Sorting Real Data

• Several classes in Java (e.g. String and Date) implement Comparable
• You can implement Comparable interface for your own classes

  public class Coin implements Comparable
  {
     . . .
     public int compareTo(Object otherObject)
     {
        Coin other = (Coin) otherObject;
        if (value < other.value) return -1;
        if (value == other.value) return 0;
        return 1;
     }
     . . .
  }