[Fwd: Code review request: 7072353 JNDI libraries do not build with javac -Xlint:all -Werror]

[Neil Richards]

On Wed, 2011-08-03 at 11:03 -0700, Alexandre Boulgakov wrote:
> Please see my responses inline.
> 
> Thanks!
> -Sasha
> 
> On 8/2/2011 9:13 PM, Xuelei Fan wrote:
> > . com/sun/jndi/toolkit/dir/SearchFilter.java
> >   451         for (NamingEnumeration<?>  ve = attr.getAll();
> >   452              ve.hasMore();
> >   453                ) {
> >
> > The update is OK. But the coding style looks uncomfortable. Would you
> > mind change it to use for-each style?
> For-each only works with Iterables. There doesn't seem to be a way to 
> get an Iterable out of an Attribute instance, so the only way to use a 
> for-each here would be to wrap the Enumeration in an ArrayList using 
> Collections.list(). While this might look neater, the contents of the 
> Enumeration would have to be copied over, using time and increasing the 
> memory footprint. Changing Attribute to implement Iterable would require 
> a spec change, and would be beyond the scope of this fix.

Would it  be useful to have a utility object to convert an Enumeration
so it can be used in for-each constructs? - something like:
----
        import java.util.Enumeration;
        import java.util.Iterator;
        
        /**
         * Utility class to transform an Enumeration object such that it can be used in
         * the for-each construct.
         */
        public class IterableEnumerationHolder<E> implements Iterable<E>, Iterator<E> {
            private final Enumeration<E> e;
        
            public IterableEnumerationHolder(final Enumeration<E> e) {
                this.e = e;
            }
        
            @Override
            public Iterator<E> iterator() {
                return this;
            }
        
            @Override
            public boolean hasNext() {
                return e.hasMoreElements();
            }
        
            @Override
            public E next() {
                return e.nextElement();
            }
        
            @Override
            public void remove() {
                throw new UnsupportedOperationException();
            }
        }
----

If it would, perhaps it might be considered for Java 8?

Regards,
Neil

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