@Override public void agg(Object newVal){
  if (firstTime) {
    aggVal=(BigDecimal)newVal;
    firstTime=false;
  }
 else {
    aggVal=aggVal.add((BigDecimal)newVal);
  }
}

@ Override public void agg ( Object newVal ) { if ( firstTime ) { aggVal = ( BigDecimal ) newVal ; firstTime = false ; } else { aggVal = aggVal . add ( ( BigDecimal ) newVal ) ; } }
this method will update the aggval it will add new value to aggval
