JDK 8 code review request for 8005042 Add Method.isDefault to core reflection (original) (raw)

Peter Levart peter.levart at gmail.com
Wed Dec 19 09:01:19 UTC 2012

On 12/19/2012 01:35 AM, David Holmes wrote:

On 19/12/2012 10:24 AM, Joe Darcy wrote:

On 12/18/2012 04:20 PM, David Holmes wrote:

On 19/12/2012 10:16 AM, Joe Darcy wrote:

On 12/18/2012 04:12 PM, David Holmes wrote:

On 19/12/2012 8:40 AM, Louis Wasserman wrote:

It's not 100% obvious to me whether this refers to a default implementation in an interface, a class which inherits that default implementation and does not override it, or both. Is that worth clarifying in the doc, rather than forcing readers to check the JLS citation?

The issue is where you obtained this Method reference from: - from the Interface? then it is a default method - from a class implementing the interface but not redefining the method? then it is a default method Actually, that is now how HotSpot represents this case in core reflection at the moment. HotSpot uses a new method object to represent the default method woven into an implementing class. now -> not ?? Correct. It may be a new Method object but getDeclaringClass() should give the interface class NOT the concrete class. That is currently the case for abstract interface methods. I hope it is the same for default methods! It is not at the moment, which is a bit surprising. Very surprising! I'd call that a major bug.

Not only default methods, also abstract interface methods show-up in the implementing class's declared methods. For example the following test:

public class DefaultMethodsTest { public interface I { void i(); default void d() { } }

 public abstract static class S {
     public abstract void a();
     public void s() { }
 }

 public abstract static class C extends S implements I {
     public void c() { }
 }

 public static void main(String[] args) {
     for (Method m : C.class.getDeclaredMethods())
         System.out.println(m.getName());
 }

}

prints:

c i d

Regards, Peter

David -----

-Joe

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