JavaWorld Forums: Further confusions with Generics

I am trying to do some mathematical constructions that do not appear to work. I think I am pushing this envelope too far but would like to understand what is wrong: Here is a simple parameterized interface:

public interface Ring<A>
{
public A plus(A a) throws RingException;
public A minus(A a) throws RingException;
public A times(A a) throws RingException;
public A copy() throws RingException;
}

and an attempt to create a generic way to extend any ring by i:

public class Gaussian<A extends Ring<A>> implements Ring<Gaussian<A>>
{
A real;
A imaginary;

/** Creates a new instance of Gaussian */
public Gaussian(A real, A imaginary)
{
this.real = real;
this.imaginary = imaginary;
}

public A getReal() {
return real;
}

public A getImaginary() {
return imaginary;
}

public Gaussian<A> plus(Gaussian<A> b) throws RingException {
return new Gaussian(real.plus(b.getReal()), imaginary.plus(b.getImaginary()));
}

public Gaussian<A> minus(Gaussian<A> b) throws RingException {
A r = real.minus(b.getReal());
A i = imaginary.minus(b.getImaginary());
return new Gaussian(r, i);
}

public Gaussian<A> times(Gaussian b) throws RingException {
A r = (A) real.times((A) b.getReal()).minus((A) imaginary.times((A) b.getImaginary()));
A i = (A) imaginary.times((A) b.getReal().plus((A) real.times((A) b.getImaginary())));
return new Gaussian(r, i);
}

public Gaussian<A> copy() throws RingException {
return new Gaussian((Ring<A>) real.copy(), (Ring<A>) imaginary.copy());
}
}

Gaussian does compile but netbeans 4.0 still complains in the declaration that I have not defined a times correctly according to Ring<A>. Is netbeans off or am I??

Thanks
Ivan
ihandler@igc.org

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