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Java/Android JSONArray inside JSONObject returning null

I'm developing an app for android that communicates with a server and receives JSON responses from it. Recently I changed the responses structure to contain more information about the requests.
Initially my responses where just the response from a mysqli_query encoded to JSON by the php function json_encode, and looked like this:
[
{"id":"31","description":"Hello"},
{"id":"32","description":"World"},
]
And to retrieve the objects, I would just create a new JSONArray object by calling my_json_array=new JSONArray(response) and iterate over it.
But now, my new responses contain extra data, like this:
{
"error":false,
"idCode":0,
"message":[
{
"id":"32",
"description":"Hello"
},
{
"id":"31",
"description":"World"
}
]
}
So now, as far as I understand, I need to convert this response to a JSONObject, and then extract the message as a JSONarray object by calling my_json_object.getJSONArray("message");.
I can extract the data from the "error" and the "idCode" fields normally, but when I try to extract the JSONArray from "message" it returns null, and no exceptions are thrown except for the NullPointerException.
I've validated the JSON string here, escaped the characters that could be problematic for java like the double quotes, removed uppercases, written the response as a single line, removed the double quotes surrounding the "id" value, used single quotes instead of double quotes, used harcoded string instead of the response from the server, checked the unicode representation of the string to see if contains any invalid characters (and it looks like it doesn't) and I don't know what else to do. Something to notice: the method toString() on the object returns the string "null", and based on the toString() method of the JSONObjects, it seems like the problem comes from the JSONStringer library, and going deeper on the classes it looks like the exception that there is a nesting problem, but I can't find any problem in my JSON string.
The important part of the code:
public String getResponse(){
web_helper.sendRequest();
//everything fine over here
return web_helper.getResponse();
}
public void printData(){ throws JSONExpection
JSONObject my_json_object=new JSONObject(getResponse());
System.out.println("error: "+my_json_object.getBoolean("error"));
System.out.println("idCode: "+my_json_object.getInt("idCode"));
JSONArray my_json_array=my_json_object.getJSONArray("message");
//not sure if the next part works because my_json_array is null
for(int i=0; i<my_json_array.length(); i++){
JSONObject obj=my_json_array.getJSONObject(i);
System.out.println("id: "+obj.getInt("id"));
System.out.println("description: "+obj.getString("description"));
}
}
Any help is appreciated, thank you in advance!.

JSON Object to generic ParseFile Object, issue

I have run in to an issue, while converting my iOS app to android.
The database is structured such that there are "stations", these stations can have multiple images attached, in the parse database, the images are an array of imagePointers.
When i wanted to get the images out in iOS here is what i did:
stations = object in this case
// Get a single image
if ([[object objectForKey:#"imagePointers"] objectAtIndex:0] != [NSNull null]) {
PFFile *imageFile = [[[object objectForKey:#"imagePointers"] objectAtIndex:0] objectForKey:#"image"];
cell.coverImageView.file = imageFile;
[cell.coverImageView loadInBackground];
}
Its pretty simple, i just lift the imagePointers array and get objectAtIndex0, then i cast it to a parse file.
But i can't do this in android, here is what i have atm:
JSONArray imagePointers = thisStation.getJSONArray("imagePointers");
try {
JSONObject indexImage = imagePointers.getJSONObject(0);
} catch ( Exception e ) {
JSONObject indexImage = null;
}
Here i get the object at index 0 as a JSONObject, i cannot use this in a ParseFile Object, since i need to cast it as a generic type ParseFile.
How do i do this? Or is my approach completely incorrect?

Fixed it by avoiding casting to JSON, apparently there is a getList method
// Get parse Image as index image
ParseObject thisStation = stationItems.get(position);
List<ParseObject>imagePointers = thisStation.getList("imagePointers");
ParseFile image = imagePointers.get(0).getParseFile("image");
thumbnail.setParseFile(image);
thumbnail.loadInBackground();

I had the same issue for almost 2 days but finally I solved it by the getList method!
Now all you gotta do is use getList instead of getJSONObject or getJSONArray or whatever, because when you use them you will not be able to use the getParseFile for any of those believe me.
But instead you can do something like:
val obj = parseObject.getList("listname")
val file = obj[0].getParseFile("image")
Now, I don't remember how the syntex is or so but the key here is to use the getList method if you want to get list of all images you saved in a Back4app Parse JSONArray.
Hope you found it helpful.
Goodluck

How to write multiple records to JSON in file on Java

I need to write multiple json in one file, the problem is that every time that inserts inserted as follows:
{"1":"{\"id\":\"1\"}"**}{**"2":"{\"id\":\"2\"}"**}{**"3":"{\"id\":\"3\"}"}
and I need the chain follows to that can be read for JSON:
{"1":"{\"id\":\"1\"}"**,**"2":"{\"id\":\"2\"}"**,**"3":"{\"id\":\"3\"}"}
my code is:
public void writeMci(String mci, String nombreMci) throws Exception{
FileReadWrite a=new FileReadWrite();
JSONObject vjo = new JSONObject();
vjo.put(nombreMci, mci);
try {
BufferedWriter write=new BufferedWriter(new FileWriter("c:\\JSON.json", true));
write.write(vjo.toString());
write.flush();
write.close();
} catch (IOException e) {
//manejar error
}
System.out.print(vjo);
}

The line you want
{"1":"{\"id\":\"1\"}"**,**"2":"{\"id\":\"2\"}"**,**"3":"{\"id\":\"3\"}"}
isn't legal either, I assume you mean (at least) something like this:
{"1":"{\"id\":\"1\"}","2":"{\"id\":\"2\"}","3":"{\"id\":\"3\"}"}
Note that this is not a JSON array, it's an object with string fields respectively called 1 2 and 3 that happen to contain JSON syntaxed string values. Although not illegal, it's highly questionable you actually want that
Now, could it be that you mean
{"1":{"id":"1"},"2":{"id":"2"},"3":{"id":"3"}}
Still an object but with object fields respectively called 1 2 and 3, where the object has just 1 field called id? Anyways (disclaimer: not an org.json library user myself - see below - so not giving any guarantees wrt the accuracy of the code :) ) :
// Create the outer container
JSONObject outer = new JSONObject();
// Create a container for the first contained object
JSONObject inner1 = new JSONObject();
inner1.put("id",1);
// and add that to outer
outer.put("1",inner1);
// Create a container for the second contained object
JSONObject inner2 = new JSONObject();
inner2.put("id",2);
// and add to outer as well
outer.put("2",inner2);
// Create a container for the third contained object
JSONObject inner3 = new JSONObject();
inner3.put("id",3);
// and add that to outer
outer.put("3",inner3);
// at this point
outer.toString()
// should return the JSON String from my last step.
if you actually want it to be an array, you need to put the objects in a JSONArray, and wrap that array as a named field inside an object. The end result will look more or less like this:
{"data": [{"id":"1"},{"id":"2"},{"id":"3"}]}
Code for the inner objects is the same as above, but there's a new layer (the array) between the inner and outer object:
JSONArray middle = new JSONArray();
...
middle.add(inner1);
...
middle.add(inner2);
...
middle.add(inner3);
...
outer.put("data",middle);
Still not sure if that's what you actually want, but I think it's a first step towards a solution. That being said, I would recommend you to switch to a nicer JSON Java library than the one from json.org you are apparently using. Look here for some feedback on different libraries that are available, for my projects I've been using Jackson since quite some time now and I'm very happy with it, but the SO question I linked to talks about several other, excellent alternatives.

You should write both objects, as below:
write.write(vjo.toString());
write.newLine();
write.write(conb.toString());
write.newline();
write.flush();
write.close();

Java JSONArray from Javascript JSONArray

I am passing a json object from javascript to a java servlet using ajax.
var jsonObj = JSON.stringify(objArray); //Then I pass it to Java using ajax.
In my Java I am getting the json string from the request, then creating a jsonarray, then looping through that array and i'm getting errors when trying to pull one of the json objects from the array.
String dataObj = request.getParameter("obj");
String sql = request.getParameter("sql");
ArrayList<Object> returnArray = new ArrayList<Object>();
int key;
//Get type of object being passed.
JSONArray jsonArray = JSONArray.fromObject(dataObj);
for(int i=0; i<jsonArray.size(); i++) {
String obj = new Gson().toJson(jsonArray.getJSONObject(i)); //This is where i'm getting an error
String className = getClassName(jsonArray.getJSONObject(i));
Class targetClass = null;
try {
targetClass = Class.forName(className);
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
//Create Object
Object data = new Gson().fromJson(obj, targetClass);
I'm posting the relevant code, the for loop isn't closed because the rest of the code is quite long, and this is the part where i'm getting the error.
net.sf.json.JSONException: JSONArray[0] is not a JSONObject.
Here is what the json array looks like when its passed in from javascript. This is a println of the jsonArray object.
[{"number":"(123) 456-7050","type":"Home","contactId":1,"id":16662,"className":"beans.PhoneNumber","position":0}]
With one object in it, this code works. But as soon as I get 2 or more, my error comes up.
[[{"number":"(123) 456-7050","type":"Home","contactId":1,"id":16662,"className":"beans.PhoneNumber","position":1},{"number":"(555) 555-1233","type":"Mobile","contactId":1,"id":16656,"className":"beans.PhoneNumber","position":0},{"number":"(999) 999-9999","type":"Home","contactId":1,"id":16664,"className":"beans.PhoneNumber","position":3},{"number":"(222) 222-2222","type":"Home","contactId":1,"id":16666,"className":"beans.PhoneNumber","position":4}]]
It almost looks like when i'm passing more than one object, it create an array of an array, which could be why its not working. But how do I avoid doing that when i'm passing a jsonarray from javascript? Using just the dataObj I have no access to size or get to loop through it.

[
[
{
"number":"(123) 456-7050","type":"Home",
"contactId":1,
"id":16662,
"className":"beans.PhoneNumber",
"position":1
},
{
"number":"(555) 555-1233",
"type":"Mobile",
"contactId":1,
"id":16656,
"className":"beans.PhoneNumber",
"position":0
},
{
"number":"(999) 999-9999",
"type":"Home",
"contactId":1,
"id":16664,
"className":"beans.PhoneNumber",
"position":3
},
{
"number":"(222) 222-2222",
"type":"Home",
"contactId":1,
"id":16666,
"className":"beans.PhoneNumber",
"position":4
}
]
]
This is not an array of objects. This is an array of arrays of objects. According to your description, you are expecting something like the following to be fed to your Java:
[{"foo":"bar"}, {"bar":"baz"}]
But you are really trying to parse:
[[{"foo":"bar"}, {"bar":"baz"}]]

I am not completely sure, because you have not shared the json that you are trying to parse, but the most probable error you have is just what it says: the first element of the array is not JSONObject. Note that string values, lons and booleans are not JSONObjects. I would suggest you to use the more genereal JSONArray.get and check instance of what class it is. Maybe this can head you to the problem with the json you have. If I got it completely wrong - write back and I will try to help. In such a case it will be still useful to share the results of the proposed experiment.
EDIT:
This is double array -> maybe you using getJSONArray(int index) will help you. as the other answer mentioned - this is array of arrays. Also consider changing the javascript to reduce the level of arrays included.

GWT: Dealing with incoming JSON string

I am working on a GWT app that is receiving a JSON string, and I'm having a hard time getting down to the values of each object. I'm trying to transfer the incoming JSON string into an array of objects.
Here is the JSON (from Firebug response tab), The "d" is a .NET thing (Web Service Being Consumed is C#.
{
"d": [
{
"__type": "Event",
"ID": 30,
"Bin": 1,
"Date": "\/Date(1281544749000)\/",
"Desc": "Blue with white stripes.",
"Category": "1"
},
{
"__type": "Event",
"ID": 16,
"Bin": 3,
"Date": "\/Date(1281636239000)\/",
"Desc": "Yellow with pink stripes",
"Category": "1"
}
]
}
I'm trying to parse the JSON into objects, and then insert them into an array. I'm able to use Window.alert and get the entire "d" object to echo. However, when I try to access the elements of the array, GWT debugger just crashes.
//My GWT array to receive JSON Array
ArrayList<Item> itemInfo = new ArrayList<Item>();
//Getting response JSON into something I can work with.(THIS FAILS)
JSONArray jsonValue = JSONParser.parse(incomingJsonRespone);
//Just trying to verify I'm getting values
for (int i=0; i<jsonValue.size(); i++) {
JSONValue jsonItem = = JsonValue.get(i).getString();
Window.alert(jsonItem);
itemInfo.add(jsonItem);
}
I think I have narrowed down the problem to where the JSONArray instance is being created. Is there something blatantly wrong with how I'm trying to do this, because I'm not getting much help in the way of error messages?

In response to RMorrisey's comment:
Actually, it's more convoluted :/ It would look something like this (code untested, but you should get the general idea):
JSONValue jsonValue;
JSONArray jsonArray;
JSONObject jsonObject;
JSONString jsonString;
jsonValue = JSONParser.parseStrict(incomingJsonRespone);
// parseStrict is available in GWT >=2.1
// But without it, GWT is just internally calling eval()
// which is strongly discouraged for untrusted sources
if ((jsonObject = jsonValue.isObject()) == null) {
Window.alert("Error parsing the JSON");
// Possibilites: error during download,
// someone trying to break the application, etc.
}
jsonValue = jsonObject.get("d"); // Actually, this needs
// a null check too
if ((jsonArray = jsonValue.isArray()) == null) {
Window.alert("Error parsing the JSON");
}
jsonValue = jsonArray.get(0);
if ((jsonObject = jsonValue.isObject()) == null) {
Window.alert("Error parsing the JSON");
}
jsonValue = jsonObject.get("Desc");
if ((jsonString = jsonValue.isString()) == null) {
Window.alert("Error parsing the JSON");
}
Window.alert(jsonString.stringValue()); // Finally!
As you can see, when using JSONParser you have to/should be very cautious - that's the whole point, right? To parse an unsafe JSON (otherwise, like I suggested in the comments, you should go with JavaScript Overlay Types). You get a JSONValue, check if it's really what you think it should be, say, a JSONObject, you get that JSONObject, check if it has the "xyz" key, you get a JSONValue, rinse and repeat. Not the most interesting work, but at least its safer than just calling eval() on the whole JSON :)
Attention: as Jason pointed out, prior to GWT 2.1, JSONParser used eval() internally (it only had a parse() method - GWT 2.0 javadocs vs GWT 2.1). In GWT 2.1, parse() became deprecated and two more methods were introduced - parseLenient() (uses eval() internally) and parseStrict() (the safe approach). If you really have to use JSONParser, then I'd suggest upgrading to GWT 2.1 M2, because otherwise you might as well use JSOs. As an alternative to JSONParser for untrusted sources, you could try integrating json2.js as a JSON parser via JSNI.
PS: cinqoTimo, JSONArray jsonValue = JSONParser.parse(incomingJsonRespone); obviously doesn't work because JSONParser.parse has a return type of JSONValue, not JSONArray - didn't your IDE (Eclipse + Google Plugin?) warn you? Or at least the compiler.

It looks like you don't have an array, but a single root object, whose property called 'd' is an array. I'm not familiar with that specific API, but maybe you can try retrieving a JSONObject or similar instead of an array?