关于java:java开发中遇到的一些问题

1.HashMap相干问题

1.1HashMap存key，value，key会有反复的，value会有多个值，选取此形式进行存取，动静获取key，value取list，若满足条件，list始终add，key笼罩掉之前的，list始终在减少。

HashMap<String, List<ScatteredPrescriptionDetail>> preDetailMap=new HashMap<String, List<ScatteredPrescriptionDetail>>();
            for (int i=0;i<prescriptionDetailList.size();i++) {
                ScatteredPrescriptionDetail scatteredPrescriptionDetail = prescriptionDetailList.get(i);
                if("Y".equals(scatteredPrescriptionDetail.getIsSubOrder())){
                    if (!preDetailMap.containsKey(scatteredPrescriptionDetail.getParentOrderSN())) {
                        List<ScatteredPrescriptionDetail> tmpList=new ArrayList<ScatteredPrescriptionDetail>();
                        tmpList.add(scatteredPrescriptionDetail);
                        preDetailMap.put(scatteredPrescriptionDetail.getParentOrderSN(), tmpList);
                    }
                    else {
                        System.out.println();
                        preDetailMap.get(scatteredPrescriptionDetail.getParentOrderSN()).add(scatteredPrescriptionDetail);
                    }
                }
                else if("N".equals(scatteredPrescriptionDetail.getIsSubOrder())){
                    faList.add(scatteredPrescriptionDetail);
                }
            }