枚举hasMoreElements（）返回false

Question

I do this in my code:

            Enumeration liste = attribut.getListe ();
            if (liste != null) {
                while (liste.hasMoreElements ()) {
...

I have one element in my Enumeration but when I inspect liste.hasMoreElements () , why does it return false ?

Answer 1

I would have getListe() always return a collection (empty or otherwise) and only use an Iterator.

eg

for(Entry e: getListe()) {
   // do something with e.
}

Instead of creating an empty list you can use Collections.emptyList() (and other empty collections)

If your Enumeration should have an element but doesn't, it would suggest you have a bug in getListe()

Answer 2

Have you already iterated the enumeration? Ie does getListe() return a new element list?

From the javadoc:

for (Enumeration e = v.elements() ; e.hasMoreElements() ;) {
     System.out.println(e.nextElement());
 }