(JAVA) 문자열 다루기 기본

class Solution {
  public boolean solution(String s) {
      boolean answer = false;
      int check = s.length();
      if(check==4||check==6){
          if(s.matches("^\\d+$")){
              return true;
          }
      }
      return answer;
    }
}

-----------------

class Solution {
  public boolean solution(String s) {
      if(s.length() == 4 || s.length() == 6){
          try{
              int x = Integer.parseInt(s);
              return true;
          } catch(NumberFormatException e){
              return false;
          }
      }
      else return false;
  }
}
---------------
import java.util.*;
class Solution {
  public boolean solution(String s) {
        if (s.length() == 4 || s.length() == 6) return s.matches("(^[0-9]*$)");
        return false;
  }
}
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