CheckHatenaID.java

import java.util.regex.Pattern;
import java.util.regex.Matcher;

public class CheckHatenaID {
  
  public static void main (String[] args) {
    String hatenaID = "shogonir";
    Pattern p = Pattern.compile("[a-zA-Z][a-zA-Z0-9_\\-]{1,30}[a-zA-Z0-9]");
    Matcher m = p.matcher(hatenaID);
    boolean f = m.matches();
    System.out.println(String.valueOf(f));
  }
  
}