BigDecimal类型的累加

// lastMonth.add(item.getNowMonthPlanSettle() != null ? item.getNowMonthPlanSettle() : new BigDecimal(0)); 这样累加会都是0
lastMonth = lastMonth.add(item.getNowMonthPlanSettle() != null ? item.getNowMonthPlanSettle() : new BigDecimal(0));