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Thread: Access and set variable in parent class through child

  1. #1
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    Default Access and set variable in parent class through child

    Hi,

    I have 3 classes, A, B, and C.

    B extends A, and C extends B. Each class has a protected variable named x. Class A has a method to set x, and one to retrieve x, which I understand are inherited by both B and C.

    What I'm trying to do is also have a method in C that can access and set the x in A. So far, everything I've tried will only make changes to the x in C.

    class A {
    protected int x = 0;

    A() {x = 0;}

    void setX(int value) {x = value;}
    void getX() {System.out.println(x);}
    }

    class B extends A {
    protected int x = 0;

    B() {x = 0;}
    }

    class C extends B {
    protected int x = 0;

    C() {x = 0;}

    void setAfromC(int value) {} // I imagine this is what I'm missing??
    void getAfromC() {}
    }

    public class Test {
    public static void main( String[] args ) {
    A a = new A();
    B b = new B();
    C c = new C();

    a.setX(1);
    b.setX(2);
    c.setX(3);

    a.getX();
    b.getX();
    c.getX();

    c.setAfromC(2);
    c.getAfromC(); //This should output 2,
    c.getX(); //while this should still output 3!
    }
    }

    I've tried using "super.", but I learned that it only lets me use A's methods to apply them to C's variables.

    I would really appreciate a hint as to how to do this!


  2. #2
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    Default Re: Access and set variable in parent class through child

    Sorry if I haven't understood what you wanted, but does..
        void setAfromC(int value) {
            setX(value);
        } // I imagine this is what I'm missing??
        void getAfromC() {
            getX();
        }

    ..do what you needed?

    (Just a shot in the dark sorry )
    Please use [highlight=Java]//code goes here...[/highlight] tags when posting your code

  3. #3
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    Default Re: Access and set variable in parent class through child

    Quote Originally Posted by newbie View Post
    Sorry if I haven't understood what you wanted, but does..
        void setAfromC(int value) {
            setX(value);
        } // I imagine this is what I'm missing??
        void getAfromC() {
            getX();
        }

    ..do what you needed?

    (Just a shot in the dark sorry )

    Thanks for trying to help out!

    The problem is that I'm trying to change the x in A through a method in C. Doing what you suggested only changes the x in C, which I'm actually trying to leave unchanged!

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    Administrator copeg's Avatar
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    Default Re: Access and set variable in parent class through child

    Answered Here. Please read this for why cross-posting like this is frowned upon

  5. #5
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    Default Re: Access and set variable in parent class through child

    Quote Originally Posted by copeg View Post
    Answered Here. Please read this for why cross-posting like this is frowned upon
    Ah, good ol' copeg and your royal-blue linking. How would you survive if link tags were never invented?
    NOTE TO NEW PEOPLE LOOKING FOR HELP ON FORUM:

    When asking for help, please follow these guidelines to receive better and more prompt help:
    1. Put your code in Java Tags. To do this, put [highlight=java] before your code and [/highlight] after your code.
    2. Give full details of errors and provide us with as much information about the situation as possible.
    3. Give us an example of what the output should look like when done correctly.

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