JSON Object Returns Null

Question

I have a very strange error when trying to get a number from a JSON API; the object seems to be null, although the URL (and code) should be correct.

org.json.JSONException: JSONObject["success"] not found.

I have tried printing out the JSONObject, and it gives me this:

{}

Here is my code:

    try{
        String url = "https://qrng.anu.edu.au/API/jsonI.php?length=1&type=uint16";
        JSONObject jsonObject = new JSONObject(new URL(url).openStream());
        String resultType = jsonObject.getString("success");
        if(resultType.equalsIgnoreCase("true")){
            JSONArray jsonArray = jsonObject.getJSONArray("data");
            int number = jsonArray.getInt(0);
           //do stuff with number
        }
        else{
            //unsuccessful
        }
    }
    catch(Exception e){
       //handle catch
    }

Which JSON library are you using? I'm asking because I can't seem to find a library with a JSONObject constructor that takes an InputStream as a parameter. — Andreas
– Andreas, Commented Oct 30, 2016 at 15:38
@Andreas Quite honestly I'm not too sure, but the imports I am using are import org.json.JSONArray; import org.json.JSONObject; — Arraying
– Arraying, Commented Oct 30, 2016 at 15:39
@Arraying No additional Libraries? Are these JDK classes? Seems wierd to me — n247s
– n247s, Commented Oct 30, 2016 at 15:41
Seems you're calling this constructor: JSONObject(java.lang.Object bean). Since the InputStream returned by openStream() (which you need to close too, or you have a memory leak), and since it has no "bean" getters, you end up with an empty JSON object. In short, you're calling it wrong, i.e. not actually giving it the JSON string. — Andreas
– Andreas, Commented Oct 30, 2016 at 15:42
@n247s Well I haven't manually added anything, it would seem as if they are JDK classes, but I do have Apache Commons added to my dependencies. — Arraying
– Arraying, Commented Oct 30, 2016 at 15:42

Derrick · Accepted Answer · 2016-10-30 16:06:52Z

1

@Andreas is right, add this piece of code in your try block to convert input stream into a json string -

InputStream is = new URL(url).openStream();
int ch;
StringBuilder sb = new StringBuilder();
while((ch = is.read()) != -1)
sb.append((char)ch);            
JSONObject jsonObject = new JSONObject(sb.toString());

answered Oct 30, 2016 at 16:06

Derrick

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3 Comments

Arraying Over a year ago

I've used the following yet it still gives me the same error:

Derrick Over a year ago

make sure to pass sb.toString() in your JsonObject constructor

Arraying Over a year ago

Still doesn't work, I even copied and pasted the code, still errors.

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