#Relationship between variables and their assigned objects:

1 messages · Page 1 of 1 (latest)

heady glacierBOT
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<@&987246399047479336> please have a look, thanks.

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versed mirage
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In short, I don't understand the significance of distinguishing an object from its class of variable

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e.g.,
r2.getCurrentRow() seems to get the current row of the RookS object that r2 refers to

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but r2.currentRow accesses the currentRow attribute of its PieceS variable?

signal kelp
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also your rooks is returning its local field, not its super

versed mirage
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I didn't write this btw I just don't understand why it would do this based on my understanding of java lol

versed mirage
signal kelp
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since u got a local field there, it will return that, not the super

versed mirage
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right ok

and calling r2.currentRow accesses the super attribute instead?

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(this is r2 btw: PieceS r2 = new RookS(8,3))

signal kelp
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alter that code and see what it prints

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( also its kinda weird code aswell , school example ? )

versed mirage
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when r2.getCurrentRow() is called, it makes sense that it would access the RookS instance variable
but why should rn.currentRow access that of its superclass? I assume that this has something to do with the fact that r2 is a PieceS variable with a RookS object assigned

versed mirage
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it's meant to demonstrate shadowing

versed mirage
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i have theories is all

signal kelp
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rn.curentRow has a local variable aswell with that name

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public class RookS extends PieceS {
    public int currentRow;
    public int currentColumn;
    public RookS(int currentRow, int currentColumn) {
        super(currentRow, currentColumn);
    }
    public int getCurrentRow() {
        return this.currentRow;
    }
}
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is what is happening

versed mirage
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so when r2.currentRow is processed

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what is interpreted?
it seems like java thinks I'm referring to the currentRow in the superclass

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even though like you say, r2 has a local variable with the same name

signal kelp
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print out the object's actual class

versed mirage
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true

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is there a standard method for doing that

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i don't think i've needed to do that as of yet

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only used instanceof

signal kelp
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at the moment don't overthink on it, this whole example is weird

versed mirage
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added this line

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System.out.println(r2.getClass().toString());

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it says

signal kelp
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rooks shoudlnt even have the 2 fields in a real example

versed mirage
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class RookS

versed mirage
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but I have an exam tomorrow for this subject haha
and I bet they're gonna try and trip me up on the particulars of the object-variable relationship

signal kelp
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hoping u did the basic examples, did u happen to see the dog and cat example ?

versed mirage
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"the" dog and cat example?

signal kelp
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dog/cat extends animal

versed mirage
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yeah, I recall

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i'm familiar with inheritance and the general rules

it's just this one example

signal kelp
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right, in there is usually a method called makeSound

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so if u place String sound = "" in animal; String sound ="woof" in dog, and String sound="im pure evil" in cat; then your doing the same thing as in your example

versed mirage
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right that makes sense

do you know anything about the implications of this though?

// this
RookS r1 = new RookS(4, 3);

// versus this
PieceS r2 = new RookS(4, 3);
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are there any general rules about how to interpret this sort of thing when the variable type differs from the obj type

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I suppose accessing the attribute directly takes the one from the superclass or sth

signal kelp
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might explain your last example a bit

versed mirage
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nice cool

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thanks fa285634

signal kelp
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maybe a bad explanation on that code is -> i know your a pieceS, but i dont care what extended things u got added. Your going to do stuff from pieceS anyway

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or i know your a car, even if your hybrid, fossile or solar. You'r going to start()