Java Data Type - 如何检查字符串是否包含我没有列出的字符

import java.util.regex.Pattern;

public class Main {
  private static final Pattern VALID_STR = Pattern.compile("(?i)[a-z0-9]+");

  public static boolean isValidStr(String s) {
    return VALID_STR.matcher(s).matches();
  }

  public static void main(String[] args) {
    System.out.println(isValidStr("abc12d")); // true
    System.out.println(isValidStr("abc ")); // false
  }
}