Re: Sponsoring getting 5015163 "(str) String merge/join that is the inverse of String.split()" into JDK 7

[Ulf Zibis]

Am 26.10.2009 18:43, Joseph D. Darcy schrieb:
Neal Gafter wrote:
You can hardly add any methods to Object, event static methods, 
without breaking compatibility, because they get added to every the 
overload set if the name is used for methods in existing code.

Indeed, which is why these methods were added in a new class to 
prevent unwanted changes to the meaning of source code.


I don't get the problem. Can anybody help me by an example?
Following code works fine for me:

package java.lang;

public class Object {
   .....

   public static int hashCode(Object obj) {
       return obj.hashCode();
   }

   .....
}

public class MyClass1 {
   private final int value;

   public MyClass1(int value) {
       this.value = value;
   }

   public static int hashCode(MyClass1 obj) {
       return 3 * obj.value;
   }

   public static void main(String... args) {
       MyClass1 c = new MyClass1(99);
       System.out.println(c.hashCode());
       System.out.println(hashCode(c)); // compile error if using 
official version of class Object
   }
}

public class MyClass2 {
   private final int value;

   public MyClass2(int value) {
       this.value = value;
   }

   @Override
   public int hashCode() {
       return value;
   }

   public static void main(String... args) {
       MyClass2 c = new MyClass2(99);
       System.out.println(c.hashCode());
       System.out.println(hashCode(c)); // compile error if using 
official version of class Object
   }
}


-Ulf