取出字符中的数字

String ln = "-100sdfer";
        String regEx = "[-]?[0-9]+";
        Pattern p = Pattern.compile(regEx);
        Matcher m = p.matcher(ln);
        if(m.find()){
            System.out.println(m.group());
        }else{
            System.out.println("没有找到。");
        }