Question

我想根据他们的观点对足球俱乐部的顺序进行排序。我创建了一个类，它从互联网获取值并处理该值以根据获胜，失败和绘制的数量计算点数。然后我想按顺序将标题及其数据写入文本文件。我为20个不同的俱乐部创建了20个不同的实例但是，我不知道对订单进行排序的最佳方法是什么。

import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class CalculateStandings {
    private int matches;
    private int homeWin;
    private int homeDraw;
    private int homeLost;
    private int homeForGoal;
    private int homeAgainstGoal;
    private int awayWin;
    private int awayDraw;
    private int awayLost;
    private int awayForGoal;
    private int awayAgainstGoal;
    private int point;
    private int totalWin;
    private int totalLost;
    private int totalDraw;
    private int totalAgainstGoal;
    private int totalForGoal;


    void getResult(String team_Name) {
        try {
            URL url = new URL("https://raw.githubusercontent.com/openfootball/eng-england/master/2017-18/1-premierleague-i.txt");
        Scanner input = new Scanner(url.openStream());
        while (input.hasNext()) {
            String mydata = input.nextLine();
            if (mydata.contains(team_Name)) {
                Pattern pattern = Pattern.compile("[0-9]{1,2}-[0-9]{1,2}");
                Matcher matcher = pattern.matcher(mydata);
                String result;
                if (matcher.find()) {
                    matches += 1;
                    result = matcher.group();

                    if (mydata.startsWith("  " + team_Name)) {
                        homeForGoal += Integer.parseInt(Character.toString(result.charAt(0)));
                        homeAgainstGoal += Integer.parseInt(Character.toString(result.charAt(2)));
                    } else if (mydata.endsWith("  " + team_Name)) {
                        awayForGoal += Integer.parseInt(Character.toString(result.charAt(2)));
                        awayAgainstGoal += Integer.parseInt(Character.toString(result.charAt(0)));
                    }

                    if (Integer.parseInt(Character.toString(result.charAt(0))) > Integer.parseInt(Character.toString(result.charAt(2)))) {
                        if (mydata.startsWith("  " + team_Name)) {
                            point += 3;
                            homeWin += 1;
                        } else if (mydata.endsWith("  " + team_Name)) {
                            awayLost += 1;
                        }
                    } else if (Integer.parseInt(Character.toString(result.charAt(0))) < Integer.parseInt(Character.toString(result.charAt(2)))) {
                        if (mydata.startsWith("  " + team_Name)) {
                            homeLost += 1;
                        } else if (mydata.endsWith("  " + team_Name)) {
                            point += 3;
                            awayWin += 1;
                        }

                    } else {
                        if (mydata.startsWith("  " + team_Name)) {
                            point += 1;
                            homeDraw += 1;
                        } else if (mydata.endsWith("  " + team_Name)) {
                            point += 1;
                            awayDraw += 1;
                        }
                    }
                }
            }
        }
        totalWin = homeWin + awayWin;
        totalLost = homeLost + awayLost;
        totalDraw = homeDraw + awayDraw;
        totalAgainstGoal = homeAgainstGoal + awayAgainstGoal;
        totalForGoal = homeForGoal + awayForGoal;

    } catch (MalformedURLException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

}
}

这是我的主要课程：

public class Launcher {
public static void main(String[] args) {

    CalculateStandings Arsenal = new CalculateStandings();
    CalculateStandings Tottenham = new CalculateStandings();
    CalculateStandings WHam = new CalculateStandings();
    CalculateStandings CPalace = new CalculateStandings();
    CalculateStandings MU = new CalculateStandings();
    CalculateStandings MC = new CalculateStandings();
    CalculateStandings Everton = new CalculateStandings();
    CalculateStandings Liv = new CalculateStandings();
    CalculateStandings WBAlbion = new CalculateStandings();
    CalculateStandings NU = new CalculateStandings();
    CalculateStandings Stoke_City = new CalculateStandings();
    CalculateStandings Southampton = new CalculateStandings();
    CalculateStandings Leicester_City = new CalculateStandings();
    CalculateStandings Bournemouth = new CalculateStandings();
    CalculateStandings Watford = new CalculateStandings();
    CalculateStandings Brighton = new CalculateStandings();
    CalculateStandings Burnley = new CalculateStandings();
    CalculateStandings Huddersfield = new CalculateStandings();
    CalculateStandings Swansea = new CalculateStandings();


    Arsenal.getResult("Arsenal FC");
    Tottenham.getResult("Tottenham Hotspur");
    WHam.getResult("West Ham United");
    CPalace.getResult("Crystal Palace");
    MU.getResult("Manchester United");
    MC.getResult("Manchester City");
    Everton.getResult("Everton FC");
    Liv.getResult("Liverpool FC");
    WBAlbion.getResult("West Bromwich Albion");
    NU.getResult("Newcastle United");
    Stoke_City.getResult("Stoke City");
    Southampton.getResult("Southampton FC");
    Leicester_City.getResult("Leicester City");
    Bournemouth.getResult("AFC Bournemouth");
    Watford.getResult("Watford FC");
    Brighton.getResult("Brighton & Hove Albion");
    Burnley.getResult("Burnley FC");
    Huddersfield.getResult("Huddersfield Town");
    Swansea.getResult("Swansea City");

}

}

我正在考虑使用Getter将值存储到多个数组中，然后使用排序算法（如Bubble sort）对它们进行排序。但是，正如您所看到的，每个实例中的实例数和字段数很多，使用Getter手动将它们写入数组需要花费太多时间。因此，我想问你是否有更优化的方法。

Answer 1

使用List而不是数组。您还应该检查Comparable接口以及如何使用它。以后您可以在List上使用sort方法。

https://docs.oracle.com/javase/7/docs/api/java/lang/Comparable.html

Answer 2

您可以使用：

ArrayList < CalculateStandings > footballClubs = new ArrayList < CalculateStandings >();

在主类中创建对象数组，然后使用

void add(footballClubName: CalculateStandings)

将足球俱乐部实例添加到arrayList的方法。

- 强制对对象进行排序的下一步是通过编辑类的头来将ComplateStandings类实现到Comparable接口

class CalculateStandings implements Comparable < CalculateStandings >

并覆盖类体中compareTo方法的实现，以便如何比较此类的实例。就像这个

@Override
public int compareTo(CalculateStandings o) {
      if(somthing_field(as_your_calculations) > o.somthing_field)
         return 1;
      else if (the_something_field < o.something_field)
         return -1;
      else
         return 0;
}

- 然后在主类中轻松使用java.util.Collections。 sort（arraylist）以递增顺序对其进行排序，如此

java.util.Collections.sort(footballClubs);

然后如果你想按顺序递减它，你可以使用for循环来反转它。

这就是全部，但我对你的代码有一个侧面说明，你可以缩短它并通过使用带有args的教师而不是这个无法教练来集中阅读，并使用俱乐部名称字符串作为你的args和在教师的实现中使用你的计算而不需要使用实例方法，

public CalculateStandings(String footballClubName) {
   //put your calculations here and assign the class fields.
}

只需使用教师实例化一个并将它们添加到数组中，就像这样

footballClubs.add(new CalculateStandings(footballClubName));

我希望它有所帮助。

Answer 3

你可以有一个单独的地图，其中俱乐部名称作为键，点数作为值，你可以使用lambdas打印出表格，这里是一个根据点（降序）对俱乐部进行排序的例子：

package com.company;

import java.util.HashMap;
import java.util.Map;

public class Main {

    private static int rank = 1;

    public static void main(String[] args) {

        Map<String, Integer> teams = new HashMap<>(){{
            put("Arsenal", 54);
            put("Chelsea", 44);
            put("Manchester United", 52);
            put("Liverpool", 49);
            put("Tottenham", 50);
        }};

        teams.entrySet().stream()
                        .sorted((x,y) -> y.getValue().compareTo(x.getValue()))
                        .forEach(n -> System.out.println(rank++ + ". " + n.getKey() + " with " + n.getValue() + " points."
        ));

    }
}

输出结果为：

阿森纳得到54分。
曼联得到52分。
托特纳姆得到50分。
利物浦得到49分。
切尔西得到44分。

如果您有任何其他问题，请在评论中问我。

对来自同一类的不同实例的值进行排序

3 个答案: