public int hashCode(){
  int hash1=x.hashCode();
  int hash2=y.hashCode();
  return 31 * hash1 + hash2;
}

public int hashCode ( ) { int hash1 = x . hashCode ( ) ; int hash2 = y . hashCode ( ) ; return 31 * hash1 + hash2 ; }
returns an integer hash code for this interval .
