// Newer version of the Measurable interface now includes a static method
// and a default method - requires Java 8 or newer

/**
 *   Describes any class whose objects can be measured
 */
public interface Measurable
{
   /**
    * Computes the measure of the object.
    * @return the measure
    */
   double getMeasure();       // abstract method
   
   /**
    * Computes and returns the average measure for an array of Measurables
    * @param list an array of Measurables
    * @return the average measure for the objects in the array
    */
   static double getAverage(Measurable [] list)
   {
      // note to students: a static method, called just like static methods 
      // in classes, using the interface name as the "handle"
      
      if (list.length == 0)            // if list is empty...
         return 0.0 ;                  // ...ain't no average
      
      // here if list is not empty
      
      double sum = 0.0 ;               // accumulates sum of measures
      
      for (Measurable object : list)   // for each Measurable object in list...
      {
         sum += object.getMeasure() ;  // ...get the measure and add to sum
      }
      return sum / list.length ;       // compute and return average
   }
   
   /**
    * Is the measure of this object greater than the measure of another?
    * @param other the Measurable to which this object is compared
    * @return true if the measure of this object > the measure of other; else
    * returns false
    */
   default boolean isGreaterThan(Measurable other)
   // Note to students: a default method.  If not overridden in an implementing
   // class, that class "inherits" this version       
   {
      return this.getMeasure() > other.getMeasure() ;
   }   
}