java - 如何使用嵌套 for 循环将数组值打印到 CSV 文件？

Question

我尝试对我的问题进行简单修复，将数组打印到 .csv 文件并替换某些字符，但后来我注意到我不应该在输出中的逗号前后使用任何空格。
我不能使用替换，否则所有标题标签也将有零个空格，因此我需要帮助直接从嵌套的 for 循环中获取值。

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

public class HW01 {
    public static void main(String args[]) throws IOException {

        // Create a 1D array to hold header labels
        String headerLabels[] =  
            {"COURSE ID", "TEAM ID", "STUDENT FIRST NAME",
             "STUDENT LAST NAME", "STUDENT ID", "ASSIGNMENT ID",
             "DATE SUBMITTED", "TIME SUBMITTED", "SUBMITTED BY"
            };

        // Create a 2D array to hold header values
        String headerValues[][] =
            {
            {"CMPS280-02", "Invokers01", "James", "Brown", "w0479045", "H01", "8/25/2017", "1:14PM", "James Brown"},
            {"CMPS280-01", "Winners03", "Jacob", "Harley", "w0389342", "H03", "8/23/2017", "7:24PM", "Jacob Harley"},
            {"SE101-02", "CodeIt00", "Keith", "Dillinger", "w0782345", "S04", "8/25/2017", "1:23AM", "Keith Dillinger"}
            };

        // Create an int to hold number of students
        int students = headerValues.length;

        // Array loop to create student .csv files
        for (int i = 0; i < headerValues.length; i++){
            for (int j = 0; j < students; j++){

            // Create new .csv file and store in SUBMIT folder
            String path = "SUBMIT/"+headerValues[i][0]+"_"+headerValues[i][5]+"_"+headerValues[i][1]+"_"+headerValues[i][4]+".csv";
                File file = new File(path);
                PrintWriter writer = new PrintWriter(file);

                // Print headerLabels and headerValues for each student into .csv files
                writer.println(Arrays.toString(headerLabels).replace("[", "").replace("]", "").replace(" , " , ","));
                writer.println(Arrays.toString(headerValues[i]).replace("[", "").replace("]", "").replace("  ,  ", ","));
                writer.close();
            }
        }

    }
 }

Answer 1

嵌套循环并不是问题所在。您尝试编写内容的顺序是。我假设您只需要为所有学生准备 1 个文件，而不是 i*j 文件。每个学生一个。

例如，

    // Create student .csv files and store in SUBMIT folder
    String path = "SUBMIT/students.csv";
    try (PrintWriter writer = new PrintWriter(new File(path))) {

        // Print header row
        writer.println(String.join(",", headerLabels));

        // Print all data rows
        for (String[] studentData : headerValues){
            writer.println(String.join(",", studentData);
        }
     }