java - 如何在每 5 个数字后开始一个新行？

Question

我希望获得一些帮助来解决每五个数字后换行的问题。我将 1 到 90 之间的随机数放入数组列表中，然后将其写入文件中。 (稍后我想对列表和类似的所有内容进行排序，因此我使用 ArrayList 而不是立即将数字写入文件中。)

public class Lotto {

    static ArrayList<Integer> list = new ArrayList();


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


          randomNumber();
          fileReader();
    }

    public static void printHeader() {
        System.out.println("Week"
                + "|Numbers                           "
                + "\n"
                + "----+"
                + "-----------------------+");
    }

    public static void randomNumber() {
        int num;
        int n = 5;

      //  String str = String.valueOf(num);

        list = new ArrayList<>();
        try {


            FileWriter writer = new FileWriter("/Users/xyz/desktop/lotto2010.txt");
            BufferedWriter bw = new BufferedWriter(writer);

            for (int i = 1; i <= 260; i++) {
            double number = Math.random() * 90;

            num = (int) number;


            list.add(num);
            if((i % n) == 0) bw.newLine();

            }

            bw.write(list.toString());
            bw.close();

        } catch (IOException ex) {
            System.out.println("Couldn't write the file or directory doesn't exist" + ex.getMessage());
        }
    }

    public static void fileReader() throws IOException {


        FileReader fileReader = new FileReader("/Users/xyz/desktop/lotto2010.txt");
        String allText;
        try (PrintWriter writer = new PrintWriter("/Users/xyz/desktop/lotto2011.txt")) {
            BufferedReader br = new BufferedReader(fileReader);


            allText = br.readLine();

                writer.print(allText);            

        }
        System.out.println(allText);

    }
}

Answer 1

添加循环，检查i % 5 == 0，添加/n或bw.newLine()；