Question

uppose you have a pre-existing class Dieter that models a person trying to monitor diet and weight to improve his/her Body Mass Index (BMI) rating. The class has the following data and behavior:

Field/Constructor/Method	Description
private String name	the dieter's full name, such as "John Smith"
private int height	the dieter's height, in inches
private int weight	the dieter's weight, in pounds
public Dieter(String name, int h, int w)	makes a dieter with given name, height, weight
public String getName()	returns the dieter's name
public int getHeight()	returns the dieter's height
public int getWeight()	returns the dieter's weight
public double getBMI()	computes the dieter's Body Mass Index (BMI), which is (weight / height2) · 703
public void gain(int pounds)	called when the dieter gains weight
public void lose(int pounds)	called when the dieter loses weight

Make Dieter objects comparable to each other using the Comparable interface.

You are just writing a compreTo method for the class and not any other method.

Write the compareTo method for the class Dieter using the following criteria.

• Dieters are primarily compared by their BMI ratings;
• a dieter with a lower BMI is "less than" one with a higher BMI.
• If two dieters have the same BMI, the tie is broken by height; the shorter person is considered to be "less than" the taller one.
• If two dieters have the same BMI and height, the tie is broken by name. The dieter whose name comes first in alphabetical order is considered "less than" the one whose name comes later in ABC order.
• If the two dieters have the same BMI, height, and name, they are considered to be "equal." Your method should not modify any dieter's state. You may assume the parameter passed is not null  

Answer 1

// Dieter.java

public class Dieter implements Comparable<Dieter> {

   private String name; // the dieter's full name, such as "John Smith"
   private int height; // the dieter's height, in inches
   private int weight; // the dieter's weight, in pounds
  
   // constructor that creates a dieter with given name, height, weight
   public Dieter(String n, int h, int w)
   {
       name = n;
       height = h;
       weight = w;
   }
  
   // returns the dieter's name
   public String getName()
   {
       return name;
   }
  
   // returns the dieter's height
   public int getHeight()
   {
       return weight;
   }
  
   // returns the dieter's weight
   public int getWeight()
   {
       return weight;
   }
  
   // computes the dieter's Body Mass Index (BMI), which is (weight / height2) • 703
   public double getBMI()
   {
       return (((double)weight)/Math.pow(height,2))*703;
   }
  
   // method called when the dieter gains weight
   public void gain(int pounds)
   {
       weight += pounds;
   }
  
   // method called when the dieter loses weight
   public void lose(int pounds)
   {
       weight -= pounds;
       if(weight < 0)
           weight = 0;
   }

  
   /*
   * method to compare 2 Dieter and returns
   * < 0, if this Dieter < other
   * > 0, if this Dieter > other
   * = 0, if this Dieter = other
   */
   @Override
   public int compareTo(Dieter other) {
      
       // compare Dieter based on BMI
       if(getBMI() < other.getBMI())
           return -1;
       else if(getBMI() > other.getBMI())
           return 1;
       else
       {
           // BMI are equal
           // compare Dieter based on height
           // shorter person is considered to be "less than" the taller one
           if(height < other.height)
               return -1;
           else if(height > other.height)
               return 1;
           else // same height, compare the Dieters based on name
               // The dieter whose name comes first in alphabetical order is considered
               // "less than" the one whose name comes later in ABC order.
               return name.compareTo(other.name);
       }
   }
}

//end of Dieter.java