"笨办法"反复遍历,找出最终答案

import java.util.*;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(sc.hasNextLine()){
            String str = sc.nextLine() + "a"; //防止结尾以数字结尾
            StringBuilder sb = new StringBuilder();
            ArrayList<String> list = new ArrayList<>();

            for(int i = 0;i < str.length();i++){ //将字串存储进List当中
                if(str.charAt(i) >= '0'&&str.charAt(i) <= '9'){
                    sb.append(str.charAt(i));
                }else if(sb.length() != 0){
                    list.add(sb.toString());
                    sb.setLength(0);
                }
            }
            int max = 0;
            sb.setLength(0);
            for(int i = 0;i < list.size();i++){  //遍历出长度最大值
                max = Math.max(max,list.get(i).length());
            }
            for(int i = 0;i < list.size();i++){  //查找长度最长的字串并拼接
                if(list.get(i).length() == max) sb.append(list.get(i));
            }
            System.out.println(sb.toString() + "," + max);
        }
        sc.close();
    }
}