public class DomainRange {
   protected Object d;
   protected Object r;

   public DomainRange(Object d, Object r) {
      if (d == null) throw new Error("Null domain");
      this.d = d;
      this.r = r;
   }

   public Object getDomain()      { return d;    }
   public Object getRange()       { return r;    }
   public void setRange(Object r) { this.r = r;  }

   public boolean matchesDomain(Object probe) {
     return d.equals(probe);
   }

   public String toString() {
      return "("+d+","+r+")";
   }
}