Re: How convert Iterator into Enumeration

Eric Sosman <esosman@comcast-dot-net.invalid>
Wed, 28 Nov 2012 13:22:34 -0500
On 11/28/2012 6:55 AM, Jan Burse wrote:

Dear All,

Is there a fast way to have an Enumeration from a HashMap?

I am trying to reimplement the HttpServletRequest interface,
and I am trying to use a HashMap for parameters and attributes.
I guess this is valid when my web application doesn't use
a HttpServletRequest concurrently, right? Or might the web
server populate it concurrently?

Now I am stuck here:

      * <p>Retrieve the parameter names.</p>
      * @return The names.
     public Enumeration<String> getParameterNames() {
         return parametermap.keys();

public Enumeration<String> getParameterNames() {
        return new Enumeration<String>() {
            private final Iterator<String> iter =
            public boolean hasMoreElements() {
                return iter.hasNext();
            public String nextElement() {

If you do this sort of thing a lot write yourself a utility
class implementing Enumeration<T>, with a constructor that
takes an Iterator<T>. A companion class wrapping an Iterator<T>
around an Enumeration<T> is equally easy to write, and might
also be handy. (I'm a little surprised that Snoracle doesn't
provide such wrappers -- or maybe they do, but under names
that have escaped my notice.)

Eric Sosman

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