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。。。。

 1 //author:pz
 2 
 3 import java.io.BufferedReader;
 4 import java.io.IOException;
 5 import java.io.InputStreamReader;
 6 import java.text.DecimalFormat;
 7 
 8 public class Main {
 9     public static void main(String[] args) throws IOException {
10         BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
11         String s = in.readLine();
12         while (s != null) {
13             System.out.println(calGPA(s));
14             s = in.readLine();
15         }
16     }
17 
18     private static String calGPA(String s) {
19         DecimalFormat df = new DecimalFormat("0.00");
20         double gpa = 0.0;
21         for (int i = 0; i <= s.length() / 2; i++) {
22             switch (s.charAt(2 * i)) {
23             case 'A':
24                 gpa += 4;
25                 break;
26             case 'B':
27                 gpa += 3;
28                 break;
29             case 'C':
30                 gpa += 2;
31                 break;
32             case 'D':
33                 ++gpa;
34                 break;
35             case 'F':
36                 break;
37             default:
38                 return "Unknown letter grade in input";
39             }
40         }
41         gpa /= (s.length() / 2 + 1);
42         return df.format(gpa);
43     }
44 }