Question

在我的程序中，我正在从CSV文件读取数据，该文件遵循舞蹈组的模式，然后是该组中的舞者的模式。我正在努力按字母顺序对舞者的姓名进行排序。

public String listAllDancesAndPerformers() {

    // get CSV file for dances Data
    ArrayList<String> dancesData = getCSV("src/csvFiles/danceShowData_dances.csv");

    int lineNumber = 0;
    String result = "";

    //for each line in dances csv file
    for (String line : dancesData) {

        //split into two sections - [0] is name of dance & [1] is dancers
        String[] splitByTab = line.split("\t");


         //take the dancers [1] of splitByTab and split it by commas
         // this makes that seperatedNames[1], [2] etc are all the dancers
         //and i am supposed to sort the seperated names to print out alphabetticaly
        String[] separatedNames = splitByComma(splitByTab[1]);


        lineNumber++;
        result += lineNumber + ": ";
        result += (splitByTab[0].trim()) + "\n";



        result += (listAllDancersIn(splitByTab[0].trim())) + "\n";


    }

    return result;
}

列出所有舞者方法，该方法将输入一个舞蹈名称，然后打印出该舞蹈名称，然后在CSV文件的内部读取该舞者的内容

public String listAllDancersIn(String dance) {
    // get CSV file for dances Data
    ArrayList<String> dancesData = getCSV("src/csvFiles/danceShowData_dances.csv");

    String result = "";

    // for each line in dances csv file
    for (String line : dancesData) {

        // split into two sections - [0] is name of dance & [1] is dancers
        String[] splitByTab = line.split("\t");

        splitByTab[0] = splitByTab[0].trim();

        // if name of dance matches given dance name
        if (splitByTab[0].equals(dance)) {

            // split names of dancers into individual strings
            String[] separatedNames = splitByComma(splitByTab[1]);

            // iterate through names
            for (int i = 0; i < separatedNames.length; i++) {
                // append result with output of getDanceGroupMembers (and trim input)
                result += ", " + getDanceGroupMembers(separatedNames[i].trim());
            }
        }
    }

    // remove leading comma and space
    result = result.substring(2);

    return result;
}

Answer 1

在您的listAllDancersIn方法中，使用ArrayList代替您的result +=指令。

然后最后，您可以使用默认的sorter，它将按字母顺序排序：

Collections.sort(resultAsList);

如果您仍然希望此方法返回排序后的字符串而不是排序后的列表，则可以使用Join method这样操作：

return String.join(", ", resultAsList);

Answer 2

我认为您应该分割代码：

读取CSV文件并建立正确的数据结构；
将数据结构打印到控制台或String。

public static Map<String, Set<String>> listAllDancesAndPerformers() {
    final Pattern pattern = Pattern.compile("(?<group>\\w+)\\t+(?<dancers>.+)");
    final Pattern comma = Pattern.compile("\\s*,\\s*");
    Map<String, Set<String>> groups = new TreeMap<>();

    for (String line : getCSV("src/csvFiles/danceShowData_dances.csv")) {
        Matcher matcher = pattern.matcher(line);

        if (matcher.matches())
            groups.put(matcher.group("group"), new TreeSet<>(Arrays.asList(comma.split(matcher.group("dancers")))));
    }

    return groups;
}

如果danceShowData_dances.csv文件的内容是：

beginners   anna,maria,olga
mature      bob,marvin,peter

然后结果Map将包含：

"beginners" : ["anna", "maria", "olga"]
"mature" : ["bob", "marvin", "peter"]

最后，您可以创建将给定的Map转换为String并采用所需格式的方法：

public static String printToString(Map<String, Set<String>> groups) {
    int count = 1;
    StringBuilder buf = new StringBuilder();

    for (Map.Entry<String, Set<String>> entry : groups.entrySet()) {
        if (buf.length() > 0)
            buf.append('\n');

        buf.append(count++).append(':');
        buf.append(entry.getKey());

        if (!entry.getValue().isEmpty())
            buf.append('\n').append(String.join(", ", entry.getValue()));
    }

    return buf.toString();
}

输出：

1:beginners
anna, maria, olga
2:mature
bob, marvin, peter

Answer 3

Marius，请看下面的代码是否按预期工作。

import java.util.ArrayList;
import java.util.Collections;

public class SortDancers {

    public static void main(String[] args) {

        System.out.println(new SortDancers().listAllDancesAndPerformers());
    }

    public String listAllDancesAndPerformers() {

        ArrayList<String> dancesData = new ArrayList<String>();
        dancesData.add("Dance1 \t Kelly, Andrew, Nathan");
        dancesData.add("Dance2 \t John, Sally, Kevin, Abby");
        dancesData.add("Dance3 \t Laura, Benny, Jane");
        // I assume you get this kind of data from getCSV()

        int lineNumber = 0;
        String result = "";

        for (String line : dancesData) {

            String[] splitByTab = line.split("\t");

            String[] separatedNames = splitByTab[1].split(",");

            lineNumber++;
            result += lineNumber + ": ";
            result += (splitByTab[0].trim()) + "\n";

            ArrayList<String> separatedNamesList = new ArrayList<String>();
            for (int i = 0; i < separatedNames.length; i++) {
                separatedNamesList.add(separatedNames[i].trim());
            }

            Collections.sort(separatedNamesList);
            result += String.join(", ", separatedNamesList);
            result += "\n";
        }

        return result;
    }
}

在Java中按字母顺序对数组进行排序

3 个答案: