public static void increment(Calendar c,int field,int val){
  if (isMultiYear(field)) {
    c.add(Calendar.YEAR,-field * val);
  }
 else {
    c.add(field,val);
  }
}

public static void increment ( Calendar c , int field , int val ) { if ( isMultiYear ( field ) ) { c . add ( Calendar . YEAR , - field * val ) ; } else { c . add ( field , val ) ; } }
increment a calendar by a given number of time units .
