java/W7/ScoreAverage.java

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

public class ScoreAverage {
    public static void main(String[] args) {
        String fileName = "scores.txt";
        int sum = 0;
        int count = 0;

        // 1. 使用 try-with-resources 自动关闭流，确保资源释放
        try (BufferedReader br = new BufferedReader(new FileReader(fileName))) {
            String line;

            // 2. 逐行读取文件
            while ((line = br.readLine()) != null) {
                // 跳过空行，避免 NumberFormatException
                line = line.trim();
                if (line.isEmpty()) {
                    continue;
                }

                try {
                    // 3. 转换为整数并累加
                    int score = Integer.parseInt(line);
                    sum += score;
                    count++;
                } catch (NumberFormatException e) {
                    // 处理数字格式错误
                    System.err.println("警告：无法将内容 '" + line + "' 转换为整数，已跳过。");
                }
            }

            // 4. 计算并输出平均分
            if (count > 0) {
                double average = (double) sum / count;
                System.out.println("成绩文件读取完成。");
                System.out.println("总分：" + sum);
                System.out.println("人数：" + count);
                System.out.printf("平均分：%.2f%n", average);
            } else {
                System.out.println("文件中没有有效的成绩数据。");
            }

        } catch (IOException e) {
            // 处理文件不存在、读取错误等IO异常
            System.err.println("读取文件时发生错误：" + e.getMessage());
            e.printStackTrace();
        }
    }
}