How to use

connect

method

in

android.nfc.tech.MifareUltralight

  public String readTag(Tag tag) {
    MifareUltralight ultralight = MifareUltralight.get(tag);
    try {
      ultralight.connect();
      byte[] data = ultralight.readPages(4);
      return new String(data, Charset.forName("GB2312"));
    } catch (Exception e) {
    } finally {
      try {
        ultralight.close();
      } catch (Exception e) {
      }
    }
    return null;
  }
}

  public void writeTag(Tag tag) {
    MifareUltralight ultralight = MifareUltralight.get(tag);
    try {
      ultralight.connect();
      //写入八个汉字，从第五页开始写，中文需要转换成GB2312格式
      ultralight.writePage(4, "北京".getBytes(Charset.forName("GB2312")));
      ultralight.writePage(5, "上海".getBytes(Charset.forName("GB2312")));
      ultralight.writePage(6, "广州".getBytes(Charset.forName("GB2312")));
      ultralight.writePage(7, "天津".getBytes(Charset.forName("GB2312")));
      Toast.makeText(this, "写入成功", Toast.LENGTH_SHORT).show();
    } catch (Exception e) {
    } finally {
      try {
        ultralight.close();
      } catch (Exception e) {
      }
    }
  }
}

  throw new IllegalArgumentException("No Mifare Ultralight");
mifareUltralight.connect();