对包含双精度值和字符串值的哈希映射进行排序

Question

我收到了一个冬奥会项目的文本文件。它包含参赛队伍、参赛者姓名和分数。

FRAMae Berenice MEITE         455.455
CHNKexin ZHANG                454.584
UKRNatalia POPOVA             453.443
GERNathalie WEINZIERL         452.162
RUSEvgeny PLYUSHCHENKO        191.399
CANPatrick CHAN               189.718
CHNHan YAN                    185.527
CHNCheng & Hao                271.018
ITAStefania & Ondrej          270.317
USAMarissa & Simon            264.256
GERMaylin & Daniel            260.825
FRAFlorent AMODIO             179.936
GERPeter LIEBERS              179.615
ect....

唯一重要的数字是数字中的最后一位。对于每支球队，我需要将他们的总分加在一起，并显示前5名球队。

到目前为止的代码：

public class project2 {
public static void main(String[] args) throws IOException {
    // TODO Auto-generated method stub
    String[] array = new String[41];
    String[] info = new String [41];
    String[] stats = new String[41];    
    String[] team = new String[41];
            //.txt file location
            FileInput fileIn = new FileInput(); 
            fileIn.openFile("C:\Users\O\Desktop\turn in\team.txt");
            //txt file to array
            int i=0;
            String line = fileIn.readLine();
            array[i] = line; i++;
            while (line != null) { 
                line = fileIn.readLine();
                array[i] = line; i++;
            }
            System.out.println(array[1]);

            //Splitting up team/competitor name/score
            for (int j =0; j< 40; j++){
                team[j] = array[j].substring (0, 3).trim ();
                info[j] = array[j].substring (3, 30).trim ();
                stats[j] = array[j].substring (36).trim ();
            }

            //random outputs ive been using fore testing.
            System.out.println(team[1]);
            System.out.println(info[1]);
            System.out.println(stats[1]);
            MyObject ob = new MyObject();
            ob.setText(info[0]);
            ob.setNumber(7, 23);
            ob.setNumber(3, 456);
            System.out.println("Text is " + ob.getText() + " and number 3 is " + ob.getNumber(7));
             for (int j =0; j< 40; j++){
                    team[j] = array[j].substring (0, 3).trim ();
                    info[j] = array[j].substring (3, 30).trim ();
                    stats[j] = array[j].substring (36).trim ();
                }

                //team and score in hashmap
                double[] statsDub = new double[40];
                for (int k =1; k < 40; k++){
                statsDub[k] = Double.parseDouble(stats[k]);
                }
                Map<String,Double> totalScore = new HashMap<>();
                for (int j =0; j< 40; j++){
                      Double tmp = totalScore.get (team[j]);
                        if (tmp != null)
                        {
                            totalScore.put(team[j], statsDub[j]+tmp);
                        }
                        else
                                totalScore.put(team[j], statsDub[j]);
                        }
                 // Get a set of the entries
                  Set set = totalScore.entrySet();
                  // Get an iterator
                  Iterator i1 = set.iterator();
                  // Display elements
                  while(i1.hasNext()) {
                     Map.Entry me = (Map.Entry)i1.next();
                     System.out.print(me.getKey() + ": ");
                     System.out.println(me.getValue());




    }}}

            //if (totalScore.containsKey("COUNTRYNAME"))
            //    totalScore.put("COUNTRYNAME", totalScore.get("COUNTRYNAME") + playerScore);
            //else
            //    totalScore.put("COUNTRYNAME",0);

我得到这个输出：

GER: 17.0
USA: 27.0
ITA: 23.0
RUS: 37.0
CHN: 20.0
JPN: 24.0
FRA: 17.0
CAN: 32.0
UKR: 10.0
GBR: 8.0

我怎么能只按降序显示前5名的球队呢？

Answer 1

• 创建一个实现Comparator的类，该类可以基于Double部分在两个Map.Entry<String,Double>对象之间进行比较
• 使用该比较器创建一个TreeSet<Map.Entry<String,Double>>，它是有序集的实现
• 现在使用TreeSet的addAll方法将从totalScore.entrySet()获得的集合中的值相加
• 对结果集进行迭代，保留一个整数变量来计算迭代次数，并在5处停止

另一种选择是将集合复制到List<Map.Entry<String,Double>>，然后使用Collections.sort对其进行排序。它仍然需要一个comparator对象！