Computer Science 1.4 Standard Algorithms
200 Views

AP Computer Science 1.4 Standard Algorithms. How many times will mystery be called for mystery(n) for n > 1?

AP Computer Science 2.3 Classes and Objects
191 Views

AP Computer Science 2.3 Classes and Objects. Which of the following is correct implementation of the Country class?

AP Computer Science 3.4 Inheritance, Abstraction, and Polymorphism
204 Views

AP Computer Science 3.4 Inheritance, Abstraction, and Polymorphism. Which of the following will satisfy the conditional if statement for boo, str,...

AP Computer Science 4.2 Standard Algorithms
191 Views

AP Computer Science 4.2 Standard Algorithms. What kind of algorithm is the following?