关于JAVA File的问题！跪求大神教我，顺便解释那个代码的意思

Question

Answer 1

以下是代码片段，你可以参考下

package test;

import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;

public class JavaIo {
    // Write a program to create a file named integerFile.txt if it does not exists. Write 100
    // integers
    // created randomly into the file using text I/O. The random integers should be in the range 0
    // to
    // 100(including 0 and 100). Integers should be separated by spaces in the file. Read the data
    // back from the file and display the data in increasing order.
    // 解题：用java IO流创建一个integerFile.txt的文本文件，如果这个文件不存在要创建它。文件内容要写入100个随机数，
    // 随机数的范围在0到100，包含0和100。然后读取文件，按照升序展示这个数据
    public static void main(String[] args) {
        // 文件全路径
        String fileName = "d:\\integerFile.txt";
        try {
            File file = new File(fileName);
            // 文件存在删除它，创建新的
            file.deleteOnExit();
            if (!file.exists()) {
                // 创建文件
                file.createNewFile();
            }
            // 100个空格分隔的随机数
            StringBuffer sb = new StringBuffer();
            for (int i = 0; i < 100; i++) {
                int number = (int) (Math.random() * 101);
                sb.append(number + " ");
            }
            FileWriter fw = new FileWriter(file);
            System.out.println("写入的数据="+sb.toString());
            // 写数据
            fw.write(sb.toString());
            // 刷新缓存区
            fw.flush();
            // 关闭文件流
            fw.close();
            System.out.println("写入文件成功。。。");
            // 读取文件
            System.out.println("读取的数据");
            FileReader fr = new FileReader(file);
            char[] buf = new char[(int) file.length()];
            int len;
            StringBuffer readSb = new StringBuffer();
            while ((len = fr.read(buf)) != -1) {
                readSb.append(new String(buf, 0, len));
            }
            fr.close();
            // 冒泡排序算法
            String[] numbers = readSb.toString().split(" ");
            int i, j;
            for (i = 0; i < numbers.length; i++) {
                for (j = 0; j < numbers.length - 1 - i; j++) {
                    // 按照升序排列
                    if (Integer.parseInt(numbers[j]) > Integer.parseInt(numbers[j + 1])) {
                        String temp = numbers[j];
                        numbers[j] = numbers[j + 1];
                        numbers[j + 1] = temp;
                    }
                }
            }
            // 展示数据
            for (int a = 0; a < numbers.length; a++) {
                System.out.print(numbers[a]+" ");
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}