从数组打印信息，而不使用重复值

Question

我正在编写一个程序，它接收奥运奖牌数据，并打印出各种信息。就逻辑和结构而言，这个特定部分被证明有点困难。我正在尝试获取 String array 和 int array（它们都是在 main 方法中创建的），将它们传递给新方法，并打印出有关它们的信息。

我的数组如下（请注意String数组是按字母顺序排列的）：

        String[] country = {"Afghanistan", "Afghanistan", "Canada", "China", "Italy", "Mexico"};
        int[] totalMedals = {1, 2, 1, 1, 3, 2};

我想打印出来如下：

Afghanistan, 3 medal(s)
Canada, 1 medal(s)
China, 1 medal(s)
Italy, 3 medal(s)
Mexico, 2 medal(s)

我可以很容易地编写以这种格式列出的程序，但是出现不止一次的国家（在这个示例中...阿富汗）被列出的次数与它在数组中出现的次数一样多。正如所写，我的输出是：

Afghanistan, 1 medal(s)
Afghanistan, 2 medal(s)
Canada, 1 medal(s)
China, 1 medal(s)
Italy, 3 medal(s)
Mexico, 2 medal(s)

阿富汗被列出了两次（为了提供一个重要的背景，这是该计划的一小部分。该计划实际上也包含运动员的名字，但以不同的方式处理）。

任何人都可以就打印出我想要的输出的最佳方式向我提供一些帮助吗？

import java.util.*;
import java.io.*;

public class Project {

public static void main(String[] args) {
    String[] country = {"Afghanistan", "Afghanistan", "Canada", "China", "Italy", "Mexico"};
    int[] totalMedals = {1, 2, 1, 1, 3, 2};

    listCountryMedals(country, totalMedals);

}

    //List the grand total of medals for each country...display name only once
public static void listCountryMedals(String[] country, int[] totalMedals) {

    for (int i = 0; i < country.length; i++) {
        System.out.println(country[i] + ", " + totalMedals[i] + " medal(s)");            
    }
}

Answer 1

假设您只想使用数组和循环，您可以执行以下操作：

public static void listCountryMedals(String[] country, int[] totalMedals) {
  boolean[]seen = new boolean[country.length];
  for (int i = 0; i < country.length - 1; i++) {
      int medals = totalMedals[i];
      if (!seen[i]) {
          for(int j = i + 1; j < country.length; j++) {
             if (country[i].equals(country[j])) {
                 medals += totalMedals[j];
                 seen[j] = true; //I already took this country
             }
          }
          System.out.println(country[i] + ", " + medals + " medal(s)");
      }
      seen[i] = true;
  }
}

Answer 2

试试这个，

public static void listCountryMedals(String[] country, int[] totalMedals)
    {
        Map<String, Integer> countryMap = new HashMap<String, Integer>();

        for (int i = 0; i < country.length; i++)
        {
            Integer medals = countryMap.get(country[i]);
            Integer sum = (medals == null) ? totalMedals[i] : (totalMedals[i] + medals);
            countryMap.put(country[i], sum);
        }

        for (Map.Entry<String, Integer> countryMedals : countryMap.entrySet())
        {
            System.out.println(countryMedals.getKey() + ", " + countryMedals.getValue() + " medal(s)");
        }
    }

Answer 3

您应该采用面向对象的方法：

public class Country {

    private String name;
    private int medals;

    //getters/setters/constructors

}

然后就变得简单了：

List<Country> countries = new ArrayList<>();

//when you want to reference/print those:
for (Country c : countries) {
    System.out.println(String.format("%s, %d medals(s)", c.getName(), c.getMedals()));
}

Answer 4

我会使用LinkedHashMap 来按国家/地区汇总奖牌：

//List the grand total of medals for each country...display name only once
public static void listCountryMedals(String[] country, int[] totalMedals) {
    final Map<String, Integer> map = new LinkedHashMap<String, Integer>();


    for (int i = 0; i < country.length; i++) {
        if (!map.containsKey(country[i]))
            map.put(country[i], 0);
        map.put(country[i], map.get(country[i]) + totalMedals[i]); 
    }

    for (final Entry<String, Integer> entry : map.entrySet()) {
        System.out.println(entry.getKey() + ", " + entry.getValue() + " medal(s)");           
    }
}

与经典的HashMap 不同，LinkedHashMap 在迭代时将保留键顺序。您的国家/地区目前似乎已排序，因此您可能希望在打印时保持此顺序。

Answer 5

如下改变你的方法。

public static void listCountryMedals(String[] country, int[] totalMedals) {

     //Map to hold the conuntry anme and medal count pair
     Map<String,Integer> countryNameToMedalCountMap= new HashMap<String,Integer>();

      for (int i = 0; i < country.length; i++) {           
         if(countryNameToMedalCountMap.get(country[i]) == null) {
             countryNameToMedalCountMap.put(country[i],totalMedals[i]);
         } else {
             int count = map.get(country[i]);
             countryNameToMedalCountMap.put(country[i],count+totalMedals[i];
        }
     }

      //Print the map
      for(String counrty : countryNameToMedalCountMap.keySet()) {
          System.out.println(country+" "+ countryNameToMedalCountMap.get(country)+" medal(s).");
      }
}

注意：使用这种方法，国家名称将区分大小写。如果您想要不区分大小写，则必须设置一些机制。就像总是将地图键转换为小写并在查找时做同样的事情

Answer 6

您可以使用地图来存储这些信息，国家为键，奖牌数为值。

public static void listCountryMedals(String[] country, int[] totalMedals) 
{
    Map<String, Integer> countryMedalMap = new LinkedHashMap<String, Integer>();
    for (int i = 0; i < country.length; i++) 
    {
        String countryName = country[i];
        /**
         * If the country is already in the map, get the number of medal and add it up with value 
         * from totalMedals array for that country. Then put it back to map with the new medal count.
         */
        if(countryMedalMap.containsKey(countryName))
        {
            int medalCount = countryMedalMap.get(countryName) + totalMedals[i];
            countryMedalMap.put(countryName, medalCount);
        }
        /**
         * If the country is not in the map, put it into map with its medal count.
         */
        else
        {
            countryMedalMap.put(countryName, totalMedals[i]);
        }
    }

    printMap(countryMedalMap);
}

/**
 * Print the map
 * 
 * @param map
 */
public static void printMap(Map<String, Integer> map)
{
    for (String countryName : map.keySet())
    {
        System.out.println(String.format("%s, %s medal(s)", countryName, map.get(countryName)));
    }
}