Question

I’m having a hard time finding what I need, and figuring out how to ask for it so please consider this:

public class Environment {
    int x = 0;
    int y = 0;
    Operations op = new Operations();

    public Environment(){
        Operations.changeSuper();
    }
}

and:

public class Operations extends Environment {
    public void changeSuper(){
        x++;
        y--;
    }
}

This is a simple representation of what I have attempted already. However I dont think that initializing Operations in Environment correct, as it causes the constructor to loop. But if I dont, then I get null pointer when I attempt to call changeSuper().

Is this the correct way to use extends? Whould there be a better way to abstract the methods from the class file.

Long story short, I want to move methods out of a class file, but still allow them to affect it’s local variables

Answer 1

Environment isn’t an Operations.. so no.
Sounds like you need composition. And you should make your class Operation not Operations.

So have something like so:

public class Environment {
    int x = 0;
    int y = 0;
    Operation op ;

    public Environment(){
         op=new Operation(this);

    }

    public void changeEnvironment() {}
    public void incrementX(){}
    public void incrementY() {}
}

and:

public class Operation   {
    Environment e;
    public Operation(Environment e){
        this.e = e;
        e.incrementX();
        e.decrementY();
    }
    public void changeEnvironment()
    {   
       e.changeEnvironment() ;
    }
}

If the changes is done only in Environment, then it makes maintaining easier, also preserving encapsulation.