public class Contract {
 private int totalCost; 
 private int hoursLeft; 
 private String employer; 
 private static int hourlyRate;  
 
 public Contract(String employer, int hours){ 
  this.employer = employer; 
  this.hoursLeft = hours; 
  this.totalCost = Contract.hourlyRate * hours; 
 } 
 //... 

 public static void changeRate(int newRate){ 
  Contract.hourlyRate = newRate; 
 }
}