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Trouble extracting values from JSON object in Java

Okay, I'm struggling here. I am getting the following JSON formated string from my php server (called "result") (edited! I was missing a curly brace at the end):
{"L1":[{"UserName":"User1","Avatar":"1"},{"UserName":"User2","Avatar":"2"},{"UserName":"User3","Avatar":"3"}],"L2":[{"UserName":"User4","Avatar":"4"},{"UserName":"User5","Avatar":"5"}]}
I'm trying to extract an ArrayList with the Avatar numbers from the L1 object(?). But I get an error
org.json.JSONException: Value
[{"UserName":"User1","Avatar":"1"},{"UserName":"User2","Avatar":"2"},{"UserName":"User3","Avatar":"3"}]
at L1 of type org.json.JSONArray cannot be converted to JSONObject
Here's my code:
try {
JSONObject jsonObject = new JSONObject(result);
JSONArray jsonArray = new JSONArray(jsonObject.getJSONObject("L1"));
ArrayList<Integer> arrList = new ArrayList<>();
if (jsonArray != null) {
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject json = jsonArray.getJSONObject(i);
arrList.add(json.getInt("Avatar"));
AvatarList = arrList;
}
}
String query_result = "SUCCESS";
if (query_result.equals("FAILURE")) {
} else {
setAvatars(AvatarList);
}
} catch (JSONException e) {
Log.e("log_tag", "Error converting result "+e.toString());
}
If I use
jsonObject.getJSONArray("L1")
I get the same error.
Any suggestions?
Thanks in advance!
(edit: I made a mistake in the original post. There was a missing curly brace in the JSON string. Thanks to those who caught that)

Try the below one.Its working fine. I'm using json-simple-1.1.1 jar
String r="{\"L1\":[{\"UserName\":\"User1\",\"Avatar\":\"1\"},{\"UserName\":\"User2\",\"Avatar\":\"2\"},{\"UserName\":\"User3\",\"Avatar\":\"3\"}],\"L2\":[{\"UserName\":\"User4\",\"Avatar\":\"4\"},{\"UserName\":\"User5\",\"Avatar\":\"5\"}]}";
Object obj=JSONValue.parse(r);
JSONObject jsonObject = (JSONObject) obj;
JSONArray jsonArray = (JSONArray) jsonObject.get("L1");
ArrayList<Integer> arrList = new ArrayList<>();
if (jsonArray != null) {
for (int i = 0; i < jsonArray.size(); i++) {
JSONObject json = (JSONObject) jsonArray.get(i);
arrList.add((Integer.parseInt((String) json.get("Avatar"))));
AvatarList = arrList;
}
}
String query_result = "SUCCESS";
if (query_result.equals("FAILURE")) {
} else {
setAvatars(AvatarList);
}

This ended up working for me if anyone stumbles upon this. I don't really understand why this worked and my original method didn't... something to do with JSONObjects vs JSONArrays vs Strings and things like [, {, }, and ] probably.
try {
JSONObject jsonObject = new JSONObject(result);
JSONArray jsonArray = new JSONArray(jsonObject.getString("L1"));
ArrayList<Integer> arrList = new ArrayList<>();
if (jsonArray != null) {
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject json = jsonArray.getJSONObject(i);
arrList.add(json.getInt("Avatar"));
AvatarList = arrList;
}
}

Convert JSONObject to List<JSONObject> or a String to List<JSONObject>

I submit a query from my Java application, which upon running on Elasticsearch server returns the result in the form of a string. I want the result as a list of JSONObject objects. I can convert the string to a JSONObject using JSONObject jsonResponse = new JSONObject(responseString).
Is there any method by which I can get this in the form of a List<JSONObject>?

Instead of using JSONObject you may use JSONArray. If you really need to convert it to a List you may do something like:
List<JSONObject> list = new ArrayList<JSONObject>();
try {
int i;
JSONArray array = new JSONArray(string);
for (i = 0; i < array.length(); i++)
list.add(array.getJSONObject(i);
} catch (JSONException e) {
System.out.println(e.getMessage());
}

There is an answer of your question:
https://stackoverflow.com/a/17037364/1979882
ArrayList<String> listdata = new ArrayList<String>();
JSONArray jArray = (JSONArray)jsonObject;
if (jArray != null) {
for (int i=0;i<jArray.length();i++){
listdata.add(jArray.get(i).toString());
}
}

This method is really easy and works too
try {
JSONObject jsonObject = new JSONObject(THESTRINGHERE);
String[] names = JSONObject.getNames(jsonObject);
JSONArray jsonArray = jsonObject.toJSONArray(new JSONArray(names));
ArrayList<String> listdata = new ArrayList<String>();
JSONArray jArray = (JSONArray)jsonArray;
if (jArray != null) {
for (int i=0;i<jArray.length();i++){
listdata.add(jArray.get(i).toString());
}
}
// System.out.println(listdata);
} catch (Exception e) {
System.out.println(e.getMessage());
}

JSON Array to ArrayList<List<String>>

I have an JSON Array that looks like this
[["ONE","CAT",0],["TWO","DOG",0]]
And I want to make it into an ArrayList<List<String>>, I am trying to loop though it but can't get it to work.
I have tried
for (ArrayList arrayList: jsonArray) {
for (Object array : arrayList) {
}
}
But then I got a compilation error. I'm not able to loop through an Array of JSON Objects.

You can try this way -
try {
ArrayList<Object> _arrList = new ArrayList<Object>();
JSONArray _jArryMain = new JSONArray("YOUR_JSON_STRING");
if (_jArryMain.length()>0) {
for (int i = 0; i < _jArryMain.length(); i++) {
JSONArray _jArraySub = _jArryMain.getJSONArray(i);
_arrList.add(_jArraySub);
}
}
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

First, Java does not like mixed types. If you are sure you can use List<List<String>> then keep reading.
I recommend using the Jackson Library and ObjectMapper#readTree.
ObjectMapper mapper = new ObjectMapper();
JsonNode node = mapper.readTree("JSON CONTENT");
List<List<String>> convertedList = new ArrayList<List<String>>();
for (JsonNode arrNode : node) {
List<String> currList = new ArrayList<String>();
convertedList.add(currList);
for (JsonNode dataNode : arrNode) {
currList.add(dataNode.asText());
}
}
System.out.println(convertedList);

I guess this is what your looking for :
try {
ArrayList<ArrayList<Object>> mainarraylist = new ArrayList<ArrayList<Object>>();
JSONArray jsonarray = new JSONArray(yourstringjson);
if (jsonarray.length()>0) {
for (int i = 0; i < jsonarray.length(); i++) {
ArrayList<String> subarray;
JSONArray jsonsubarray = jsonarray.getJSONArray(i);
for (int i = 0; i < jsonsubarray.length(); i++) {
subarray = new ArrayList<String>;
jsonsubarray.add(jsonsubarray.get(i));
}
mainarraylist.add(jsonsubarray);
}
}
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
This will give you the result: mainarraylist.get(0).get(0) equals ONE
FYI: The code is not compiled, so there might some errors. This is an abstract for your solution.

you can use this code to solve your problems
String jsonValue = "[[\"ONE\",\"CAT\",0],[\"TWO\",\"DOG\",0]]";
try{
JSONArray array = (JSONArray) new JSONTokener(jsonValue).nextValue();
ArrayList<JSONArray> arrayList = new ArrayList<>();
arrayList.add(array);
for (int i=0;i<arrayList.get(arrayList.size()-1).length();i++) {
try {
JSONArray arr = arrayList.get(arrayList.size()-1).getJSONArray(i);
for (int j = 0; j < arr.length(); j++) {
System.out.println("Value = " + arr.get(j));
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}catch (JSONException e){
}

1. try {
String abc = "[[\"ONE\",\"CAT\",0],[\"TWO\",\"DOG\",0]]";
JSONArray jsonarray = new JSONArray(abc);
if (jsonarray.length()>0) {
for (int i = 0; i < jsonarray.length(); i++) {
JSONArray jsonsubarray = jsonarray.getJSONArray(i);
for (int j = 0; j < jsonsubarray.length(); j++) {
Log.d("Value---->",""+jsonsubarray.get(j));
}
}
}
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

To parse a json array to a list of list i have created the following method.
public static List<List<String>> convertJsonToListofList(String json) throws Exception{
JSONArray jArray=new JSONArray(json);
List<List<String>> list = new ArrayList<List<String>>();
int length = jArray.length();
for(int i=0; i<length;i++) {
JSONArray array;
List<String> innerlist = new ArrayList<String>();
String innerJsonArrayString = jArray.get(i).toString();
JSONArray innerJsonArray = new JSONArray(innerJsonArrayString);
int innerLength = innerJsonArray.length();
for(int j=0;j<innerLength;j++){
String str = innerJsonArray.getString(j);
innerlist.add(str);
}
list.add(innerlist);
}
return list;
}
You have to call this method in this way:
try {
List<List<String>> listoflist = convertJsonToListofList("[[\"ONE\",\"CAT\",0],[\"TWO\",\"DOG\",0]]");
System.out.println(listoflist);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
The output I have obtained is this one
07-09 13:00:42.268: I/System.out(19986): [[ONE, CAT, 0], [TWO, DOG, 0]]
I hope this is what you are looking for :)

Another Jackson approach.
ObjectMapper mapper = new ObjectMapper();
String json = "[[\"ONE\",\"CAT\",0],[\"TWO\",\"DOG\",0]]";
List<List<String>> output = new ArrayList<List<String>>();
JsonNode root = mapper.readTree(json);
for (JsonNode child : root) {
output.add(mapper.readValue(child.traverse(), new TypeReference<ArrayList<String>>(){}));
}

Get JSON Array into strings.

I have a webservice which returns a JSON array in this format:
[{"imageid":"3","userid":"1","imagepath":"SLDFJNDSKJFN","filterid":"1","dateadded":"2014-05-06 21:20:18.920257","public":"t"},
{"imageid":"4","userid":"1","imagepath":"dsfkjsdkfjnkjdfsn","filterid":"1","dateadded":"2014-05-06 21:43:37.642748","public":"t"}]
I need to get all the attributes seperately? How would I do this?
I know how to do it with JSONObject if there is just 1 thing being returned, but how does it work when multiple items are returned?
Thanks

try {
JSONArray jArray = new JSONArray(jsonString);
String s = new String();
for (int i = 0; i < jArray.length(); i++) {
s = jArray.getJSONObject(i).getString("imageid").toString();
s = jArray.getJSONObject(i).getString("userid").toString();
}
} catch (JSONException je) {
}

Create an Object class with all variables, create a List for this Object, add all objects in your JSONArray to the list, use the one you need.
List<YourObject> objList = new ArrayList<YourObject>();
JSONArray a = new JSONArray(response);
int size = a.length();
for (int i=0 ; i<size ; i++){
JSONObject aa = a.getJSONObject(i);
String id = aa.getString("imageid");
String userid = aa.getString("userid");
String imagepath = aa.getString("imagepath");
String filterid = aa.getString("filterid");
String dateadded = aa.getString("dateadded");
String publicText = aa.getString("public");
YourObject obj = new YourObject(id,userid,imagepath,filterid,dateadded,publicText);
objList.add(obj);
}

So what you are having here is some JSON objects inside a JSON array.
What you want to do is this:
JSONArray array = ...;
for (int i = 0; i < array.length(); i++) {
JSONObject o = array.getJSONObject(i);
// Extract whatever you want from the JSON object.
}
I hope it helped.

You can use JSONArray to parse array of JSON response.
private void parseJsonArray(String response) {
try {
JSONArray array = new JSONArray(response);
for(int i=0;i<array.length();i++){
JSONObject jsonObject = array.getJSONObject(i);
String ImageId = jsonObject.getString("imageid");
Log.v("JSON Parser", "ImageId: "+ImageId);
}
} catch (Exception e) {
e.printStackTrace();
}
}

Convert Json Array to normal Java list

Is there a way to convert JSON Array to normal Java Array for android ListView data binding?

ArrayList<String> list = new ArrayList<String>();
JSONArray jsonArray = (JSONArray)jsonObject;
if (jsonArray != null) {
int len = jsonArray.length();
for (int i=0;i<len;i++){
list.add(jsonArray.get(i).toString());
}
}

If you don't already have a JSONArray object, call
JSONArray jsonArray = new JSONArray(jsonArrayString);
Then simply loop through that, building your own array. This code assumes it's an array of strings, it shouldn't be hard to modify to suit your particular array structure.
List<String> list = new ArrayList<String>();
for (int i=0; i<jsonArray.length(); i++) {
list.add( jsonArray.getString(i) );
}

Instead of using bundled-in org.json library, try using Jackson or GSON, where this is a one-liner. With Jackson, f.ex:
List<String> list = new ObjectMapper().readValue(json, List.class);
// Or for array:
String[] array = mapper.readValue(json, String[].class);

Maybe it's only a workaround (not very efficient) but you could do something like this:
String[] resultingArray = yourJSONarray.join(",").split(",");
Obviously you can change the ',' separator with anything you like (I had a JSONArray of email addresses)

Using Java Streams you can just use an IntStream mapping the objects:
JSONArray array = new JSONArray(jsonString);
List<String> result = IntStream.range(0, array.length())
.mapToObj(array::get)
.map(Object::toString)
.collect(Collectors.toList());

Use can use a String[] instead of an ArrayList<String>:
It will reduce the memory overhead that an ArrayList has
Hope it helps!
String[] stringsArray = new String[jsonArray.length()];
for (int i = 0; i < jsonArray.length; i++) {
parametersArray[i] = parametersJSONArray.getString(i);
}

I know that question is about JSONArray but here's example I've found useful where you don't need to use JSONArray to extract objects from JSONObject.
import org.json.simple.JSONObject;
import org.json.simple.JSONValue;
String jsonStr = "{\"types\":[1, 2]}";
JSONObject json = (JSONObject) JSONValue.parse(jsonStr);
List<Long> list = (List<Long>) json.get("types");
if (list != null) {
for (Long s : list) {
System.out.println(s);
}
}
Works also with array of strings

Here is a better way of doing it: if you are getting the data from API. Then PARSE the JSON and loading it onto your listview:
protected void onPostExecute(String result) {
Log.v(TAG + " result);
if (!result.equals("")) {
// Set up variables for API Call
ArrayList<String> list = new ArrayList<String>();
try {
JSONArray jsonArray = new JSONArray(result);
for (int i = 0; i < jsonArray.length(); i++) {
list.add(jsonArray.get(i).toString());
}//end for
} catch (JSONException e) {
Log.e(TAG, "onPostExecute > Try > JSONException => " + e);
e.printStackTrace();
}
adapter = new ArrayAdapter<String>(ListViewData.this, android.R.layout.simple_list_item_1, android.R.id.text1, list);
listView.setAdapter(adapter);
listView.setOnItemClickListener(new OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
// ListView Clicked item index
int itemPosition = position;
// ListView Clicked item value
String itemValue = (String) listView.getItemAtPosition(position);
// Show Alert
Toast.makeText( ListViewData.this, "Position :" + itemPosition + " ListItem : " + itemValue, Toast.LENGTH_LONG).show();
}
});
adapter.notifyDataSetChanged();
adapter.notifyDataSetChanged();
...

we starting from conversion [ JSONArray -> List < JSONObject > ]
public static List<JSONObject> getJSONObjectListFromJSONArray(JSONArray array)
throws JSONException {
ArrayList<JSONObject> jsonObjects = new ArrayList<>();
for (int i = 0;
i < (array != null ? array.length() : 0);
jsonObjects.add(array.getJSONObject(i++))
);
return jsonObjects;
}
next create generic version replacing array.getJSONObject(i++) with POJO
example :
public <T> static List<T> getJSONObjectListFromJSONArray(Class<T> forClass, JSONArray array)
throws JSONException {
ArrayList<Tt> tObjects = new ArrayList<>();
for (int i = 0;
i < (array != null ? array.length() : 0);
tObjects.add( (T) createT(forClass, array.getJSONObject(i++)))
);
return tObjects;
}
private static T createT(Class<T> forCLass, JSONObject jObject) {
// instantiate via reflection / use constructor or whatsoever
T tObject = forClass.newInstance();
// if not using constuctor args fill up
//
// return new pojo filled object
return tObject;
}

You can use a String[] instead of an ArrayList<String>:
Hope it helps!
private String[] getStringArray(JSONArray jsonArray) throws JSONException {
if (jsonArray != null) {
String[] stringsArray = new String[jsonArray.length()];
for (int i = 0; i < jsonArray.length(); i++) {
stringsArray[i] = jsonArray.getString(i);
}
return stringsArray;
} else
return null;
}

We can simply convert the JSON into readable string, and split it using "split" method of String class.
String jsonAsString = yourJsonArray.toString();
//we need to remove the leading and the ending quotes and square brackets
jsonAsString = jsonAsString.substring(2, jsonAsString.length() -2);
//split wherever the String contains ","
String[] jsonAsStringArray = jsonAsString.split("\",\"");

To improve Pentium10s Post:
I just put the elements of the JSON array into the list with a foreach loop. This way the code is more clear.
ArrayList<String> list = new ArrayList<String>();
JSONArray jsonArray = (JSONArray)jsonObject;
jsonArray.forEach(element -> list.add(element.toString());

private String[] getStringArray(JSONArray jsonArray) throws JSONException {
if (jsonArray != null) {
String[] stringsArray = new String[jsonArray.length()];
for (int i = 0; i < jsonArray.length(); i++) {
stringsArray[i] = jsonArray.getString(i);
}
return stringsArray;
} else
return null;
}

You can use iterator:
JSONArray exportList = (JSONArray)response.get("exports");
Iterator i = exportList.iterator();
while (i.hasNext()) {
JSONObject export = (JSONObject) i.next();
String name = (String)export.get("name");
}

I know that the question was for Java. But I want to share a possible solution for Kotlin because I think it is useful.
With Kotlin you can write an extension function which converts a JSONArray into an native (Kotlin) array:
fun JSONArray.asArray(): Array<Any> {
return Array(this.length()) { this[it] }
}
Now you can call asArray() directly on a JSONArray instance.

How about using java.util.Arrays?
List<String> list = Arrays.asList((String[])jsonArray.toArray())