On Nov 20, 2013, at 4:31 PM, Remi Forax <[email protected]> wrote:
> But while you can declare a default hashCode and equals, it will not work
> because the implementation of Object.hashCode and Object.equals will always
> be preferred to the default methods by the VM, this is how default methods
> are specified. Not something I'm very proud.
Next question: What's the best practice for declaring reusable code for
exactly those restricted methods (hashCode/equals, toString)? Because of the
irregularity with Object, the opt-in isn't by default, but there should still
be a convention for supplying the code as a "would-be default method".
Maybe one of:
interface KoolReusablePair {
default boolean defaultEquals(Object x) { ... }
static int hashCode(KoolReusablePair self) { ... }
...
}
class KoolImpl implements KoolReusablePair {
@Override //manual opt-in:
public boolean equals(Object x) { return
KoolReusablePair.super.defaultEquals(x); }
@Override //manual opt-in:
public int hashCode() { return KoolReusablePair.hashCode(this); }
...
}
— John
