Question

My question is close to this one but not quite the same.

I have an inherited (as in, I can’t/won’t change it) array of parameters in my class like so:

public double[] params;

The class utilises these parameters in complex ways, so I would prefer to have human-readable names for each element in the array. In C, you would do something like this

#define MY_READABLE_PARAMETER params[0]

I am also aware that in Java I could create a bunch of constants or an enumerator with attributes. Then, to access a parameter I’d have to type something like this:

params[MY_READABLE_PARAMETER]

This is acceptable but I would really like to omit the array name altogether. Is it possible?

Answer 1

If you have an array of doubles and each array element in a specific position has a definite meaning you should create a class instead.

public class MyParamBlob extends ParentParamBlob
{
    private double myReadableParameter;
    private double anotherParameter;
    private double yetOneMore;

    // getters and setters as appropriate
}

If you need to deal with an existing double[] from “outside” you could have a constructor and/or a method that takes an array as a parameter.

public class MyParamBlob
{
    ...
    public MyParamBlob(double[] values)
    {
        setAll(values);
    }
    // getters and setters as appropriate
    ...
    public void setAll(double[] values)
    {
        myReadableParameter = values[0];
        anotherParameter = values[1];
        // etc.
    }
}

---

Edit – to explain my comment

If the original parent class that this is a subclass of (the reason the double[] exists in the first place) has a getter for the array, that could be overridden in this class, building and returning the array when requested — e.g.

public double[] getParams()
{
    double[] params = new double[4];
    params[0] = myReadableParameter;
    params[1] = anotherParameter;
    // etc.
}

If the array is directly accessible from an instance of the parent class, without a getter, e.g. myArray = parentInstance.params or double d2 = parentInstance.params[2] then (1) that’s a bad design and (2) callers could change the array values out from under you parentInstance.params[1] = 0.0;