Getting duplicate fields when setting from Concrete class

I need to define constant values in each ConcreteClass that extends AbstractClass. For some reason object ends up having duplicate fields, one set of fields is equal to zeros, next one has proper values.

SomeInterface

public interface SomeInterface{
    double calculate();
} 

AbstractClass

public abstract class AbstractClass implements SomeInterface{
       double x, y;

       public double calculate(){
            return x*y;
       }
    }

ConcreteClass

public class ConcreteClass extends AbstractClass{

    final double x = 1.1;
    public setY(double y){
        this.y = y;
    }

} 

I need my concrete class to store constant value final double x = 1.1; while inheriting the calculate() method implementation from abstract class.

You have declared x twice, so you get two x variables; one masks the other. It's doing what you told it to.

To have the concrete class set a value, put the setting of it in a (or all) constructor(s) of the ConcreteClass. Don't declare it again.

I don't know a way that you can declare it final and still alter it in a subclass.