import java.beans.*;

/** 
 * The Max class finds and keeps track of the maximum value
 * in an array of Doubles
 *
 *  @author Stuart Hansen
 *  @version September 2008
 */
public class Max
{   
   // We maintain the maximum in order to have an old
   // maximum for the property change event
   private Double maximum;

   // We use pcs to facilitate our property change events
   private PropertyChangeSupport pcs;

   // The default constructor
   public Max()
   {
      maximum = new Double (Double.NaN);
      pcs = new PropertyChangeSupport (this);
   }

   // Return the current Maximum
   public Double getMaximum()
   {
      return maximum;
   }

   // Return the maximum as a String
   public String toString()
   {
      return maximum.toString();
   }

   // Find the average of an enumeration of Doubles
   public Double findMax(Double [] dArr)
   {
      Double oldMax = maximum;
      
      if (dArr.length > 0)
      {
         Double tempMax = dArr[0];
         for (Double d : dArr)
         {
            if (d > tempMax)
               tempMax = d;
         }
         maximum = tempMax;
      }
      else
         maximum = Double.NaN;
      
      firePropertyChange (new PropertyChangeEvent (this, "maximum", 
                     oldMax, maximum));
      return maximum;
   }

   // Fire a property change
   public void firePropertyChange (PropertyChangeEvent e)
   {
      pcs.firePropertyChange(e);
   }

   // Add a property change listener
   public void addPropertyChangeListener(PropertyChangeListener pcl)
   {
      pcs.addPropertyChangeListener(pcl);
   }

   // Delete a property change listener
   public void removePropertyChangeListener(PropertyChangeListener pcl)
   {
      pcs.removePropertyChangeListener(pcl);
   }
 }