Java双重循环实现任意字符串中提取数字子串

public class Test2{

 public static void main(String[] args) {

  String s = "211ahn678rh2kkk07312n3e12w4";

  int begin = 0;

  outer:for(;begin<s.length();){

   if(!(s.charAt(begin)>=48 && s.charAt(begin)<=57)){

    begin++;

    continue;

   }

   int end = begin;

   for(;end<s.length();){

    if(!(s.charAt(end)>=48 && s.charAt(end)<=57)){

     System.out.println(s.substring(begin,end));

     begin = end;

     break;

    }else{

     end++;

     if(end == s.length()){

      System.out.println(s.substring(begin));

      break outer;

     }else{

      continue;

     }

    }

   }

  }

 }

}