Checks whether the String contains only digit characters in Java

//from  w  w  w .ja va 2 s.com
public class Main {
  public static boolean isDigits(String str) {
      if (isEmpty(str)) {
          return false;
      }
      for (int i = 0; i < str.length(); i++) {
          if (!Character.isDigit(str.charAt(i))) {
              return false;
          }
      }
      return true;
  }
  public static boolean isEmpty(String str) {
      return str == null || str.length() == 0;
  }
  public static void main(String[] argv){
    System.out.println(isDigits("java2s.com") );
  }
}