判断字符串以多个指定的字符串开头

Question

如题，需求：
需要判断一串纯数字类型的字符串是否已 20 21 22 23 24开头
用什么方法可以
String.startWith("20,21,22,23,24") 这样测试了下 不行
求大哥指点下

Answer 1

用正则

         String regex = "2[0-4]\\d*";
        System.out.println(Pattern.matches(regex, "20"));
        System.out.println(Pattern.matches(regex, "201"));
        System.out.println(Pattern.matches(regex, "20a"));
        System.out.println(Pattern.matches(regex, "211"));
        System.out.println(Pattern.matches(regex, "221"));
        System.out.println(Pattern.matches(regex, "231"));
        System.out.println(Pattern.matches(regex, "241"));
        System.out.println(Pattern.matches(regex, "251"));