how can I implement Comparable more than once?

Question

I\'m upgrading some code to Java 5 and am clearly not understanding something with Generics. I have other classes which implement Comparable once, which I\'ve been able to i

Answer 1

Having multiple implementations of generic interfaces would run into problems when you consider wildcards.

This does not depend upon erasure.

Answer 2

Generics don't exist after bytecode has been compiled.

Restrictions from this: You can't implement / extend two or more interfaces / classes that would be same without the generic parameter and are different with the generic parameter.

What you could do if you really really want type safety is:

interface Foo<T extends Foo<?>> extends Comparable<T>
interface Bar<T extends Bar<?>> extends Comparable<T>
abstract class BarDescription<T extends Bar<?>> implements Bar<T>
class FooBar extends BarDescription<FooBar> implements Foo<FooBar>

Answer 3

I'd write a couple of Comparators and be done with it.