How to implement unit converter in Java

How can I implement a unit converter in Java??? I'm thinking about an abstract base class:

public abstract class Unit {
    ...
    public void convertTo(Unit unit);
}

Then let each class, such as meter kilometer inch centrimeter millimeter... Derive from this basic unit class All length units are in a named com unitconverter. Distance package, then a package, com unitconverter. Energy, used for energy, etc So is this the best way to implement a unit converter? Or is there a better or simpler way?

Solution

There is considerable work on this, including JSR 108 (withdrawal) and jsr-275 (rejection) See the jsscience and unitsofmeasure implementations of the latter