字符串统一长度：分割补零

JAVA 题有点问题，常规写过不了，要多加一个while，可能是例子为一组，后台测试要输入很多组。

import java.util.HashMap;
import java.util.Scanner;
import java.util.LinkedList;
public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(sc.hasNext()){
            int n = Integer.valueOf(sc.nextLine());
            for (int i = 0; i <n; i++){
                String str = sc.nextLine();
                helper(str);
            }
        }
    }
    private static void helper(String s){
        if (s == null) return;
        int a = 0;
        if (s.length() % 8 != 0) a = 8 - s.length()%8;
        while(a>0) {
            s += "0";
            a--;
        }
        /*
        int a = s.length() % 8;
        StringBuilder sb = new StringBuilder(s);
        if(a != 0){
            for(int i = 8-a ; i > 0 ; i--){
                sb.append('0');
            }
        }
        s = sb.toString();
        */

        for (int i = 0; i < s.length(); i+=8){
            System.out.println(s.substring(i, i+8));
        }
    }
}