import java.util.*;
class Solution {
public String solution(String new_id) {
new_id = new_id.toLowerCase(Locale.ROOT)
.replaceAll("[^a-z0-9-_.]", "")
.replaceAll("\\.{2,}", "\\.")
.replaceAll("^\\.|\\.$", "");
if(new_id.equals("")) new_id = "a";
if(new_id.length() >= 16) {
new_id = new_id.substring(0, 15);
new_id = new_id.replaceAll("\\.$", "");
}
if(new_id.length() <= 2){
char curStr = new_id.charAt(new_id.length() - 1);
StringBuilder str = new StringBuilder();
str.append(new_id);
while (str.length() < 3){
str.append(curStr);
}
new_id = str.toString();
}
return new_id;
}
}
이건 뭐 정규식쓰는 문제라서 그냥 정규식연습했다고 생각