Java generic arithmetic

Question

I'm trying to create some Java classes, that should work with either float or double numbers (for simulation purposes I am required to support both). The classes need to do some basic arithmetic and also require use of trigonometric functions (sin, cos, atan2).

I tried to do a generic approach. As Java does not allow primitive types in generics and MyClass<T extends Number> does indeed allow Double and Float, but makes basic arithmetic impossible, I build a wrapper class around Double and Float. But this approach fails, as soon as I need to instantiate a value in one of the generic classes.

Is there any clean way to support both float and double, without duplicating all the code for each type?

Answer 1

Maybe this is what you are looking for?

class MyClass<T extends Number> {
    T add(T t1, T t2) {
        if (t1 instanceof Double) {
            return (T) Double.valueOf((t1.doubleValue() + t2.doubleValue()));
        } else if (t1 instanceof Float) {
            return (T) Float.valueOf(((t1.floatValue() + t2.floatValue())));
        } else if (t1 instanceof Integer) {
            return (T) Integer.valueOf(((t1.intValue() + t2.intValue())));
        }
        // you can add all types or throw an exception
        throw new IllegalArgumentException();
    }

    public static void main(String[] args) {
        MyClass<Double> mc = new MyClass<Double>();
        mc.add(1.0, 1.1);
    }
}