java/w7/AverageScoreAfter.java

package w7;

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

public class AverageScoreAfter {
    public static void main(String[] args) {
        int sum = 0, count = 0;
        try (BufferedReader br = new BufferedReader(new FileReader("scores.txt"))) {
            String line;
            while ((line = br.readLine()) != null) {
                line = line.trim();
                if (line.isEmpty()) continue;
                try {
                    sum += Integer.parseInt(line);
                    count++;
                } catch (NumberFormatException e) {
                    System.err.println("忽略无效数字：" + line);
                }
            }
        } catch (FileNotFoundException e) {
            System.err.println("文件不存在");
            return;
        } catch (IOException e) {
            System.err.println("读取错误");
            return;
        }
        if (count == 0) System.err.println("无有效成绩");
        else System.out.printf("平均分：%.2f%n", (double) sum / count);
    }
}