GPA

http://acm.hdu.edu.cn/game/entry/problem/show.php?chapterid=1&sectionid=2&problemid=19

这个程序学到了怎样用 BufferedReader 读一行数据。。以前都用的Scanner。。。。

//author:pz

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.text.DecimalFormat;

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        String s = in.readLine();
        while (s != null) {
            System.out.println(calGPA(s));
            s = in.readLine();
        }
    }

    private static String calGPA(String s) {
        DecimalFormat df = new DecimalFormat("0.00");
        double gpa = 0.0;
        for (int i = 0; i <= s.length() / 2; i++) {
            switch (s.charAt(2 * i)) {
            case 'A':
                gpa += 4;
                break;
            case 'B':
                gpa += 3;
                break;
            case 'C':
                gpa += 2;
                break;
            case 'D':
                ++gpa;
                break;
            case 'F':
                break;
            default:
                return "Unknown letter grade in input";
            }
        }
        gpa /= (s.length() / 2 + 1);
        return df.format(gpa);
    }
}