code: public static Pattern hasAtLeast(final int n) {
      return new Pattern() {
        @Override public int match(CharSequence src, int begin, int end) {
          if ((begin + n) > end) return MISMATCH;
          else return n;
        }
        @Override public String toString() {
          return ".{" + n + ",}";
        }
      };
    }
docs: Returns a {@link Pattern} object that matches if the input has at least {@code n} characters left. Match length is
  {@code n} if succeed.