copy from one enumeration into another!!

[Ravi Kumar Ravuru]

Hello Folks,
Can i copy the contents of one enumeration into another enumeration.Please help me out.
Thanks in Advance.
Ravi

[Anonymous]

An Enumeration is an (old) interface. Nothing in that interfacce allows you to store new elements in that enumeration. You could of course catenate two (or more) enumerations as follows:

public class EnumCatenator implements Enumeration {
   private boolean first= true;
   private Enumeration a;
   private Enumeration b;
   public EnumCatenator(Enumeration a, Enumeration b) {
      this.a= a;
      this.b= b;
   }
   public boolean hasMoreElements() {
      if (first && a.hasMoreElements())
         return true;
      first= false;
      
      return b.hasMoreElements();
   }
   public Object getNextElement() {
      return first?a.getNextElement()
                  :b.getNextElement();
   }
}

kind regards

[Ravi Kumar Ravuru]

Hello Jos Horsmeier,
Thanks for ur reply.But i need to copy the elements of one enumeration to another enumeration. Is it possible.
Ravi

[Anonymous]

No, it's not possible, like I wrote in my previous reply: an enumeration is simply an interface, nobody knows whether or not the implementing class is able to 'store' additional objects in it. All you can do is iterate over the two enumerations and store the retrieved objects in, say, an ArrayList or Vector or similar.
For the sake of the argument, assume that the 'other' enumeration, where you want to store additional values, is implemented as:

public class Counter implements Enumeration {
   private int i= 0;
   public boolean hasMoreElements() {
      return i < 42;
   }
   public Object getNextElement() {
      return new Integer(i++);
   }
}

This silly class makes up a perfectly valid Enumeration, but you sure cannot store any elements in it ...
kind regards

[Bear Bibeault]

What you can do is to copy each element of the original enumeration to a Vector, and then get an enumeration of the vectored elements via the elements() method.
hth,
bear