import java.util.*;


public class Solution {
    /**
     * 
     * @param strs string字符串一维数组 the strings
     * @return string字符串
     */
    public String minString (String[] strs) {
        Arrays.sort(strs,(x,y) -> {
            String str1 = x + y;
            String str2 = y + x;
            for (int i = 0; i < str1.length(); i++) {
                if(str1.charAt(i) != str2.charAt(i)){
                    return str1.charAt(i) - str2.charAt(i);
                }
            }
            return 0;
        });
        StringBuffer sbr = new StringBuffer();
        for (int i = 0; i < strs.length; i++) {
            sbr.append(strs[i]);
        }
        return new String(sbr);
    }
}

直接对原String数组做个排序就好了,重点是把比较的两个字符串拼接起来后再比较