java做成績排名表，如何實現同分同名次

要求計算綜合平均分

去除最高分和最低分，並且實現同分同名次

 

//去除最高分，和最低分，實現思路，

根據id 使用groupingby分組  然后循環分組的map   

接着根據分數進行排序，然后去除最高的和最低分，刪除list 第一條數據，以及最后一條數，這樣就把最高分，和最低分去除

 

然后統計平均分，實現思路，一樣重新根據id 使用groupingby 重新分組

然后循環數據合並，根據id為key，相同id的數據 進行分數相加

    public List<CompetitionWorkExhibitionPo1> getList(List<CompetitionWorkExhibitionPo1> list) {
        List<CompetitionWorkExhibitionPo1> list1 = new ArrayList<>();
        List<CompetitionWorkExhibitionPo1> list2 = new ArrayList<>();

        Map<Long, List<CompetitionWorkExhibitionPo1>> collect = list.stream().collect(Collectors.groupingBy(CompetitionWorkExhibitionPo1::getCompetitionUserId));//使用groupingby分組
        for (Map.Entry<Long, List<CompetitionWorkExhibitionPo1>> com : collect.entrySet()) {
            List<CompetitionWorkExhibitionPo1> li = com.getValue();
            li.sort(Comparator.comparing(CompetitionWorkExhibitionPo1::getCompetitionUserId).thenComparing(CompetitionWorkExhibitionPo1::getSum));//根據分數排序
            li.remove(0);//刪除list 第一條數據
            li.remove(li.size() - 1);//以及最后一條數
            list1.addAll(li);//然后把數據保存進一個新的list
        }
　　　　　
        Map<Long, List<CompetitionWorkExhibitionPo1>> collect1 = list1.stream().collect(Collectors.groupingBy(CompetitionWorkExhibitionPo1::getCompetitionUserId));//統計平均分，重新分組
        for (Map.Entry<Long, List<CompetitionWorkExhibitionPo1>> co : collect1.entrySet()) {
            List<CompetitionWorkExhibitionPo1> value = co.getValue();
            int inx = value.size();//保存list的長度，用戶計算平均分
            list2.addAll(//處理完保存到一個新的集合
                    value.stream()
                            // 表示id為key， 接着如果有重復的，那么從BillsNums對象o1與o2中篩選出一個，這里選擇o1，
                            // 並把id重復，需要將nums和sums與o1進行合並的o2, 賦值給o1，最后返回o1
                            .collect(Collectors.toMap(CompetitionWorkExhibitionPo1::getCompetitionUserId, a -> a, (o1, o2) -> {
                                o1.setSum(o1.getSum() + o2.getSum());//分數相加
                                o1.setCount(String.valueOf(inx));//把list的長度，賦值
                                return o1;
                            })).values().stream().collect(Collectors.toList())
            );
        }

        int count = mapper2.count();  //查詢最高點贊數
        DecimalFormat df = new DecimalFormat("0.00");//格式化小數
        for (CompetitionWorkExhibitionPo1 competitionWorkExhibitionPo1 : list2) {

　　　　　　　　//處理點贊得分
            competitionWorkExhibitionPo1.setGiveScore(competitionWorkExhibitionPo1.getPraiseCount() > 0 ? df.format((float) competitionWorkExhibitionPo1.getPraiseCount() / count) : String.valueOf(0));
　　　　　　　　//處理總分
            competitionWorkExhibitionPo1.setReviewScore(df.format((float) competitionWorkExhibitionPo1.getSum() / Integer.parseInt(competitionWorkExhibitionPo1.getCount())));
        }
        for (CompetitionWorkExhibitionPo1 competitionWorkExhibitionPo1 : list2) {
　　　　　　　　//處理綜合總分=點贊得分+總分
            competitionWorkExhibitionPo1.setComprehensiveScore(Double.valueOf(competitionWorkExhibitionPo1.getGiveScore()) + Double.valueOf(competitionWorkExhibitionPo1.getReviewScore()));
        }
        List<CompetitionWorkExhibitionPo1> competitionWorkExhibitionPo1s = CompetitionRankingService.fun1(list2);//調用方法，得出排名return list2;
    }

 

 

// 方法一:傳統的方法

排序：把不同成績保存map中，最后實體類根據map的key找到排名 存入實體排名里面

  public static List<CompetitionWorkExhibitionPo1> fun1(List<CompetitionWorkExhibitionPo1> stus) {
        // 按照成績排序
        stus.sort(new Comparator<CompetitionWorkExhibitionPo1>() {
            @Override
            public int compare(CompetitionWorkExhibitionPo1 s1, CompetitionWorkExhibitionPo1 s2) {
                return -Double.compare(s1.getComprehensiveScore(), s2.getComprehensiveScore());
            }
        });
        int rank = 1;//保存排名
        int index = 1;//排序號
        double lastScore = -1;// 最近一次的分

        for (int i = 0; i < stus.size(); i++) {
            CompetitionWorkExhibitionPo1 s = stus.get(i);
            if (Double.compare(lastScore, s.getComprehensiveScore()) != 0) { // 如果成績和上一名的成績不相同,那么排名+1
                lastScore = s.getComprehensiveScore();
                stus.get(i).setRank(rank++);//設置排名
                stus.get(i).setIndex(index++);//設置排序號
            }
        }
        stus.stream().forEach(System.out::println);
        return stus;
    }

/ 方法2: Java8開始支持的Lambada表達式配合 Stream API 來進行分組排序

  public static List<CompetitionWorkExhibitionPo1> fun2(List<CompetitionWorkExhibitionPo1> stus) {
        List<Map.Entry<Double, List<CompetitionWorkExhibitionPo1>>> list = stus.stream().collect(Collectors.groupingBy(CompetitionWorkExhibitionPo1::getComprehensiveScore)).entrySet()
                .stream().sorted((s1, s2) -> -Double.compare(s1.getKey(), s2.getKey())).collect(Collectors.toList());
        int rank = 1;//設置排名
        int index = 1;//設置排序號
        for (Map.Entry<Double, List<CompetitionWorkExhibitionPo1>> entry : list) {
            for (CompetitionWorkExhibitionPo1 competitionWorkExhibitionPo1 : entry.getValue()) {
                competitionWorkExhibitionPo1.setRank(rank++);
                competitionWorkExhibitionPo1.setIndex(index++);
            }
        }
        stus.stream().forEach(System.out::println);
        return stus;
    }