net.sf.javagimmicks.collections.composite.CompositeEnumeration Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of gimmicks Show documentation

Utility classes, APIs and tools for Java

There is a newer version: 0.99-alpha1

package net.sf.javagimmicks.collections.composite;

import java.util.Enumeration;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;

class CompositeEnumeration implements Enumeration
{
   protected final Iterator> _enumerations;
   
   protected Enumeration _currentEnumeration;
   protected Enumeration _nextEnumeration;
   
   CompositeEnumeration(List> enumerations)
   {
      _enumerations = enumerations.iterator();
      
      findNextEnumeration();
   }
   
   public boolean hasMoreElements()
   {
      if(_currentEnumeration != null && _currentEnumeration.hasMoreElements())
      {
         return true;
      }
      
      findNextEnumeration();
      return _nextEnumeration != null && _nextEnumeration.hasMoreElements();
   }

   public E nextElement()
   {
      if(!hasMoreElements())
      {
         throw new NoSuchElementException();
      }
      
      return moveNext();
   }

   protected void findNextEnumeration()
   {
      if(_nextEnumeration != null)
      {
         return;
      }
      
      while(_enumerations.hasNext())
      {
          _nextEnumeration = _enumerations.next();
          
          if(_nextEnumeration.hasMoreElements())
          {
             break;
          }
      }
   }

   protected E moveNext()
   {
      if(_nextEnumeration != null)
      {
         _currentEnumeration = _nextEnumeration;
         _nextEnumeration = null;
      }
      
      return _currentEnumeration.nextElement();
   }
}