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

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

        // 1. 使用 try-with-resources，自动关闭流
        try (BufferedReader br = new BufferedReader(new FileReader(filePath))) {
            String line;
            while ((line = br.readLine()) != null) {
                // 去掉前后空格，跳过空行
                line = line.trim();
                if (line.isEmpty()) {
                    continue;
                }

                // 2. 处理数字格式错误
                try {
                    int score = Integer.parseInt(line);
                    sum += score;
                    count++;
                } catch (NumberFormatException e) {
                    System.err.println("⚠️ 警告：跳过无效成绩行（非数字内容）：" + line);
                }
            }

            // 计算并输出结果
            if (count == 0) {
                System.out.println("ℹ️ 提示：文件中没有有效成绩数据");
            } else {
                double average = (double) sum / count;
                System.out.printf("✅ 平均分：%.2f%n", average);
            }

        } catch (IOException e) {
            // 3. 处理文件不存在、读取错误等IO异常
            System.err.println("❌ 文件操作失败：" + e.getMessage());
            e.printStackTrace();
        }
    }
}