public class ComparableDemo1
{
   public static void main(String[] args)
   {
      HighSchoolStudent student1 = new HighSchoolStudent(3.0, "Angie", 56);
      HighSchoolStudent student2 = new HighSchoolStudent(2.9, "Bill", 72);
      
      if (student1.compareTo(student2) > 0)
      {
         System.out.println(student1 + " IS GREATER THAN " + student2);
      }
      else if (student1.compareTo(student2) < 0)
      {
         System.out.println(student1 + " IS LESS THAN " + student2);
      }
      else
      {
         System.out.println(student1 + " IS EQUAL TO " + student2);
      }
      
      ElementarySchoolStudent student3 = new ElementarySchoolStudent(100, "Colleen");
      ElementarySchoolStudent student4 = new ElementarySchoolStudent(12, "David");
      
      if (student3.compareTo(student4) > 0)
      {
         System.out.println(student3 + " IS GREATER THAN " + student4);
      }
      else if (student3.compareTo(student4) < 0)
      {
         System.out.println(student3 + " IS LESS THAN " + student4);
      }
      else
      {
         System.out.println(student3 + " IS EQUAL TO " + student4);
      }
      
   }// end of main method
   
}// end of ComparableDemo1 class

////////////////////////////////////////////////////////

class HighSchoolStudent implements Comparable
{
   public HighSchoolStudent(double gpa, String name, int height)
   {
      myGPA = gpa;
      myName = name;
      myHeight = height;
   }

   public int compareTo(Object other)
   {
      if (this.myGPA > ((HighSchoolStudent) other).myGPA)
      {
         return 1;
      }
      else if (this.myGPA < ((HighSchoolStudent) other).myGPA)
      {
         return -1;
      }

      return 0;

      // return this.myHeight - ((HighSchoolStudent) other).myHeight;      // Why won't this single line return statement work for myGPA?
      // return this.myName.compareTo(((HighSchoolStudent) other).myName); // Is compareTo a recursive method?
   }
 
   public String toString()
   {
      return "name = " + myName + " GPA = " + myGPA + " height = " + myHeight;
   }

   private double myGPA;
   private String myName;
   private int myHeight;      // in inches
}

////////////////////////////////////////////////////////

class ElementarySchoolStudent implements Comparable
{
   public ElementarySchoolStudent(int workEthic, String name)
   {
      myWorkEthic = workEthic;
      myName = name;
   }

   public int compareTo(Object other)
   {
      return this.myWorkEthic - ((ElementarySchoolStudent) other).myWorkEthic; 
   }
 
   public String toString()
   {
      return "name = " + myName + " work ethic = " + myWorkEthic;
   }

   private int myWorkEthic;
   private String myName;
}