Thursday, March 1, 2012

Android: JSONObject cannot be converted to JSONArray


I want to get data from php file to Android using JSON. This is my code:




....
HttpEntity e = r.getEntity();
String data = EntityUtils.toString(e);
JSONArray timeline = new JSONArray(data);
JSONObject last = timeline.getJSONObject(0);
return last;



When I debug the program there is JSONException on this line:




JSONObject last = timeline.getJSONObject(0);



data = {"a":1,"b":2,"c":3,"d":4,"e":5}



and the Exception is: "org.json.JSONException: Value {"d":4,"e":5,"b":2,"c":3,"a":1} of type org.json.JSONObject cannot be converted to JSONArray"

3 comments:

  1. In Json object are described using [].
    There you define an object with five attributes.

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  2. data = {"a":1,"b":2,"c":3,"d":4,"e":5}

    is already json array not json object.

    that's whay one by one get json array element.

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  3. The exception message is quite explicit and a look at the JSON syntax diagrams should be illustrative. The JSON string that your code received is:

    {"a":1,"b":2,"c":3,"d":4,"e":5}


    This string represents an object, not an array. An example of an array would be this:

    [1, 2, 3, 4, 5]


    or even this:

    [{"a":1,"b":2,"c":3,"d":4,"e":5}]


    Note that starting and closing brackets.

    I think that you will find that the exception location is slightly misleading. I don't know if it is a result of some sort of lazy initialization or something else, but I believe that the cause is actually this line:

    JSONArray timeline = new JSONArray(data);


    Since the data string represents a JSON object and not an array, this operation is clearly impossible.

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