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Reading json file with multiple objects in java

I have written a program that reads a simple json file:
public static void main(String[] args) {
JSONParser parser = new JSONParser();
try {
JSONArray a = (JSONArray) parser.parse(new FileReader("C:/Users/Zonoid/Desktop/EQ.json"));
for (Object o : a)
{
JSONObject obj = (JSONObject) o;
String city = (String) obj.get("CITY");
System.out.println("City : " + city);
String loc = (String) obj.get("LOCATION");
System.out.println("Location : " + loc);
long el = (Long) obj.get("E_LEVEL");
System.out.println("Emergency Level : " + el);
long depth = (Long) obj.get("DEPTH");
System.out.println("Depth : " + depth);
long i = (Long) obj.get("INTENSITY");
System.out.println("Intensity :"+i);
System.out.println("\n");
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (ParseException e) {
e.printStackTrace();
}
}
with my json file being:
[{"CITY":"MUMBAI","LOCATION":"a" ,"E_LEVEL": 6,"DEPTH":10,"INTENSITY":5},
{"CITY":"MUMBAI","LOCATION":"b" ,"E_LEVEL": 8,"DEPTH":20,"INTENSITY":4},
{"CITY":"MUMBAI","LOCATION":"c" ,"E_LEVEL": 3,"DEPTH":13,"INTENSITY":5},
{"CITY":"MUMBAI","LOCATION":"d" ,"E_LEVEL": 6,"DEPTH":12,"INTENSITY":4},]
I am working on a project that deals with earthquake alerts and want to read their JSON files however I cannot import them in JSON Array. The file I want to import looks like this:
{
"type": "FeatureCollection",
"metadata": {
"generated": 1488472809000,
"url": "https:\/\/earthquake.usgs.gov\/earthquakes\/feed\/v1.0\/summary\/significant_week.geojson",
"title": "USGS Significant Earthquakes, Past Week",
"status": 200,
"api": "1.5.4",
"count": 2
},
"features": [
{
"type": "Feature",
"properties": {
"mag": 5.5,
"place": "42km WSW of Anchor Point, Alaska",
"time": 1488420690658,....
Please tell what changes should be made.

If you are trying to read from features only, first you need to read the whole file as an object. Then you can, read the array part in the following way:
Object object = parser.parse(new FileReader("C:/Users/Zonoid/Desktop/EQ.json"));
JSONObject jasonObject = (JSONObject) object;
JSONArray features = (JSONArray) jasonObject.get("features");

org.json.JSONException: No value for Name JSON extraction error

I am getting this error when I try to get the value for "Name" out of the following JSON:
{
"edges": [
{
"node": {
"Name": "Sunday River",
"Latitude": 44.4672,
"Longitude": 70.8472
}
},
{
"node": {
"Name": "Sugarloaf Mountain",
"Latitude": 45.0314,
"Longitude": 70.3131
}
}
]
}
This is the snippet of code I am using to try and access these values, but I am just testing getting "Name" for now:
String[] nodes = stringBuilder.toString().split("edges");
nodes[1] = "{" + "\"" + "edges" + nodes[1];
String s = nodes[1].substring(0,nodes[1].length()-3);
Log.d(TAG, s);
JSONObject json = new JSONObject(s);
JSONArray jsonArray = json.getJSONArray("edges");
ArrayList<String> allNames = new ArrayList<String>();
ArrayList<String> allLats = new ArrayList<String>();
ArrayList<String> allLongs = new ArrayList<String>();
for (int i=0; i<jsonArray.length(); i++) {
JSONObject node = jsonArray.getJSONObject(i);
Log.d(TAG, node.toString(1));
String name = node.getString("Name");
Log.d(TAG, name);
}
My output looks like this:
{"edges":[{"node":{"Name":"Sunday River","Latitude":44.4672,"Longitude":70.8472}},{"node":{"Name":"Sugarloaf Mountain","Latitude":45.0314,"Longitude":70.3131}}]}}
{
"node": {
"Name": "Sunday River",
"Latitude": 44.4672,
"Longitude": 70.8472
}
}
org.json.JSONException: No value for Name
I understand that I could use optString and not get the error, but that will not give me the data stored in each node.

Here is a version that works with your unaltered JSON:
public static void main(String... args)
{
String json = "{\"data\":{\"viewer\":{\"allMountains\":{\"edges\":[{\"node\":{\"Name\":\"Sunday River\",\"Latitude\":44.4672,\"Longitude\":70.8472}},{\"node\":{\"Name\":\"Sugarloaf Mountain\",\"Latitude\":45.0314,\"Longitude\":70.3131}}]}}}}";
JSONObject obj = new JSONObject(json);
JSONObject data = obj.getJSONObject("data");
JSONObject viewer = data.getJSONObject("viewer");
JSONObject allMountains = viewer.getJSONObject("allMountains");
// 'edges' is an array
JSONArray edges = allMountains.getJSONArray("edges");
for (Object edge : edges) {
// each of the elements of the 'edge' array are objects
// with one property named 'node', so we need to extract that
JSONObject node = ((JSONObject) edge).getJSONObject("node");
// then we can access the 'node' object's 'Name' property
System.out.println(node.getString("Name"));
}
}

How to access JSON data with multiple array objects : android

I am stuck in getting the data from the JSON file with multiple data sets.
{
"status": "ok",
"count": 3,
"count_total": 661,
"pages": 133,
"posts": [
{
"id": 20038,
"type": "post",
"slug": "xperia-launcher-download",
"url": "http:\/\/missingtricks.net\/xperia-launcher-download\/",
"status": "publish",
"title": "Download Xperia Launcher app for Android (Latest Version)"
},
{
"id": 94,
"type": "post",
"slug": "top-free-calling-apps-of-2014-year",
"url": "http:\/\/missingtricks.net\/top-free-calling-apps-of-2014-year\/",
"status": "publish",
"title": "Best Free Calling Apps for Android November 2014"
},
{
"id": 98,
"type": "post",
"slug": "top-free-calling-apps-of-2016-year",
"url": "http:\/\/missingtricks.net\/top-free-calling-apps-of-2016-year\/",
"status": "publish",
"title": "Best Free Calling Apps for Android December 2016"
}
]
}
I need to access the title, url and status from the above JSON file.
#Override
protected void onPostExecute(String result) {
//this method will be running on UI thread
pdLoading.dismiss();
List<DataFish> data = new ArrayList<>();
pdLoading.dismiss();
try {
JSONArray jArray = new JSONArray(result);
// Extract data from json and store into ArrayList as class objects
for (int i = 0; i < jArray.length(); i++) {
JSONObject json_data = jArray.getJSONObject(i);
DataFish fishData = new DataFish();
fishData.status = json_data.getString("status");
fishData.title = json_data.getString("url");
fishData.sizeName = json_data.getString("title");
data.add(fishData);
}
} catch (JSONException e) {
Toast.makeText(JSonActivity.this, e.toString(), Toast.LENGTH_LONG).show();
Log.d("Json","Exception = "+e.toString());
}
}
I am getting a JSONException with the above code.
What should I do to access the title,status and url from the JSON File?

You have to fetch your JSONArray which is inside a JSONObject , so create a JSONObject and fetch your array with index "posts"
1.) result is a JSONObject so create a JSONObject
2.) Fetch your JSONArray with index value as "posts"
3.) Now simply traverse array objects by fetching it through index
JSONObject jObj = new JSONObject(result);
JSONArray jArray = jObj.getJSONArray("posts");
// Extract data from json and store into ArrayList as class objects
for (int i = 0; i < jArray.length(); i++) {
JSONObject json_data = jArray.getJSONObject(i);
DataFish fishData = new DataFish();
fishData.status = json_data.getString("status");
fishData.title = json_data.getString("url");
fishData.sizeName = json_data.getString("title");
data.add(fishData);
}
Note : i don't know weather it is a sample response with shorter version though your json object should ends with } not with , .
[{"id":20038,"type":"post","slug":"xperia-launcher-download","url":"http://missingtricks.net/xperia-launcher-download/","status":"publish","title":"Download
Xperia Launcher app for Android (Latest Version)",
// ^^^ there should be a } not a , to end json
// so make sure to do the correction so it will look like => ...st Version)"},
{"id":94,"type":"post","slug":"top-free-calling-apps-of-2014-year","url":"http://missingtricks.net/top-free-calling-apps-of-2014-year/","status":"publish","title":"Best
Free Calling Apps for Android November 2014", ]
Improvements :
you can use optString to avoid null or non-string value if there is no mapping key
This has two variations
Get an optional string associated with a key. It returns the
defaultValue if there is no such key.
public String optString(String key, String defaultValue) {
fishData.status = json_data.optString("status","N/A");
// will return "N/A" if no key found
or To get empty string if no key found then simply use
fishData.status = json_data.optString("status");
// will return "" if no key found where "" is an empty string

You can validate your JSON here.
If entire JSON getJsonObject() is not working, then you should parse JSON objects & array in multiple arrays then use them.

How to decode JSONObject

This question is related with my previous question
I can successfully get the String in json format from the URL to my spring controller
Now I have to decode it
so I did like the following
#RequestMapping("/saveName")
#ResponseBody
public String saveName(String acc)
{jsonObject = new JSONObject();
try
{
System.out.println(acc);
org.json.JSONObject convertJSON=new org.json.JSONObject(acc);
org.json.JSONObject newJSON = convertJSON.getJSONObject("nameservice");
System.out.println(newJSON.toString());
convertJSON = new org.json.JSONObject(newJSON.toString());
System.out.println(jsonObject.getString("id"));
}
catch(Exception e)
{
e.printStackTrace();jsonObject.accumulate("result", "Error Occured ");
}
return jsonObject.toString();
}
This is the JSON String { "nameservice": [ { "id": 7413, "name": "ask" }, { "id": 7414, "name": "josn" }, { "id": 7415, "name": "john" }, { "id": 7418, "name": "RjhjhjR" } ] }
When I run the code then I get the error
org.json.JSONException: JSONObject["nameservice"] is not a JSONObject.
What wrong I am doing?

It's not a JSONObject, it's a JSONArray
From your question:
{ "nameservice": [ { "id": 7413, "name": "ask" }, { "id": 7414, "name": "josn" }, { "id": 7415, "name": "john" }, { "id": 7418, "name": "RjhjhjR" } ] }
The [ after the nameservice key tells you it's an array. It'd need to be a { to indicate an object, but it isn't
So, change your code to use it as a JSONArray, then iterate over the contents of that to get the JSONObjects inside it, eg
JSONArray nameservice = convertJSON.getJSONArray("nameservice");
for (int i=0; i<nameservice.length(); i++) {
JSONObject details = nameservice.getJSONObject(i);
// process the object here, eg
System.out.println("ID is " + details.get("id"));
System.out.println("Name is " + details.get("name"));
}
See the JSONArray javadocs for more details

It seems you're trying to get a JSONObject when "nameservice" is an array of JSONObjects and not an object itself. You should try this:
JSONObject json = new JSONObject(acc);
JSONArray jsonarr = json.getJSONArray("nameservice");
for (int i = 0; i < jsonarr.length(); i++) {
JSONObject nameservice = jsonarr.getJSONObject(i);
String id = nameservice.getString("id");
String name = nameservice.getString("name");
}

I don't understand why you do it manualy if you already have Spring Framework.
Take a look at MappingJackson2HttpMessageConverter and configure your ServletDispatcher accordingly. Spring will automatically convert your objects to JSON string and vice versa.
After that your controller method will be looked like:
#RequestMapping("/saveName")
#ResponseBody
public Object saveName(#RequestBody SomeObject obj) {
SomeObject newObj = doSomething(obj);
return newObj;
}

Nested JSONObject

I am having several problems with JSONObjects and JSONArray.
I would like to parse this json file:
[{
"SourceFile": "AndresIniesta.flv",
"ExifTool": {
"ExifToolVersion": 8.22
},
"System": {
"FileName": "AndresIniesta.flv",
(...)
},
"File": {
"FileType": "FLV",
"MIMEType": "video/x-flv"
},
"Flash": {
"Duration": "04:09",
"Starttime": 0,
"Totalduration": 249.36,
"ImageWidth": 320,
(...)
},
"Composite": {
"ImageSize": "320x240"
}
}]
But not all of them, just the field Flash.
The whole file is an JSONArray, but with just 1 element. I got the Flash filled with this piece of code:
JsonMappingException, IOException {
String a = new String();
InputStream is =
this.getClass().getClassLoader().getResourceAsStream(
"a.json");
String jsonTxt = IOUtils.toString(is);
JSONArray json = (JSONArray) JSONSerializer.toJSON(jsonTxt);
JSONObject flash = json.getJSONObject(0);
System.out.print("flash -> " + flash.getString("Flash"));
But I don't know hoy to access to each one of Flash fild, lis Duration, Starttime... etc.
When I try it like this:
String canseekontime =
flash.getString("Canseekontime");
int starttime =
flash.getInt("Starttime");
Double duration = flash.getDouble("Duration");
I get this error:
net.sf.json.JSONException: JSONObject["Duration"] not found.
Any help??
Thanks in advance

You mean
JSONObject flash = json.getJSONObject(0);
JSONObject Flash = flash.getJSONObject("Flash");
int starttime = Flash.getInt("Starttime");