Why aren't Enumerations Iterable?

java enumeration iterable
SCdF picture SCdF · Aug 26, 2008 · Viewed 20.3k times · Source

In Java 5 and above you have the foreach loop, which works magically on anything that implements Iterable:

for (Object o : list) {
  doStuff(o);
}

However, Enumerable still does not implement Iterable, meaning that to iterate over an Enumeration you must do the following:

for(; e.hasMoreElements() ;) {
  doStuff(e.nextElement());
}

Does anyone know if there is a reason why Enumeration still does not implement Iterable?

Edit: As a clarification, I'm not talking about the language concept of an enum, I'm talking a Java-specific class in the Java API called 'Enumeration'.

Answer

Tom Hawtin - tackline picture Tom Hawtin - tackline · Sep 5, 2008

As an easy and clean way of using an Enumeration with the enhanced for loop, convert to an ArrayList with java.util.Collections.list.

for (TableColumn col : Collections.list(columnModel.getColumns()) {

(javax.swing.table.TableColumnModel.getColumns returns Enumeration.)

Note, this may be very slightly less efficient.

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