Sorry, I misunderstood, I missed that the methods weren't already defined in ObservableMap, so no existing signature is changed.

--John

On 30/05/2022 09:39, Tom Schindl wrote:
Hi,

Well the binary compat IMHO is not a problem. If your subtype overwrites the return type of a method the compiler will inserts a bridge method:

Take this example

package bla;

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

public class Test {
    public interface IB {
        public Collection<String> get();
    }

    public interface I extends IB {
        public List<String> get();
    }

    public class C implements I {
        public ArrayList<String> get() {
            return new ArrayList<String>();
        }
    }
}

if you look at C with javap you'll notice

Compiled from "Test.java"
public class bla.Test$C implements bla.Test$I {
  final bla.Test this$0;
  public bla.Test$C(bla.Test);
  public java.util.ArrayList<java.lang.String> get();
  public java.util.Collection get();
  public java.util.List get();
}


The problem is more that if someone directly implemented ObservableMap him/her self that it won't compile anymore. So it is a source incompatible change.

Tom

Am 30.05.22 um 08:58 schrieb John Hendrikx:
It's not binary compatible, as changing the return type results in a new method that compiled code won't be able to find.

See also "change result type (including void)" here: https://wiki.eclipse.org/Evolving_Java-based_APIs_2#Evolving_API_interfaces_-_API_methods

--John

On 30/05/2022 03:22, Nir Lisker wrote:
Hi,

Picking up an old issue, JDK-8091393 [1], I went ahead and looked at the
work needed to implement it.

keySet() and entrySet() can both be made to return ObservableSet rather
easily. values() will probably require an ObservableCollection<E> type.

Before discussing these details, my question is: is it backwards compatible to require that these  methods now return a more refined type? I think that
it will break implementations of ObservableMap out in the wild if it
overrides these methods in Map. What is the assessment here?

https://bugs.openjdk.java.net/browse/JDK-8091393

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