Hashing

• Must be compatible with equals:
  if x.equals(y), then x.hashCode() == y.hashCode()
• Object.hashCode hashes memory address
• NOT compatible with redefined equals
• Remedy: Hash all fields and combine codes:
  

  public class Employee 
  { 
     public int hashCode() 
     { 
        return name.hashCode() 
           + new Double(salary).hashCode(); 
     } 
     ... 
  }