AP Computer Science 1.3 Classes and Objects

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

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Transcript

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or upgrade to queen stats which of the following should

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

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bees is queen all right What the potential answers Here

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

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being asked which variable or variable should be that flared

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

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

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a static variables one whose value will remain constant across

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an entire class of objects If we change the variables

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

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

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you have a workshop where you build coffee tables and

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

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

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and assign it Some data members such as material type

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table length and numb legs will make numb legs a

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static variables for each table that gets created will need

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to declare the material type length and number of legs

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thiss once made a pine fifty inches long and has

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

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inches long and has four legs and this one is

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a metal table thirty inches long and with four legs

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

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oak We need to go back and change it There

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we go in this example the material type variable is

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not static so when we change that variable for one

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

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legs however has been declared a static If we change

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that variable for any coffee table object it affects all

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of them on your snacks are all over the floor

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

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and move to the side which would be more was

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

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to identify which hive each particular be belongs to If

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this were static every bee would belong to the same

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

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would get too crowded really quickly Yeah is clean also

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

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

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

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we could change it having that variable static would mean

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everyone would either be a queen or no one would

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

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

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of bees which is intended to be a counter keeping

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track of exactly that If number of these were static

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and we update this variable for one be it affects

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

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answer b is the only one that fits the bill

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

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

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between static variables and final variables here the sound similar

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but as we learned a static variable is one that

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remains the same across every object in a class If

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it changes for one object it changes for every object

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

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in this question are to find once and never change

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their values you can consider final variables to be set

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