判断周几

        Scanner sc = new Scanner(System.in);
        List<String> ls = new ArrayList<String>();
        ls.add("Monday");
        ls.add("Tuesday");
        ls.add("Wednesday");
        ls.add("Thursday");
        ls.add("Friday");
        ls.add("Saturday");
        ls.add("Sunday");
        do {
            String day = sc.next();
            System.out.println("输入:" + day);
            int index = -1;    //记录是周几的index
            int count = 0;    //判断输入的字母能判断出多少符合条件的周几
            for (int i = 0; i < ls.size(); i++) {
                Pattern p = Pattern.compile("^" + day.toLowerCase());
                Matcher m = p.matcher(ls.get(i).toLowerCase());
                boolean b = m.find(); // 是否找到以输入值开头的
                if (b) {
                    index = i;  //记录下来周几的index
                    count++;
                }
            }
            if (count > 1) {
                System.out.println("输入字母不足以判断是周几,请重新输入...");
            } else if (count == 1) {
                System.out.println("输入的为:" + ls.get(index));
            } else {
                System.out.println("识别不了您输入的是周几");
            }
        } while (true);