Re: why is multiple inheritance not implemented in java?
Eric Sosman <esosman@ieee-dot-org.invalid> writes:
interface Ownable {
/** Return true iff the Ownable belongs to me. */
boolean mine();
}
interface Diggable {
/** Send diggers into the mine to dig up the Diggable. */
void mine();
}
class Diamond implements Ownable, Diggable {
// ???
}
(I'm not a language theorist and my understanding of the "diamond
problem" may well be imperfect, but to my inexpert eye this looks
a lot like it. Or maybe like some related problem?)
It is *a* diamond problem (cute too!), but not the diamond problem.
Try instead
abstract class AA {
public int foo();
}
class AB extends AA {
public int foo() { return 42; }
}
class BA extends AA {
public int foo() { return 37; }
}
class BB extends AB,BA /*multiple inheritance, if it existsed */ {
}
{
AA a = new BB();
System.out.println(a.foo());
}
The class inheritance diagram forms a diamond, with the BB class
inheriting two implementations of the *same* method.
/L
--
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