Difference between Java Post Request and Browser Post Request

I am trying to use api of one popular Russian social network. I am using OAuth via Java HttpUrlConnection. The problem is, when I post data after Java, I get a 401 response code. When I copy the request and paste it into the browser, I get a redirect to the URL containing the access token I need. This means that my post request is correct, but why, when I submit from Java, I get a 401 error? When I submit a request with the wrong password, I get 200. This means that the request is also correct.

private void getHomeAuth() throws Exception {
        String url = "https://oauth.vk.com/authorize?client_id=APP_ID&scope=friends&redirect_uri=https://oauth.vk.com/blank.html&display=page&v=5.34&response_type=token";

        URL oauth = new URL(url);
        HttpURLConnection connection = (HttpURLConnection) oauth.openConnection();
        connection.setRequestMethod("GET");
        connection.setRequestProperty("User-Agent", USER_AGENT);
        int responseCode = connection.getResponseCode();
        System.out.println("Response code: " + responseCode);

        BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
        String inputLine;
        StringBuilder response = new StringBuilder();

        while((inputLine = reader.readLine()) != null)
            response.append(inputLine + "\n");
        reader.close();
        PrintWriter writer = new PrintWriter("auth.html");
        writer.print(response);
        writer.close();
        parse();
        cookies = connection.getHeaderField("Set-Cookie");
        referer = connection.getURL().toString();
    }



private void postAuth() throws Exception {
        email = URLEncoder.encode("example@gmail.com", "UTF-8");
        password = "password";
        _origin = URLEncoder.encode(_origin, "UTF-8");
        String url = "https://login.vk.com/?act=login&soft=1";
        URL post = new URL(url);
        String urlParameters = "ip_h=" + ip_h + "&_origin=" + _origin + "&to=" + to + "&expire=" + expire + "&email=" + email + "&pass=" + password;
        HttpsURLConnection con = (HttpsURLConnection) post.openConnection();
        con.setRequestMethod("POST");
        con.setRequestProperty("User-Agent", USER_AGENT);
        con.setRequestProperty("Cookie", cookies);
        con.setDoOutput(true);
        DataOutputStream wr = new DataOutputStream(con.getOutputStream());
        wr.writeBytes(urlParameters);
        wr.flush();
        wr.close();
        int responseCode = con.getResponseCode();



        System.out.println("Sent post. Response code: " + responseCode + "\nRequest: " + post.toString() + urlParameters + "\nRequestMethod: " + con.getRequestMethod());

    }

      

        
        
        
      

    

I also tried to send this request via an addon in the browser and the result was correct. I got the access token from the redirect link.

Perhaps the problem is that something inside the request is wrong. I tried to track requests from a java application, but I failed.