Android：如何从Volley OnRequest StringRequest方法返回JSONObject

Question

i need to pass the response string by assigning value to the string data to another method out side the OnResponse() scpoe so that i can return a JSONObject from it by calling that method but it always returns null

all i need is to get JSONObject from Volley stringrequest as the response is a xml "

<?xml version="1.0" encoding="utf-8"?>
<string xmlns="http://tempuri.org/">........</string>

Here is my code

static String data;

private  void driverByIdStringRequest(int ID,final Context context){
        RequestQueue queue = VolleySingleton.getInstance(context.getApplicationContext()).getRequestQueue();
        // Request a string response from the provided URL.
        StringRequest stringRequest = new StringRequest(Request.Method.GET, url+ID,
                new Response.Listener<String>() {
                    @Override
                    public void onResponse(String response) {
                        response = response.replaceAll("<?xml version=\"1.0\" encoding=\"utf-8\"?>", "");
                        response = response.replaceAll("<string xmlns=\"http://tempuri.org/\">", "");
                        response = response.replaceAll("</string>", "");
                        String data = response.substring(40);
                    }
                }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                Log.d("Error : ", error.toString());
            }
        });
        VolleySingleton.getInstance(context).addToRequestQueue(stringRequest);
    }


public JSONObject GetDriverById(int ID,Context context){
    driverByIdStringRequest(ID, context);
    JSONObject json = JSONObject(data);
    return json;
}

Answer 1

The best maintainable way to do it is first to parse you XML with a Parser.

Just follow this tutorial on the official doc.

Once you got your string you just have to do

JSONObject mainObject = new JSONObject(Your_Sring_data);

(Android studio will prompt you to put the correct try/catch around the JSON creation.)

Answer 2

If the String response from your StringRequest always has the following format:

<?xml version="1.0" encoding="utf-8"?>
<string xmlns="http://tempuri.org/">........</string>

in which ........ is the JSONObject you want to get, I suggest that you process the String reponse like the following way:

...
String jsonString = stringResponse;

jsonString = jsonString.replace("<?xml version=\"1.0\" encoding=\"utf-8\"?>"," ");
jsonString = jsonString.replace("<string xmlns=\"tempuri.org/\">"," ");
jsonString = jsonString.replace("</string>"," ");
try {
    JSONObject jsonObject = new JSONObject(jsonString);
} catch (JSONException e) {
    e.printStackTrace();
}
...

Back to your code, data of course NULL because JSONObject json = JSONObject(data); called before onResponse inside the Request called. I suggest that you refer to my answer at the following question for your issue:

Android: How to return async JSONObject from method using Volley?

Hope this helps!