Java Http request on api.stackexchange with json response

Question

I'm trying to use the api-stackexchange with java but when I do the request and try to parse the response with a json parser I have an error.

public ArrayList<Question> readJsonStream(InputStream in) throws IOException {
    JsonReader reader = new JsonReader(new InputStreamReader(in, "UTF-8"));
    reader.setLenient(true);
    try {
        System.out.println(reader.nextString()); // � special character
                    return readItem(reader);
    } finally {
        reader.close();
    }
}

public ArrayList<Question> readItem(JsonReader reader) throws IOException {
    ArrayList<Question> questions = new ArrayList<Question>();

    reader.beginObject();

    while (reader.hasNext()) {
        System.out.println("here");//not print the error is before
        String name = reader.nextName();
        if (name.equals("items")) {
            questions = readQuestionsArray(reader);
        }
    }
    reader.endObject();
    return questions;
}

public final static void main(String[] args) throws Exception {

    URIBuilder builder = new URIBuilder();
    builder.setScheme("http").setHost("api.stackexchange.com").setPath("/2.0/search")
    .setParameter("site", "stackoverflow")
    .setParameter("intitle" ,"workaround")
    .setParameter("tagged","javascript");
    URI uri = builder.build();

    String surl = fixEncoding(uri.toString()+"&filter=!)QWRa9I-CAn0PqgUwq7)DVTM");
    System.out.println(surl);
    Test t = new Test();
    try {
        URL url = new URL(surl);
        t.readJsonStream(url.openStream());

    } catch (IOException e) {
        e.printStackTrace();
    }

}

And the error is:

com.google.gson.stream.MalformedJsonException: Expected literal value at line 1 column 19

Here is an example of the Json :

        {
          "items": [
            {
              "question_id": 10842231,
              "score": 0,
              "title": "How to push oath token to LocalStorage or LocalSession and listen to the Storage Event? (SoundCloud Php/JS bug workaround)",
              "tags": [
                "javascript",
                "javascript-events",
                "local-storage",
                "soundcloud"
              ],
              "answers": [
                {
                  "question_id": 10842231,
                  "answer_id": 10857488,
                  "score": 0,
                  "is_accepted": false
                }
              ],
              "link": "http://stackoverflow.com/questions/10842231/how-to-push-oath-token-to-localstorage-or-localsession-and-listen-to-the-storage",
              "is_answered": false
            },...

Here is the URL of the request:

https://api.stackexchange.com/2.0/search?tagged=javascript&intitle=workaround&site=stackoverflow&filter=!)QWRa9I-CAn0PqgUwq7)DVTM

So what's the problem? Is the Json really malformed? Or did I do something not right?

Thanks, Anthony

Edit:

I'm now sure that the problem come to the request, I paste the response of the request via a browser in a text file that I host in a server Apache and it works fine. I am abble to parse the Json of the response.

Jesse Wilson · Accepted Answer · 2012-06-05 05:00:44Z

2

Change this code:

    if (name.equals("items")) {
        questions = readQuestionsArray(reader);
    }

to this code:

    if (name.equals("items")) {
        questions = readQuestionsArray(reader);
    } else {
        reader.skipValue();
    }

Otherwise you end up calling nextName() twice in a row, which is invalid.

answered Jun 5, 2012 at 5:00

Jesse Wilson

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5 Comments

Jesse Wilson Over a year ago

By the way, I'm one of the Gson maintainers and you caused me to panic quite a bit on this question. It took me a good ten minutes to figure out what the problem is!

AnthonyMaia Over a year ago

Thanks, but this don't resolve my problem. I think the problem is on the http request. The response is maybe not a well formed Json. Why the reader.nextString() give me special characters and not the real next String.

Jesse Wilson Over a year ago

Is it a BOM? blog.publicobject.com/2010/08/…

AnthonyMaia Over a year ago

How can I know if it's a BOM? I can't use the method in the link my inputStream is not mark supported.

AnthonyMaia Over a year ago

Thank you @JesseWilson to bring me on the good way with the encoding thing.

thejartender · Accepted Answer · 2012-06-10 12:21:02Z

The data in the response is compressed with the deflate algorithm. So, I encapsulated the InputStream with a GZIPInputStream:

public final static void main(String[] args) throws Exception {
    URIBuilder builder = new URIBuilder();
builder.setScheme("http").setHost("api.stackexchange.com").
        setPath("/2.0/search").
        setParameter("site", "stackoverflow").
        setParameter("intitle" ,"workaround").
        setParameter("tagged","javascript");
URI uri = builder.build();
ArrayList<Question> q =null;
String result = "";
String surl = fixEncoding(uri.toString()+"&filter=!)QWRa9I-CAn0PqgUwq7)DVTM");
System.out.println(surl);
Test t = new Test();

    try {
    URL url = new URL(surl);
    q = t.readJsonStream(new GZIPInputStream(url.openStream()));        
} 

    catch (IOException e) {
        e.printStackTrace();
    }

    System.out.println(result);

    for (Question question : q) {
        System.out.println(question.title);
    }
}

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