奥运会java编码

Question

我正在编写一个程序，我必须计算每个国家/地区的金牌数。输入将来自一个文件，我必须处理该文件。 第一行是国家代码，第二行是事件类型，第三行是事件。输入是这样的：

CHN 
Diving 
Women's 10m Platform 
CAN 
Rowing 
Men's Eight 
CHN
Rowing
Women's Quadruple Sculls

预期的输出应该是这样的：

Count of gold medallists by country:
CHN - 2
CAN - 1

Count of gold medallists by event type:
Diving - 1
Rowing - 2

好的，所以我创建了一类金牌，它将根据事件类型为每个国家创建一个新的实例对象。我的代码在这里：

class GoldMedals {
  private String country;
  private String eventType;
  private String event;
  private int medalCount;

 public GoldMedals(String name, String type, String event) {
   this.country = name;
   this.eventType = type;
   this.event = event;
   medalCount = 1;
}

public boolean matchDetails(String countryName, String type){
return (country.equals(countryName) && eventType.equals(type));
}

我的主要方法在这里：

try {
  input = new BufferedReader(new FileReader ("textfile.txt"));
  country = input.readLine();
  while(country!=null) {
    eventType = input.readLine();
    event = input.readLine();
    match = findMatch(winners, size, country, eventType);
    if(match == null) {
    winners[size] = new GoldMedals(country, eventType, event);
    size++;
      //match.addMedal();
    } //else {

        //match.addMedal();          
    //}
    //match.addMedal();
    country = input.readLine();
  }

  input.close();
} catch (IOException ioe) {
  System.out.println(ioe.getMessage());

我还添加了一个静态方法，以确保我们不会创建已经存在的对象。 （冗余对象）

public static GoldMedals findMatch(GoldMedals[] winners, int size, String country, String type) {
  GoldMedals result = null;
  int pos;

  pos = 0;
  while (pos < size && result == null) {
    if (winners[pos].matchDetails(country, type)) {
     result = winners[pos];
  } else {
     pos++;
  }
 }
  return result;
}

我想知道的是如何获得所需的输出。因为现在我得到了这个输出：

ITA- 1- Fencing- Women's Individual Foil
POL- 1- Rowing- Men's Quadruple Sculls
KEN- 1- Athletics- Men's Marathon 
CHN- 1- Diving- Men's 3m Springboard
TUN- 1- Swimming- Men's 1500m Freestyle
CHN- 1- Canoe/Kayak - Flatwater- Canoe Double (C2) 500m Men
CHN- 1- Diving- Men's Synchronised 3m Springboard 
USA- 1- Gymnastics Artistic- Women's Individual All-Around
RUS- 1- Synchronized Swimming- Duet

这是我编程的。我需要有关如何获得每个国家/地区的总金牌以及根据赛事类型获得金牌的帮助。 简而言之，我怎样才能获得上述所需的输出。 如果您在我的问题上需要帮助，我可以进一步解释。提示将不胜感激。

Answer 1

删除medalCount 字段。你的类应该只代表传入的数据。

然后您要构建两个Map<String, Long> 对象，其中键是国家代码或事件类型，值是键的计数。

使用 Java 8 流，这相当简单：

List<GoldMedals> allMedals = loadMedalsFromFile();

Map<String, Long> byCountry = allMedals.stream()
        .collect(Collectors.groupingBy(GoldMedals::getCountry,
                                       Collectors.counting()));

Map<String, Long> byEventType = allMedals.stream()
        .collect(Collectors.groupingBy(GoldMedals::getEventType,
                                       Collectors.counting()));

Answer 2

如果您无法使用地图。你可以试试下面的代码：

--金牌

public class GoldMedals {
    private String country;
    private String eventType;
    private String event;
    private int medalCount;

    public GoldMedals(String name, String type, String event) {
        this.country = name;
        this.eventType = type;
        this.event = event;
        medalCount = 1;
    }

    /**
     * @return the country
     */
    public String getCountry() {
        return country;
    }

    /**
     * @param country the country to set
     */
    public void setCountry(String country) {
        this.country = country;
    }

    /**
     * @return the eventType
     */
    public String getEventType() {
        return eventType;
    }

    /**
     * @param eventType the eventType to set
     */
    public void setEventType(String eventType) {
        this.eventType = eventType;
    }

    /**
     * @return the event
     */
    public String getEvent() {
        return event;
    }

    /**
     * @param event the event to set
     */
    public void setEvent(String event) {
        this.event = event;
    }

    /**
     * @return the medalCount
     */
    public int getMedalCount() {
        return medalCount;
    }

    /**
     * @param medalCount the medalCount to set
     */
    public void setMedalCount(int medalCount) {
        this.medalCount = medalCount;
    }

    public boolean matchDetails(String countryName, String type){
        return (country.equals(countryName) && eventType.equals(type));
    }

}

--GoldByCriteria

public class GoldByCriteria {

    private String country;
    private int goldMedals;

    public GoldByCriteria() {}

    public GoldByCriteria(String country, int goldMedals) {
        this.country = country;
        this.goldMedals = goldMedals;
    }

    /**
     * @return the country
     */
    public String getCountry() {
        return country;
    }
    /**
     * @param country the country to set
     */
    public void setCountry(String country) {
        this.country = country;
    }
    /**
     * @return the goldMedals
     */
    public int getGoldMedals() {
        return goldMedals;
    }
    /**
     * @param goldMedals the goldMedals to set
     */
    public void setGoldMedals(int goldMedals) {
        this.goldMedals = goldMedals;
    }

    /* (non-Javadoc)
     * @see java.lang.Object#hashCode()
     */
    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + ((country == null) ? 0 : country.hashCode());
        return result;
    }

    /* (non-Javadoc)
     * @see java.lang.Object#equals(java.lang.Object)
     */
    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        GoldByCriteria other = (GoldByCriteria) obj;
        if (country == null) {
            if (other.country != null)
                return false;
        } else if (!country.equals(other.country))
            return false;
        return true;
    }

    /* (non-Javadoc)
     * @see java.lang.Object#toString()
     */
    @Override
    public String toString() {
        return country + " - " + goldMedals;
    }

}

--实用程序

import java.util.ArrayList;
import java.util.List;

public class Util {

    /**
     * base on the criteria to get the number of gold
     * 
     * */
    public static final GoldByCriteria getGoldByCriteria(List<GoldByCriteria> list, String criteria) {
        for (GoldByCriteria goldByCriteria : list) {
            if(goldByCriteria.getCountry().equals(criteria)) {
                return goldByCriteria;
            }
        }
        return null;
    }

    /**
     * group by Country
     * */
    public static final List<GoldByCriteria> getGoldMedalsByCountry(List<GoldMedals> goldMedals) {
        List<GoldByCriteria> result = new ArrayList<GoldByCriteria>();
        for (GoldMedals e : goldMedals) {
            GoldByCriteria goldByCountry = Util.getGoldByCriteria(result, e.getCountry());
            if( goldByCountry != null) {
                goldByCountry.setGoldMedals(goldByCountry.getGoldMedals() + 1);
            } else {
                GoldByCriteria oneGold = new GoldByCriteria();
                oneGold.setCountry(e.getCountry());
                oneGold.setGoldMedals(e.getMedalCount());
                result.add(oneGold);
            }
        }
        return result;
    }


    /**
     * group by type
     * */
    public static final List<GoldByCriteria> getGoldMedalsByType(List<GoldMedals> goldMedals) {
        List<GoldByCriteria> result = new ArrayList<GoldByCriteria>();
        for (GoldMedals e : goldMedals) {
            GoldByCriteria goldByCountry = Util.getGoldByCriteria(result, e.getEventType());
            if( goldByCountry != null) {
                goldByCountry.setGoldMedals(goldByCountry.getGoldMedals() + 1);
            } else {
                GoldByCriteria oneGold = new GoldByCriteria();
                oneGold.setCountry(e.getEventType());
                oneGold.setGoldMedals(e.getMedalCount());
                result.add(oneGold);
            }
        }
        return result;
    }

}

--主要

import java.util.ArrayList;
import java.util.List;

public class Main {
    public static void main(String[] args) {
        List<GoldMedals> goldMedals = new ArrayList<GoldMedals>();

        GoldMedals one = new GoldMedals("ITA", "Fencing", "Women's Individual Foil");
        GoldMedals two = new GoldMedals("POL", "Rowing", "Men's Quadruple Sculls");
        GoldMedals three = new GoldMedals("CHN", "Diving", "Men's 3m Springboard");
        GoldMedals four = new GoldMedals("CHN", "Diving", "Men's Synchronised 3m Springboard");

        goldMedals.add(one);
        goldMedals.add(three);
        goldMedals.add(two);
        goldMedals.add(four);

        //by country 
        List<GoldByCriteria> byCountries = Util.getGoldMedalsByCountry(goldMedals);

        for (GoldByCriteria goldByCountry : byCountries) {
            System.out.println(goldByCountry);
        }

        System.out.println("------------");
        //by Type

        List<GoldByCriteria> byType = Util.getGoldMedalsByType(goldMedals);

        for (GoldByCriteria goldByType : byType) {
            System.out.println(goldByType);
        }
    }
}

您应该将 GoldByCriteria 中的属性“country”更改为更好的名称，例如“criteria”。为了一个快速的代码，我用国家测试了它。

希望对您有所帮助。