java 通过正则表达式判断字符串是否以数字开头

       String str="123123ssdfssss";
       Pattern pattern = Pattern.compile("^(\\d+)(.*)");
        Matcher matcher = pattern.matcher(str);
        if (matcher.matches()) {
            System.out.println(matcher.group(1));// =123123
            System.out.println(matcher.group(2));// =ssdfssss
        }