package cz.cuni.amis.utils.collections;
   
   import java.util.Collection;
   
   /**
    * Simple listener called for each element that has changed even in batch updates.
    * @author ik
    */
   public abstract class ElementListener<T> extends SimpleListener<T> {
  
      /**
       * Called each time an element changes.
       * @param elem
       * @param added
       */
      public abstract void elementChanged(T elem, boolean added);
  
      @Override
      protected void changed(Collection<T> collection, Collection<T> added, Collection<T> removed) {
          Collection<T> changed = null;
          boolean addedFlag = true;
  
          if(added != null) {
              changed = added;
          } else {
              changed = removed;
              addedFlag = false;
          }
  
          for (T elem : changed) {
              elementChanged(elem, addedFlag);
          }
      }
  }