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Getting element of JSON object when key isn't the same [Android]

I want to learn a bit more about android and wanted to create an app that will track the price of cryptocurrencies. I choosed this API: https://www.cryptocompare.com/api/#introduction
My problem is the following: When I want to get the list of all the coin the JSON response looks like this:
{
"Response": "Success",
"Message": "Coin list succesfully returned!",
"BaseImageUrl": "https://www.cryptocompare.com",
"BaseLinkUrl": "https://www.cryptocompare.com",
"Data": {
"42": {
"Id": "4321",
"Url": "/coins/42/overview",
"ImageUrl": "/media/19984/42.png",
"Name": "42",
"CoinName": "42 Coin",
"FullName": "42 Coin (42)",
"Algorithm": "Scrypt",
"ProofType": "PoW",
"FullyPremined": "0",
"TotalCoinSupply": "42",
"PreMinedValue": "N/A",
"TotalCoinsFreeFloat": "N/A",
"SortOrder": "34"
},
"365": {
"Id": "33639",
"Url": "/coins/365/overview",
"ImageUrl": "/media/352070/365.png",
"Name": "365",
"CoinName": "365Coin",
"FullName": "365Coin (365)",
"Algorithm": "X11",
"ProofType": "PoW/PoS",
"FullyPremined": "0",
"TotalCoinSupply": "2300000000",
"PreMinedValue": "299000000",
"TotalCoinsFreeFloat": "N/A",
"SortOrder": "916"
},
(here is the URL I use (https://www.cryptocompare.com/api/data/coinlist/)
I want to keep all the informations about the coin (everything from "Data") but the key isn't the same.
How can I get those informations to create my differents coins?
Thank's in advance

You can use JSONObject#names() to get all the keys as JSONArray and loop the JSONArray.
JSONObject data = response.getJSONObject("Data");
JSONArray array = data.names(); // contains all the keys inside Data
// now loop the array
for (int i = 0; i < array.length(); i++ ) {
String key = array.getString(i); // 42 or 365 for your example code
JSONObject obj = data.getJSONObject(key); // contains the JSONObject of the key 42 or 365
}
Another way is to use JSONObject#keys() but that uses Iterator and hasNext() for iteration which is less performance efficient than the above normal for loop approach in Android.

The accepted answer is fine. I would like to show the way of parsing using Gson from your JSON. Here's how it can be parsed using Gson.
You need to have two classes.
Here's your APIResponse.java
public class APIResponse {
public String Response;
public String Message;
public String BaseImageUrl;
public String BaseLinkUrl;
public HashMap<String, DataObject> Data;
}
And the DataResponse class should look like
public class DataObject {
public String Id;
public String Url;
public String ImageUrl;
public String Name;
public String CoinName;
public String FullName;
public String Algorithm;
public String ProofType;
public String FullyPremined;
public String TotalCoinSupply;
public String PreMinedValue;
public String TotalCoinsFreeFloat;
public String SortOrder;
}
Now its pretty easy.
Type type = new TypeToken<APIResponse>(){}.getType();
APIResponse response = new Gson().fromJson(yourJsonString, type);
Now iterate the HashMap for getting the keys and corresponding values.

You can fetch all the keys and iterate as below
try {
JSONObject dataObj = obj.getJSONObject("Data"); //obj is the parent json object.
Iterator<?> keys = dataObj.keys();
while(keys.hasNext()) {
JSONObject coinObj = dataObj.getJSONObject(keys.next().toString());
}
} catch (JSONException e) {
e.printStackTrace();
}

Android Json parsing with sqlite

I am new in android JSON parsing android.
Below I mentioned my JSON value, please give the solution to how to parse the JSON value, thanks in advance my JSON Data:
Here I have category, categorybook, subcategory inside have subbook. I want to parse all the value and store it into sqlite with separate.
Like category book and sucategory book are stored seperate column in android sqlite table:
[
"category": {
"id": "1",
"name": "Education",
"categorybooks": [],
"subcategory": [
{
"id": "1",
"name": "tamil",
"subcategorybooks": []
},
{
"id": "2",
"name": "english",
"subcategorybooks": []
},
{
"id": "5",
"name": "maths",
"subcategorybooks": []
},
{
"id": "6",
"name": "science,
"subcategorybooks": []
},
{
"id": "7",
"name": "social",
"subcategorybooks": []
}
}
]
Here i have category 2 and its sub category books:
[
"category": {
"id": "2",
"name": "sports",
"categorybooks": [
{
"id": "4",
"name": "football",
},
{
"id": "5",
"name": "cricket",
}
],
"subcategory": []
}
]

First of all, you will need the VolleyLibrary. Then, you will need the GSON library. When creating GSON Request, you put the Object you want to get deserialized automatically from JSON, so you wont have to parse it manualy.
Second thing, you would want to create a db class that extends SQLiteHelper. When you create database, add the methods for adding, update and removing a row for every table that you create.
Below are the links that you need.
http://www.androidhive.info/2014/05/android-working-with-volley-library-1/
https://medium.com/android-news/android-networking-i-okhttp-volley-and-gson-72004efff196#.wp5lstsfv
http://www.androidhive.info/2011/11/android-sqlite-database-tutorial/

I will assume you already have the content of your json, if not you can use any Http Connection to get the content.
You can use Gson to parse your json content, first of all, you need to create your models based on your Json:
//note: Gson identify the attributes name as the same of from your
//json, if not you have to put an annotation above each attribute of
//your class:
public class Category(){
int id;
String name;
List<CategoryBook> categoryBooks;
}
public class CategoryBook(){
int id;
String name;
}
public class SubCategory(){
//Based on your json I will assume the attribute of this class
// is a model that have a list of an object that have an id and a name
//and a list of subcategorybooks
}
public class SubCategoryBooks(){
//class attributes that you not mentioned in your json
}
Then you just need to parse your object from content using gson,
if you have some doubts about how to parse using Gson follow this tutorial
For insert into database separate, you already have your objects with getters and setters, for example
you can get the List<CategoryBook> from your CategoryModel, then your can insert this list
inside a separate table of your database.

Hope It's Help you
JSONObject jsonObject = new JSONObject();
jsonObject.put("category",loaddata());
public JSONObject loaddata(){
JSONObject jsonObject = new JSONObject();
jsonObject.put("id","1");
jsonObject.put("name","Education");
jsonObject.put("categorybooks",addcategorybooks());
jsonObject.put("subcategory","addsubcategory()");
return jsonObject;
}
public JSONArray addcategorybooks(){
JSONArray JsonArray = new JSONArray();
JSONObject jObj = new JSONObject();
jObj.put("id", "1");
jObj.put("name", "Foot Ball");
JsonArray.put(jObj);
return JsonArray;
}
public JSONArray addsubcategory(){
JSONArray JsonArray = new JSONArray();
JSONObject jObj = new JSONObject();
jObj.put("id", "1");
jObj.put("name", "Foot Ball");
jObj.put("subcategorybooks", addsubcategorybooks());
JsonArray.put(jObj);
return JsonArray;
}
public JSONArray addsubcategorybooks(){
JSONArray JsonArray = new JSONArray();
JSONObject jObj = new JSONObject();
jObj.put("id", "1");
jObj.put("name", "Foot Ball");
JsonArray.put(jObj);
return JsonArray;
}

If i understood you correctly, the main problem is to get java model object from json.
There are several ways to do it. The most common are:
Using built-in tools to operate with Json. In this case you get org.json.JSONObject and get values using it's methods. See details f.e. here
Using gson library. In this case you create model class and you can fill the object with one code line. smth like Category category = gson.fromJson(yourJsonString, Category.class); See details in official tutorial

Parsing JSON file with different number of keys

My JSON file contains strings with the same keys but some of them doens't appear for some strings. For example:
{
"city": "CB1 2BH Cambridge",
"addr": "Devonshire Road 1",
"title": "Devonshire Arms",
"phone": "+44 1223 6610"
},
{
"city": "E8 1JH London",
"addr": "Amhurst Road 90",
"title": "Pembury Tavern",
"web": "http://www.individualpubs.co.uk/pembury/"
},
{
"web": "http://bandholmhotel.dk/",
"title": "Bandholm Hotel",
},
{
"city": "00100 Helsinki",
"addr": "Pohjoinen Rautatiekatu 23",
"title": "Helkan Baari",
"country": "FI"
},
How to correctly parse it in android?

Considering this is your JSONArray,
Try to do as following,
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject jObj = (JSONObject) jsonProductArray.getJSONObject(i);
String city = jObj.optString("city", "cityDefaultValue");
String addr = jObj.optString("addr", "addDefaultValue");
String title = jObj.optString("title", "titleDefaultValue");
String phone = jObj.optString("phone", "phoneDefaultValue");
}

One possible solution can be to have a modal class and use Gson library to parse the Json.
You can set some default values in your modal class, for keys whose value is not found in Json

Create an model class with the key of the json and parse it to the model class using gson.
A a = gson.fromJson(jsonRes.toString(),A.class);
here A is your model class and a is the instance of A

You can use Gson library.
Create something like that
class SomeObjects {
#SerializedName("city")
private String mCity;
#SerializedName("addr")
private String mAddres;
...
}
and in then
SomeObject obj = new Gson.fromJson(jsonString, SomeObject.class);
You also can sirialize right into array

Parsing JSON file in Android Application

How would I parse the following string in Android?
{
"C1": {
"name": "first name",
"address": "first address",
"lat": 36.072111,
"lng": 34.732112
},
"C2": {
"name": "second name",
"address": "second address",
"lat": 32.02132,
"lng": 34.000002
},
"C3": {
"name": "third name",
"address": "third address",
"lat": 37.05435,
"lng": 34.75703
}
}
I can't understand. Is it an objects inside of an object structure? How would this be parsed? How do I find how many objects I have?

Well, got it. the solution is to first get the names of the inner-objects:
JONObject json = new JSONObject(jsonString);
JSONArray namesArray = json.names();
which will give you an JSONArray of the existing objects inside.
Then run on it's objects to get each one of them:
for (int i = 0 ; i < namesArray.length() ; i ++)
{
currentObject = json.getJSONObject(namesArray.get(i).toString());
Log.d("TAG", "currentObject : "+currentObject.toString());
addCurrentObjectShopToObjectsListUsingGson(currentObject,objectsList);
}

You can use JSONObject to extract the contents of the structure.
An example can be shown below:
You can retrieve a JSONArray from your string with
JSONObject json = new JSONObject(jsonString);
JSONArray myArray = json.getJSONArray(ARRAY_NAME_HERE);
After doing so, you can extract the name of a person with
JSONObject person = myArray.getJSONObject(0); // retrieve the first person
String name = person.getString("name"); // get the person's name
Reference:
http://developer.android.com/reference/org/json/JSONObject.html

The string you've shown contains an outer object with 3 inner objects. Suppose you want to get C1.name. You would do this:
JSONObject root = new JSONObject(yourString);
JSONObject c1 = root.getJSONObject("C1");
String name = c1.getString("name");
However, I should point out one other thing, which is that the original string you are using is odd because it suggests that what you really want is an array. The code to parse would be different, of course, and involve JSONArray, but I think a better representation would look like this:
[
{"name":"first name","address":"...","lat":"...","lng":"..."},
{"name":"second name"...},
{"name":"third name"...}
]
So in this case, the outermost container is a JSONArray, not an object.

You need a "model" object that looks like this: (provided the hash is static).
public class TheCs extends BaseModel {
public OneC c1;
public OneC c2;
public OneC c3;
}
public class OneC extends BaseModel {
public String name;
public String address;
public float lat, lng;
}
public class BaseModel implements Serializable {
private static final long serialVersionUID = 1L;//use a random number here
}
Now when parsing with Gson, pass TheCs.class as the type.
If the Hash is not static you could (and Gson will do the right thing as far as I can remember), do something like:
public class TheCs extends BaseModel {
public List<OneC> someHash;
}

Phrasing Json Array using Gson for google search api

First of all Sorry for the really long post, now
And this is my class structure, no idea if it's right or wrong
public class GoogleResponse {
public ResponseDate responseData;
public String responseDetails;
public String responseStatus;
}
public class ResponseData {
public List<Result> results;
//public Cursor cursor;
}
public class Result {
public String titleNoFormatting;
public String unescapedUrl;
}
And this is the code for deserialization
Gson gson = new Gson();
GoogleResponse data[] = gson.fromJson(s, GoogleResponse[].class);\\s is the JSON string
In this program i just want to extract titlenoformating and unescapedurl, that's why i left out rest of the content from the class's.
I don't know if this is right or wrong, but when i do System.out.print(data);
I get nothing in logcat, i don't know how to access the data that is stored in data[].
What i want is to populate a listview using the titleNoFormating and open the corresponding unescapedurl on clicking any results via intent.
EDIT:
{
"results": [
{
"GsearchResultClass": "GwebSearch",
"unescapedUrl": "http://www.mediafire.com/?zcnqy5mmwmj",
"url": "http://www.mediafire.com/%3Fzcnqy5mmwmj",
"visibleUrl": "www.mediafire.com",
"cacheUrl": "http://www.google.com/search?q=cache:f6cE2lmmCioJ:www.mediafire.com",
"title": "Redman Funk From <b>Hell</b> 2010.zip",
"titleNoFormatting": "Redman Funk From Hell 2010.zip",
"content": "Redman Funk From <b>Hell</b> 2010.zip. <b>...</b> Share “Redman Funk From <b>Hell</b> 2010.zip”. Info . Facebook/Twitter. Email. Share by IM. Embed. HTML Embed Code. Sharing URL <b>...</b>",
"clicktrackUrl": "//www.google.com/url?q=http://www.mediafire.com/?zcnqy5mmwmj&sa=T&usg=AFQjCNGhKqruZDyj614zfvjuitABOJFrNQ&ei=BUQdTtbGLeWTmQWElOHzBw&ved=0CAQQFjAA"
},
{
"GsearchResultClass": "GwebSearch",
"unescapedUrl": "http://www.mediafire.com/?ymto5mjznwz",
"url": "http://www.mediafire.com/%3Fymto5mjznwz",
"visibleUrl": "www.mediafire.com",
"cacheUrl": "http://www.google.com/search?q=cache:aXARYHERXiQJ:www.mediafire.com",
"title": "This Routine is <b>Hell</b> - The Verve Crusade.zip - This, Routine, is <b>...</b>",
"titleNoFormatting": "This Routine is Hell - The Verve Crusade.zip - This, Routine, is ...",
"content": "Debut full-length The Verve Crusade by hardcore punk band This Routine is <b>Hell</b> from the Netherlands. Released by Shield Recordings in 2010.",
"clicktrackUrl": "//www.google.com/url?q=http://www.mediafire.com/?ymto5mjznwz&sa=T&usg=AFQjCNGd4xVGQkOlb8TMCdpH5tEIn2Ln5A&ei=BUQdTtbGLeWTmQWElOHzBw&ved=0CAYQFjAB"
}
]
}
This becomes valid so i guess i'll have to make up mu own method to get out this content

when i do System.out.print(data); I get nothing in logcat
Use android.util.Log.(), not System.out.println();
Concerning parsing the JSON, unfortunately the JSON listed in the original question is invalid, which leaves folks that might help guessing a bit. And the example JSON on Google's own search API documentation page is also invalid (though in a different way) -- it escapes the '[' and ']' characters, but the JSON spec does not allow those characters to be escaped.
Following is a corrected version of the example JSON from the Google search API documentation.
{
"responseData": {
"results": [
{
"GsearchResultClass": "GwebSearch",
"unescapedUrl": "http://en.wikipedia.org/wiki/Paris_Hilton",
"url": "http://en.wikipedia.org/wiki/Paris_Hilton",
"visibleUrl": "en.wikipedia.org",
"cacheUrl": "http://www.google.com/search?q=cache:TwrPfhd22hYJ:en.wikipedia.org",
"title": "<b>Paris Hilton</b> - Wikipedia, the free encyclopedia",
"titleNoFormatting": "Paris Hilton - Wikipedia, the free encyclopedia",
"content": "[1] In 2006, she released her debut album..."
},
{
"GsearchResultClass": "GwebSearch",
"unescapedUrl": "http://www.imdb.com/name/nm0385296/",
"url": "http://www.imdb.com/name/nm0385296/",
"visibleUrl": "www.imdb.com",
"cacheUrl": "http://www.google.com/search?q=cache:1i34KkqnsooJ:www.imdb.com",
"title": "<b>Paris Hilton</b>",
"titleNoFormatting": "Paris Hilton",
"content": "Self: Zoolander. Socialite <b>Paris Hilton</b>..."
}
],
"cursor": {
"pages": [
{
"start": "0",
"label": 1
},
{
"start": "4",
"label": 2
},
{
"start": "8",
"label": 3
},
{
"start": "12",
"label": 4
}
],
"estimatedResultCount": "59600000",
"currentPageIndex": 0,
"moreResultsUrl": "http://www.google.com/search?oe=utf8&ie=utf8..."
}
},
"responseDetails": null,
"responseStatus": 200
}
And here is an example program using Gson to deserialize this JSON to a Java data structure, and then retrieving the two target data elements.
import java.io.FileReader;
import java.math.BigInteger;
import java.util.List;
import com.google.gson.Gson;
public class Foo
{
public static void main(String[] args) throws Exception
{
Gson gson = new Gson();
Response response = gson.fromJson(new FileReader("input.json"), Response.class);
for (Result result : response.responseData.results)
{
System.out.println("titleNoFormatting: " + result.titleNoFormatting);
System.out.println("unescapedUrl: " + result.unescapedUrl);
}
// output:
// titleNoFormatting: Paris Hilton - Wikipedia, the free encyclopedia
// unescapedUrl: http://en.wikipedia.org/wiki/Paris_Hilton
// titleNoFormatting: Paris Hilton
// unescapedUrl: http://www.imdb.com/name/nm0385296/
}
}
class Response
{
ResponseData responseData;
String responseDetails;
int responseStatus;
}
class ResponseData
{
List<Result> results;
Cursor cursor;
}
class Result
{
String GsearchResultClass;
String unescapedUrl;
String url;
String visibleUrl;
String cacheUrl;
String title;
String titleNoFormatting;
String content;
}
class Cursor
{
List<Page> pages;
BigInteger estimatedResultCount;
int currentPageIndex;
String moreResultsUrl;
}
class Page
{
int start;
int label;
}