src/Weight.java

   1 public class Weight implements Comparable<Weight> {
   2     private int weight;
   3
   4     Weight() {
   5     }
   6
   7     Weight(int weight) {
   8         setWeight(weight);
   9     }
  10
  11     public int getWeight() {
  12         return weight;
  13     }
  14
  15     public void setWeight(int weight) {
  16         if (validateWeight(weight)) {
  17             this.weight = weight;
  18         } else {
  19             throw new IllegalArgumentException("Weight cannot be negative or zero");
  20         }
  21     }
  22
  23     private boolean validateWeight(int weight) {
  24         return (weight > 0);
  25     }
  26
  27     @Override
  28     public int compareTo(Weight weight) {
  29         int distance = weight.weight - this.getWeight();
  30         if (distance >= 0)
  31             return distance;
  32         else
  33             return -distance;
  34     }
  35 }