Java课后题第十二章：12.23（处理文本中的分数）

1、正则式判断分数

if (s1.matches("-?[0-9]+.?[0-9]*")) 

2、定界符分隔（空格  ：，）

Scanner input = new Scanner(file).useDelimiter("[ :,]");

3、示例

public class Test1 {
    public static void main(String[] args) throws Exception {
        File file = new File("file1.txt"); //relative path
        Scanner input = new Scanner(file).useDelimiter("[ :,]");
        double sum = 0.0;
        int count = 0;
        while (input.hasNext()) {
            String s1 = input.next();
            if (s1.matches("-?[0-9]+.?[0-9]*")) {
                sum += Double.parseDouble(s1);
                System.out.println("is true");
                count++;
            }
        }
        input.close();
        System.out.println("scores' sum is " + sum + "nand the average: " + sum / count);
    }
}