java语法使用小技巧-保留两位小数-用group对list数据分组取和

如何用java对float类型数字保留两位小数：

 

Float sumFlowTotalTime = 104.17F;
        Float sumStartNum =19.0F;
        Float rate = Math.round(((sumFlowTotalTime/sumStartNum)*100))/100f;
        System.out.println(rate);

打印结果：5.48

 

java用group对list数据分组取和：

List<OrgApprovedDetail> approvedList = orgApprovedNumList.stream()
                .collect(Collectors.groupingBy(FandOrgApprovedNum::getOrgCode)).entrySet().stream()
                .map(entry -> {
                    String orgCode = entry.getKey();
                    int sumStopNum = entry.getValue().stream()
                            .mapToInt(f -> Integer.parseInt(f.getStopNum())).sum();
                    int sumApprovedNum1 = entry.getValue().stream()
                            .mapToInt(f -> Integer.parseInt(f.getApprovedNum())).sum();
                    int sumExtendedNum1 = entry.getValue().stream()
                            .mapToInt(f -> Integer.parseInt(f.getExtendedNum())).sum();
                    int quickApprovedNum1 = entry.getValue().stream()
                            .mapToInt(f -> Integer.parseInt(f.getQuickApprovedNum())).sum();
                    int sumReworkNum1 = entry.getValue().stream()
                            .mapToInt(f -> Integer.parseInt(f.getReworkNum())).sum();
                    float extendedRate1 = 0;
                    if (sumApprovedNum1 > 0) {
                        extendedRate1 = (float) sumExtendedNum1 / (float)sumApprovedNum1;
                    }

                    OrgApprovedDetail orgApprovedNum =new OrgApprovedDetail();
                    orgApprovedNum.setOrgCode(orgCode);
                    orgApprovedNum.setStopNum(sumStopNum);
                    orgApprovedNum.setApprovedNum(sumApprovedNum1);
                    orgApprovedNum.setExtendedNum(sumExtendedNum1);
                    orgApprovedNum.setQuickApprovedNum(quickApprovedNum1);
                    orgApprovedNum.setReworkNum(sumReworkNum1);
                    orgApprovedNum.setExtendedRate(extendedRate1);
                    return orgApprovedNum;
                }).collect(Collectors.toList());