Develop Reference

JSON: Treat many objects as array of object

I have a JSON Like this
{ "video":{
"video_3745":{ },
"video_3437":{ },
"video_3471":{ },
"video_4114":{ }
}
}
In which every "video_xxxx" is of the SAME type. Is there a way to treat the "video" field as an array of that type? I need to iterate over all the videos, but the API is not sending them in an array, and I don't know how to model a class to receive this JSON without having to manually specify all the field names...
does GSON or LoganSquare have anything to help me out with this?

Try something like this
JSONObject video= json.getJSONObject("video"); // json is the whole response
Iterator x = video.keys();
JSONArray jsonArray = new JSONArray();
while (x.hasNext()){
String key = (String) x.next();
jsonArray.put(video.get(key));
}

You can't treat them as an array, but with the org.json.JSONObject class you can get the list of keys and iterate over them. I believe in GSON the JsonObject.entrySet method will allow something similar.
https://developer.android.com/reference/org/json/JSONObject.html
https://google.github.io/gson/apidocs/com/google/gson/JsonObject.html

Convert from JSONArray to ArrayList<CustomObject> - Android

I converted an ArrayList to an JSONArray. How can I convert it back?
The final result must be an ArrayList. Thank you in advance.
EDIT:
This is how I convert the ArrayList to JSONArray:
String string_object= new Gson().toJson(MyArrayList<OBJECT>);
JSONArray myjsonarray = new JSONArray(string_object);

You can convert your JsonArray or json string to ArrayList<OBJECT> using Gson library as below
ArrayList<OBJECT> yourArray = new Gson().fromJson(jsonString, new TypeToken<List<OBJECT>>(){}.getType());
//or
ArrayList<OBJECT> yourArray = new Gson().fromJson(myjsonarray.toString(), new TypeToken<List<OBJECT>>(){}.getType());
Also while converting your ArrayList<OBJECT> to JsonArray, no need to convert it to string and back to JsonArray
JsonArray myjsonarray = new Gson().toJsonTree(MyArrayList<OBJECT>).getAsJsonArray();
Refer Gson API documentation for more details. Hope this will be helpful.

JSONArray is just a subclass of object, so if you want to get the JSONObjects out of a JSONArray into some other form, JSONArray doesn't have any convenient way to do it, so you have to get each JSONObject and populate your ArrayList yourself.
Here is a simple way to do it:
ArrayList<JSONObject> arrayList = new ArrayList(myJSONArray.length());
for(int i=0;i < myJSONArray.length();i++){
arrayList.add(myJSONArray.getJSONObject(i));
}
EDIT:
OK, you edited your code to show that you are using GSON. That is a horse of a different color. If you use com.google.gson.JsonArray instead of JSONArray, you can use the Gson.fromJson() method to get an ArrayList.
Here is a link: Gson - convert from Json to a typed ArrayList

Unfortunately, this will require a little work on your part. Gson does not support deserializing generic collections of arbitrary objects. The Gson User Guide topic Serializing and Deserializing Collection with Objects of Arbitrary Types list three options for doing what you want. To quote the relevant parts of the guide:
You can serialize the collection with Gson without doing anything specific: toJson(collection) would write out the desired output.
However, deserialization with fromJson(json, Collection.class) will not work since Gson has no way of knowing how to map the input to the types. Gson requires that you provide a genericised version of collection type in fromJson. So, you have three options:
Option 1: Use Gson's parser API (low-level streaming parser or the DOM parser JsonParser) to parse the array elements and then use Gson.fromJson() on each of the array elements. This is the preferred approach. Here is an example that demonstrates how to do this.
Option 2: Register a type adapter for Collection.class that looks at each of the array members and maps them to appropriate objects. The disadvantage of this approach is that it will screw up deserialization of other collection types in Gson.
Option 3: Register a type adapter for MyCollectionMemberType and use fromJson with Collection<MyCollectionMemberType>
This approach is practical only if the array appears as a top-level element or if you can change the field type holding the collection to be of type Collection<MyCollectionMemberType>.
See the docs for details on each of the three options.

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;
}

Try this,
ArrayList<**YOUCLASS**> **YOURARRAY** =
new Gson().fromJson(oldJSONArray.toString(),
new TypeToken<List<**yourClass**>>(){}.getType());

Android - how to format objects in JSON

I have this class:
class Type{
public int id;
public String name;
}
and I want to format object in JSON this way
{[1,"superMarket"],[2,"restaurant "]}
and also put data from JSON to "Type" object
can some one help me please......

You can get an easy to understand example for encoding and parsing json:
Android JSON Tutorial: Create and Parse JSON data
and
JSON in Android - Tutorial

you nee to use a jasonArray and thee jsonObject ro do this..
you can viw this answer
Android create a JSON array of JSON Objects

Type to JSON
JSONObject jsonObj = new JSONObject();
jsonObj.putString("id", id);
jsonObj.putString("name", name);
You can add as many jsonObjs to JSONArray.
JSON to Type
Type type = new Type();
type.setId(jsonObj.optString("id"));
type.setName(jsonObj.optString("name"));

android how to parse json

public void HelloWord {
for (int i = 0; i < 20; i++) {
Log.d("Great");
}
}
The code above doesn't work why?
I try to get value name
Does anybody know where is the problem?
org.json.JSONException: Value ...Content of link... at
org.json.JSON.typeMismatch at org.json.JSONArray.

I prefer to use the GSON library, as it is a fast and effective JSON parser. Once added to the project you will need to create classes to represent the data returned. You then can call a single function to create your objects for you:
gson.fromJson();
An exceptionally good article on the use of GSON can be found at http://www.javacodegeeks.com/2011/01/android-json-parsing-gson-tutorial.html - it even uses Twitter for the example.

I think that you are missing the way that JSON works. Anything in {} is an Object, while [] designates an array. So the root of the twitter feed is a JSONObject, NOT a JSONArray:
Try something more like this:
JSONObject obj = new JSONObject(mStringBuilder.toString());
JSONObject trends = obj.getJSONObject("trends");
JSONArray today = trends.getJSONArray("2012-04-10");
for (int i = 0; i < today.length(); i++) {
JSONObject tag = today.getJSONObject(i);
String name = tag.getString("name");
// do whatever with name
}
Much easier, and its clearer how it works. JSONObjects are dictionaries, with a simple mapping between keys and values - each Object ({}) can contain either more objects, or arrays ([]) which can contain either simple integers or more objects

Trouble with Android JSONObject from Grails webservice

Okay I am quering data from a Grails webservice that returns JSON. The JSON when viewed with the JSONViewer app parses fine. When I take that same string and use JSONObject(string) in my Android app I get "value of String cannot be converted to JSONObject."
Here's my JSON string
[[{"class":"mygrails.TopTen","id":491,"ttAmount":14200000,"ttMlId":402,"ttRank":1,"ttWeekId":1108},{"class":"mygrails.MovieList","id":402,"mlApproved":1,"mlApprovedId":5,"mlMovieId":"GNOMEOAN","mlReleaseDate":"2011-03-08T07:41:45Z","mlTitle":"Gnomeo and Juliet","mlWeekId":1106}]]
Now the JSON is comes from the standard JSON conversion of a SQL data using render from the groovy file through the import grails.converters.JSON.
... //(call to render JSON in the groovy file)
def a
a = Table.findAll("from someTable as st where st.id=" params.id)
render a as JSON
...
So I am not sure what I doing wrong and why the JSON looks a little off to me. (still new to JSON)

In json if you see "[]" means its a json array and if you see "{}" it is an json object. Both of then can have the other nested inside then.
In your case the string the starts with json array.
So try something like the following
String str = "[[{"class":"mygrails.TopTen","id":491,"ttAmount":14200000,"ttMlId":402,"ttRank":1,"ttWeekId":1108},{"class":"mygrails.MovieList","id":402,"mlApproved":1,"mlApprovedId":5,"mlMovieId":"GNOMEOAN","mlReleaseDate":"2011-03-08T07:41:45Z","mlTitle":"Gnomeo and Juliet","mlWeekId":1106}]]";
JSONArray jsonArray = new JSONArray(str);
jsonArray = jsonArray.getJSONArray(0);
JSONObject jsonObject = jsonArray.getJSONObject(0);
String class = jsonObject.getString("class"); // class will value "mygrails.TopTen"

Try to create an JSONArray from the String instead of JSONObject. I didn't test this but that should do the trick: you have two nested arrays that contain then actual data.

Check out your JSON online with http://jsonformat.com/
http://www.freeformatter.com/json-formatter.html
JSON Viewer
http://jsonviewer.stack.hu/
Paste your text in there and you can see what you should parse: