net.sf.javagimmicks.collections.event.AbstractEventSet 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.event;

import java.util.Iterator;
import java.util.Set;

import net.sf.javagimmicks.collections.decorators.AbstractUnmodifiableSetDecorator;

/**
 * A base {@link Set} wrapper that reports changes to internal callback methods
 * - these must be overwritten by concrete implementations in order to react in
 * any way to the changes.
 * 
 * Methods that must be overwritten:
 * 

 * {@link #fireElementAdded(Object)}
 * {@link #fireElementReadded(Object)}
 * {@link #fireElementRemoved(Object)}
 * 
 */
public abstract class AbstractEventSet extends AbstractUnmodifiableSetDecorator
{
   private static final long serialVersionUID = -7712383972215104949L;

   /**
    * Wraps a new instance around a given {@link Set}
    * 
    * @param decorated
    *           the {@link Set} to wrap
    */
   public AbstractEventSet(final Set decorated)
   {
      super(decorated);
   }

   @Override
   public boolean add(final E e)
   {
      final boolean result = getDecorated().add(e);

      if (result)
      {
         fireElementAdded(e);
      }
      else
      {
         fireElementReadded(e);
      }

      return result;
   }

   @Override
   public Iterator iterator()
   {
      return new EventSetIterator(getDecorated().iterator());
   }

   @SuppressWarnings("unchecked")
   @Override
   public boolean remove(final Object o)
   {
      final boolean result = getDecorated().remove(o);

      if (result)
      {
         fireElementRemoved((E) o);
      }

      return result;
   }

   protected class EventSetIterator implements Iterator
   {
      protected final Iterator _decorated;
      protected E _lastElement = null;

      public EventSetIterator(final Iterator decorated)
      {
         _decorated = decorated;
      }

      @Override
      public boolean hasNext()
      {
         return _decorated.hasNext();
      }

      @Override
      public E next()
      {
         _lastElement = _decorated.next();

         return _lastElement;
      }

      @Override
      public void remove()
      {
         _decorated.remove();

         fireElementRemoved(_lastElement);
      }
   }

   abstract protected void fireElementAdded(E element);

   abstract protected void fireElementReadded(E element);

   abstract protected void fireElementRemoved(E element);
}