Android中的cURL命令（miniflux）

Question

我需要转换这个miniflux cURL命令：

curl \
-u "demo:swB3/nSo1CB1X2F" \
-d '{"jsonrpc": "2.0", "method": "feed.list", "id": 1}' \
https://demo.miniflux.net/jsonrpc.php  

成为可用的java（android）代码，用于我的android应用程序。这是我的代码：

public static void post() {
    try {
        Log log = null;
        String url = "https://demo.miniflux.net/jsonrpc.php ";

        URL obj = new URL(url);
        HttpURLConnection conn = (HttpURLConnection) obj.openConnection();

        conn.setRequestProperty("Content-Type", "application/json");
        conn.setDoOutput(true);

        conn.setRequestMethod("POST");

        String userpass = "demo" + ":" + "swB3/nSo1CB1X2F";
        String basicAuth = "Basic " + javax.xml.bind.DatatypeConverter.printBase64Binary(userpass.getBytes("UTF-8"));
        conn.setRequestProperty ("Authorization", basicAuth);

        String data =  "{\"jsonrpc\": \"2.0\", \"method\": \"feed.list\", \"id\": 1}";
        OutputStreamWriter out = new OutputStreamWriter(conn.getOutputStream());
        out.write(data);
        out.close();

        new InputStreamReader(conn.getInputStream());*/

    } catch (Exception e) {
        Log log1 = null;
        log1.v("Exception>>>>>>","Exception Thrown O_O");
    }

}

此代码抛出异常。关于miniflux卷曲命令的文档可以在这里找到：https://miniflux.net/documentation/json-rpc-api我做错了什么？感谢。