title: POST with Android Retrofit
body: <p>I'm new to Android programming and working with Retrofit. I've done a bunch of research on this topic, but haven't been able to find a solution specific to my needs. I'm working with our API and trying to make a POST request. I successfully achieved this with the following non-Retrofit code:</p>
  
  <pre><code>    private class ProcessLogin extends AsyncTask&lt;Void, String, JSONObject&gt; {
      private ProgressDialog pDialog;
      String email,password;
  
      protected void onPreExecute() {
          super.onPreExecute();
          inputEmail = (EditText) findViewById(R.id.email);
          inputPassword = (EditText) findViewById(R.id.password);
          email = inputEmail.getText().toString();
          password = inputPassword.getText().toString();
          pDialog = new ProgressDialog(LoginActivity.this);
          pDialog.setTitle("Contacting Servers");
          pDialog.setMessage("Logging in ...");
          pDialog.setIndeterminate(false);
          pDialog.setCancelable(true);
          pDialog.show();
      }
  
      protected JSONObject doInBackground(Void... params) {
          HttpURLConnection connection;
          OutputStreamWriter request = null;
          URL url = null;   
          String response = null;         
          String parameters = "username="+email+"&amp;password="+password;  
          try
          {
              url = new URL("http://.../api/login");
              connection = (HttpURLConnection) url.openConnection();
              connection.setDoOutput(true);
              connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
              connection.setRequestMethod("POST");    
  
              request = new OutputStreamWriter(connection.getOutputStream());
              request.write(parameters);
              request.flush();
              request.close();            
              String line = "";               
              InputStreamReader isr = new InputStreamReader(connection.getInputStream());
              BufferedReader reader = new BufferedReader(isr);
              StringBuilder sb = new StringBuilder();
              while ((line = reader.readLine()) != null)
              {
                  sb.append(line + "\n");
              }
              // Response from server after login process will be stored in response variable.                
              response = sb.toString();
              // You can perform UI operations here
              isr.close();
              reader.close();
          }
          catch(IOException e)
          {
              // Error
          }
          System.out.println(response);
          JSONObject jObj = null;        
          // Try to parse the string to a JSON Object
          try {
              jObj = new JSONObject(response);
          } catch (JSONException e) {
              Log.e("JSON Parser", "Error parsing data " + e.toString());
          }
  
          // Return the JSONObject
          return jObj;
      }
  
      protected void onPostExecute(JSONObject json) {
          String status = (String) json.optJSONArray("users").optJSONObject(0).optJSONObject("user").optString("login");
          pDialog.dismiss();
          if (status.equals("Failed")) {
              loginMessage.setText("Login Failed");   
          }
          else if (status.equals("Success")) {
              loginMessage.setText("Success!");   
              startActivity(new Intent(getApplicationContext(), DActivity.class));
          }
  
      }
  }
  </code></pre>
  
  <p>Now, I'm trying to get the same results using Retrofit, but I'm not sure how to get the JSON back from our API using Callbacks (I'm assuming this call should happen asynchronously?):   </p>
  
  <p>I've made an interface with the following method:</p>
  
  <pre><code>    @FormUrlEncoded
  @POST("/login")
  public void login(@Field("username") String username, @Field("password") String password, Callback&lt;JSONObject&gt; callback);
  </code></pre>
  
  <p>And instantiated the RestAdapter, etc in my Activity's onCreate method. When the user presses the "login" button (after entering their username and password), the following is called inside the button's onClick method:</p>
  
  <pre><code>    service.login(email, password, new Callback&lt;JSONObject&gt;() { 
              @Override
              public void failure(final RetrofitError error) {
                  android.util.Log.i("example", "Error, body: " + error.getBody().toString());
              }
              @Override
              public void success(JSONObject arg0, Response arg1) {
  
              }
          }
          );
  </code></pre>
  
  <p>This is not working as intended however, and I really don't think I'm approaching this correctly. I want to be able to make a POST to our server, which sends back a block of JSON formatted data about that user. If anyone could point me in the right direction, that would be really appreciated. Thank you in advance</p>