Question

I am a very beginner about JSON…

How can I get the value of “3037904” from the following JSON Object in Java program?

{“query”:{“pages”:{“3037904”:{“pageid”:3037904,”ns”:0,”title”:”Kempinski”,
“categories”:[{“ns”:14,”title”:”Category:Companies established in 1897″},{“ns”:14,”title”:”Category:Hotel chains”},{“ns”:14,”title”:”Category:Kempinski Hotels”}]}}}}

I tried to

JSONObject query = json.getJSONObject("query");
int pages = query.getInt("pages");

But it takes

"{"3037904":{"pageid":3037904,"ns":0,"title":"Kempinski",
"categories":[{"ns":14,"title":"Category:Companies established in 1897"},{"ns":14,"title":"Category:Hotel chains"},{"ns":14,"title":"Category:Kempinski Hotels"}]}}}}", 

not only “3037904”.

Answer 1

You’ll need to do a little more work with your JSONObject.

In this answer I’ll assume that you want to get at that pageid value.

Let’s only assume the existence of pageid in the nesting – at a specific level:

// "query" is the top-level object: 
JSONObject query = json.getJSONObject("query");
// "pages" is a field of "query"
JSONObject pages = query.getJSONObject("pages");

// these will hold the object with the value that you want, and that value:
JSONObject nestedObject = null;
int pageId = 0;

// these are the property names in the "pages" object:
String[] keys = pages.getNames(pages);

// iterate over the keys in the "pages" object, looks for JSONObjects:
for (int i = 0; i < keys.length; i++)
{
    try
    {
        nestedObject = pages.getJSONObject(keys[i]);
        // only consider objects with a "pageid" key, stop at the first one:
        if (nestedObject.has("pageid"))
            break;
    }
    catch (JSONException je)
    { ; }
}

if (nestedObject != null)
   pageId = nestedObject.getInt("pageid");

Your JSON input seems peculiar in that the first nested object has a pages field, that contains another object. The name in plural, pages, and the nested object – which duplicates the key containing the object as a pageid key within the object – suggests that pages should be an array of multiple such objects.