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Java 8 question about default and static methods in interfaces

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  Java 8 question about default and static methods in interfaces Wayne <nospam@all.invalid> - 2014-01-26 04:55 -0500
    Re: Java 8 question about default and static methods in interfaces Arne Vajhøj <arne@vajhoej.dk> - 2014-01-26 07:56 -0500
      Re: Java 8 question about default and static methods in interfaces Arne Vajhøj <arne@vajhoej.dk> - 2014-01-26 13:12 -0500
        Re: Java 8 question about default and static methods in interfaces Wayne <nospam@all.invalid> - 2014-01-26 20:37 -0500

#27398 — Java 8 question about default and static methods in interfaces

Consider the following Java 8 interfaces:

  public interface Foo {
    default void method () {
      System.out.println("Foo.method");
    }
  }
  public interface Bar extends Foo {
    default void method () {
      System.out.println("Bar.method");
    }
  }

The question is, can Foo.method be used from Bar.method?
In other words, is the following version of Bar legal?

  public interface Bar extends Foo {
    default void method () {
      super.method();
      System.out.println("Bar.method");
    }
  }

I didn't see a reference in the docs I used, if static
methods can be redefined as well.  Does anyone know?

I'd appreciate a link I could use for a better reference
than the Oracle Java Tutorial.

-- 
Wayne

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#27399

On 1/26/2014 4:55 AM, Wayne wrote:
>    public interface Foo {
>      default void method () {
>        System.out.println("Foo.method");
>      }
>    }
>    public interface Bar extends Foo {
>      default void method () {
>        System.out.println("Bar.method");
>      }
>    }
>
> The question is, can Foo.method be used from Bar.method?
> In other words, is the following version of Bar legal?
>
>    public interface Bar extends Foo {
>      default void method () {
>        super.method();
>        System.out.println("Bar.method");
>      }
>    }

Well - the following compiles and run with Java 8 EA something:

public class DefMet {
     public static void main(String[] args) {
         Bar o = new C();
         o.method();
     }
}

class C implements Bar {
}

interface Foo {
     default void method () {
         System.out.println("Foo.method");
     }
}

interface Bar extends Foo {
     default void method () {
         Foo.super.method();
         System.out.println("Bar.method");
     }
}

Note the use of Foo.super instead of just super.

Arne

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#27400

On 1/26/2014 7:56 AM, Arne Vajhøj wrote:
> On 1/26/2014 4:55 AM, Wayne wrote:
>>    public interface Foo {
>>      default void method () {
>>        System.out.println("Foo.method");
>>      }
>>    }
>>    public interface Bar extends Foo {
>>      default void method () {
>>        System.out.println("Bar.method");
>>      }
>>    }
>>
>> The question is, can Foo.method be used from Bar.method?
>> In other words, is the following version of Bar legal?
>>
>>    public interface Bar extends Foo {
>>      default void method () {
>>        super.method();
>>        System.out.println("Bar.method");
>>      }
>>    }
>
> Well - the following compiles and run with Java 8 EA something:
>
> public class DefMet {
>      public static void main(String[] args) {
>          Bar o = new C();
>          o.method();
>      }
> }
>
> class C implements Bar {
> }
>
> interface Foo {
>      default void method () {
>          System.out.println("Foo.method");
>      }
> }
>
> interface Bar extends Foo {
>      default void method () {
>          Foo.super.method();
>          System.out.println("Bar.method");
>      }
> }
>
> Note the use of Foo.super instead of just super.

Syntax must be intended for:

public class DefMet2 {
     public static void main(String[] args) {
         Bar o = new C();
         o.method();
     }
}

class C implements Foo, Bar {
     public void method() {
         Foo.super.method();
         Bar.super.method();
         System.out.println("C.method");
     }
}

interface Foo {
     default void method () {
         System.out.println("Foo.method");
     }
}

interface Bar {
     default void method () {
         System.out.println("Bar.method");
     }
}

Arne

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#27404

On 1/26/2014 1:12 PM, Arne Vajhøj wrote:
> On 1/26/2014 7:56 AM, Arne Vajhøj wrote:
>> On 1/26/2014 4:55 AM, Wayne wrote:
>>>    public interface Foo {
>>>      default void method () {
>>>        System.out.println("Foo.method");
>>>      }
>>>    }
>>>    public interface Bar extends Foo {
>>>      default void method () {
>>>        System.out.println("Bar.method");
>>>      }
>>>    }
>>>
>>> The question is, can Foo.method be used from Bar.method?
>>> In other words, is the following version of Bar legal?
>>>
>>>    public interface Bar extends Foo {
>>>      default void method () {
>>>        super.method();
>>>        System.out.println("Bar.method");
>>>      }
>>>    }
>>
>> Well - the following compiles and run with Java 8 EA something:
>>
>> public class DefMet {
>>      public static void main(String[] args) {
>>          Bar o = new C();
>>          o.method();
>>      }
>> }
>>
>> class C implements Bar {
>> }
>>
>> interface Foo {
>>      default void method () {
>>          System.out.println("Foo.method");
>>      }
>> }
>>
>> interface Bar extends Foo {
>>      default void method () {
>>          Foo.super.method();
>>          System.out.println("Bar.method");
>>      }
>> }
>>
>> Note the use of Foo.super instead of just super.
> 
> Syntax must be intended for:
> 
> public class DefMet2 {
>     public static void main(String[] args) {
>         Bar o = new C();
>         o.method();
>     }
> }
> 
> class C implements Foo, Bar {
>     public void method() {
>         Foo.super.method();
>         Bar.super.method();
>         System.out.println("C.method");
>     }
> }
> 
> interface Foo {
>     default void method () {
>         System.out.println("Foo.method");
>     }
> }
> 
> interface Bar {
>     default void method () {
>         System.out.println("Bar.method");
>     }
> }
> 
> Arne
> 
> 

Thanks!

-- 
Wayne

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