Collections.enumeration() WAS Warning Cleanup Day (original) (raw)

Rémi Forax forax at univ-mlv.fr
Sat Dec 3 04:37:17 PST 2011

I've started to remove warnings from java.util and I'm not able to cleanly retrofit java.util.PropertyPermission because java.util.Collections.enumeration is wrongly typed.

PropertyPermission contains a member class that define a PermissionCollection that store/load only PropertyPermissions. One method of PermissionCollection returns an Enumeration of Permission by calling Collections.enumeration. But Collections.enumeration doesn't use a wildcard.

This is the actual code of Collections.enumeration is public static Enumeration enumeration(final Collection c) { return new Enumeration() { private final Iterator i = c.iterator();

         public boolean hasMoreElements() {
             return i.hasNext();
         }
         public T nextElement() {
             return i.next();
         }
     };
 }

and should be: public static Enumeration enumeration(final Collection<? extends T> c) { final Iterator<? extends T> i = c.iterator(); return new Enumeration() { public boolean hasMoreElements() { return i.hasNext(); } public T nextElement() { return i.next(); } }; }

I believe this change is source and binary compatible because the method is static and a Collection<? extends T> is a super type of Collection.

Rémi

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