src/Weight.java

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