Develop Reference

Parsing json error: java.lang.IllegalStateException: Not a JSON Object:

I am trying to parse a large json file which contains a bunch of cities (the following is the first two cities in the file):
[
{
"id": 707860,
"name": "Hurzuf",
"country": "UA",
"coord": {
"lon": 34.283333,
"lat": 44.549999
}
},
{
"id": 519188,
"name": "Novinki",
"country": "RU",
"coord": {
"lon": 37.666668,
"lat": 55.683334
}
} ]
I want to get the IDs of cities whose "name" value matches a String:
JsonParser parser = new JsonParser();
JsonElement jsontree = parser.parse(new FileReader("C:/Users/kevin/Eclipse-workspace-new/kevinzhou_CSCI201_assignment3/WebContent/city.list.json"));
JsonElement je = jsontree.getAsJsonObject();
JsonArray ja = je.getAsJsonArray();
for (Object o : ja)
{
JsonObject city = (JsonObject) o;
if(cityName == city.get("name").getAsString())
{
System.out.println(city.get("id").getAsString());
}
}
However, I am getting the following error : java.lang.IllegalStateException: Not a JSON Object:
and then it spits out the entire file after the colon.

change to
// JsonElement je = jsontree.getAsJsonObject();
JsonArray ja = jsontree.getAsJsonArray();
as it contains an Array at the top level

Try below given code to handle both condition
if (jsontree instanceof JsonObject) {
JsonObject jobject = new JsonObject(jsontree .getAsJsonObject());
} else if (jsontree instanceof JsonArray) {
JsonArray jarray = new JsonArray(jsontree .getAsJsonArray());
}

Return Java JsonPath as a json string

Using the java json path library: https://github.com/json-path/JsonPath
Given a json like this
{
"store": {
"book": [
{
"category": "reference"
},
{
"category": "fiction"
}
],
"bicycle": {
"color": "red",
"price": 19.95
}
},
"expensive": 10
}
I would like to return "book" as a list of strings. For examples:
List<String> results = JsonPath.read(example, "$.store.book[*]");
And results should look like:
["{\"category\":\"reference\"}", "{\"category\":\"fiction\"}"]
Is there a way to achieve this?
Currently:
System.out.println(udf.jsonExtractScalar(testExample, "$.store.book[*]").getClass().getName());
--> net.minidev.json.JSONArray

As book is a JsonArray in you json tree, you can use JsonArray type and retrieve the data from it and add to the list.
Here is an example.
JSONArray jsonArray = new JSONArray(jsonArrayString);
List<String> list = new ArrayList<String>();
for (int i=0; i<jsonArray.length(); i++) {
list.add( jsonArray.getString(i) );
Replace jsonArrayString with you jsondata's books array name and you will be good to go.
The class used will be JSONArray class which is
`org.json.JSONArray`

How to dynamically simplify json using java?

I have received a json string like so:
{
"data": [
{
"name": "Order",
"value": "2"
},
{
"name": "Address",
"value": "182"
},
{
"name": "DNS",
"value": "null"
},
{
"name": "SSID",
"value": "work"
},
{
"name": "Protocol",
"value": "0"
},
{
"name": "Key",
"value": ""
},
{
"name": "carrier",
"value": "undefined"
},
{
"name": "SSH",
"value": "1"
},
{
"name": "ntp_addr",
"value": ""
},
{
"name": "Name",
"value": ""
}
]
}
I used stringify on an html response and this is what I have to parse. As you can see, it is pretty redundant; I would much rather { "Order":"2" } than { "name":"Order","value":"2" } ... So an array of name-value pairs, instead of an array of objects.
Is there a way I can dynamically format this response so that it will be easier to parse?
What 'd like is to be able to say:
JSONObject jsonObject = new JSONObject(jsonResponse);
JSONArray data = jsonObject.getJSONArray("data");
for (int i = 0; i < data.length(); i++) {
JSONObject dataObject = data.getJSONObject(i);
String order = dataObject.getString("Order");
String address = dataObject.getString("Address");
// etc...
}
But the current format makes it almost impossible to parse. I'd need loops within loops.

I'd like to use com.google.gson library. And this response easy to parse with it:
private final JsonParser PARSER = new JsonParser();
public void parse(String jsonString) {
JsonObject dataObject = PARSER.parse(jsonString).getAsJsonObject();
JsonArray dataArray = dataObject.get("data").getAsJsonArray();
dataArray.iterator().forEachRemaining(element -> {
String name = element.getAsJsonObject().get("name").getAsString();
String value = element.getAsJsonObject().get("value").getAsString();
}
}
Or you can simply use TypeAdapters for json deserialization directly in the object.

Something like this should do the trick
JSONObject jsonObject = new JSONObject(jsonResponse);
JSONArray data = jsonObject.getJSONArray("data");
JSONObject simplifiedDataObject = new JSONObject();
for (int i = 0; i < data.length(); i++) {
JSONObject dataField = data.getJSONObject(i);
simplifiedDataObject.put(dataField.getString("name"), dataField.get("value"));
}
You just iterate over each element in data, use the name field as the field on a new JSONObject and simply retrieve the value using the value key.

Class cast exception [JSONArray cannot be cast to org.json.simple.JSONObject]

I have a json file like this
[ {
"id":"serve-coffee",
"tags":[ {
"name": "#tag1", "line": 1
}
],
"description":"Coffee should not be served\n",
"name":"Serve coffee",
"keyword":"Feature",
"line":2,
"elements":[ {
"id": "serve-coffee;buy-last-coffee", "tags":[ {
"name": "#tag2", "line": 6
}
],
"description":"",
"name":"Buy last coffee",
"keyword":"Scenario",
"line":7,
"steps":[ {
"name": "there are 1 coffees left in the machine", "keyword": "Given ", "line": 8
}
,
{
"name": "I have deposited 1$", "keyword": "And ", "line": 9
}
],
"type":"scenario"
}
],
"uri":"src\/test\/resources\/traffic-remove-locations.feature"
}
]
Iam trying to convert the above json file to JSONObject.But am getting class cast exception "java.lang.ClassCastException: org.json.simple.JSONArray cannot be cast to org.json.simple.JSONObject"
code
public static JSONObject convertFileToJSON(String fileName) throws ParseException {
// Read from File to String
JSONParser parser = new JSONParser();
JSONObject jsonObject = null;
try {
Object object = parser.parse(new FileReader(fileName));
jsonObject = (JSONObject) object; // Getting classCast Exception here.
} catch (FileNotFoundException e) {
} catch (IOException ioe) {
}
return jsonObject;
}
but when i changed the line jsonObject = (JSONObject) object; to JSONArray jsonArray = (JSONObject)object the exception disappears.
But if am casting to JSONArray then how can i get the values like id,tags and description from JSONArray.
please provide a suggestion guys

Your JSON file represents an array with one object in it. So if that were a Java data structure, you're effectively doing this:
int[] arr = {5};
int i = (int)arr;
This obviously doesn't work because you can't cast an array to a singular object. What you actually want to do it pull out the first element of the array. To continue the Java example, you want to do
int[] arr = {5};
int i = (int)arr[0];
With the JSON stuff, your parser.parse() call returns a JSONArray, not a JSONObject. So you'll need to do something like this:
public static JSONObject convertFileToJSON(String fileName) throws ParseException {
JSONParser parser = new JSONParser();
JSONObject jsonObject = null;
try {
JSONArray array = (JSONArray) parser.parse(new FileReader(fileName));
jsonObject = array.getJsonObject(0);
} catch (FileNotFoundException e) {
} catch (IOException ioe) {
}
return jsonObject;
}

Try casting to JsonArray and then cast access the objects one by one with help of the index from the JSON array.
Object object = parser.parse(new FileReader(fileName));
JsonArray jsonArr = (JsonArray) object; // Getting c
jsonObject jsonObj = jsonArr.get(0); //use index to access like a list

I was also facing the same issue. I did the below changes to make it work.
Below is my sample JSON.
{
"routes": [{
"startTime": 1520319414,
"routeInfo": [{
"routePart": 0,
"transType": "WALK",
"transDetails": {
"startLoc": {
"lat": 28.6434862,
"lon": 77.22542659999999
}
}
}, {
"routePart": 1,
"transType": "BUS",
"transDetails": {
"routeNumber": "307-U",
"interStopDetails": [{
"seq": 1,
"name": "test1",
"loc": {
"lat": 28.64302,
"lon": 77.2260367
},
"eta": 1520319600
}
]
}
}
],
"totalTime": 5742
}
]
}
Solution to Parse:
JSONObject obj = (JSONObject) jsonParser.parse(new FileReader(FilepathDummy));
JSONArray jsonRoutes= (JSONArray) obj.get("routes"); //Gives Main JSoN
JSONObject routeJsonObject = (JSONObject) jsonRoutes.get(0); // Route Array into JSON
JSONArray routeInfoArray = (JSONArray) routeJsonObject.get("routeInfo"); // RouteInfo Array
Hope this solve your problem.

Accessing json string in java and creating hashmap Android

I have a JSON string and I am trying to retrieve information from it. Json String looks like this.
JSON STRING :
{
"information": {
"device": {
"id": 0
},
"user": {
"id": 0
},
"data": [
{
"datum": {
"id": "00GF001",
"history_id": "9992BH",
"name": "abc",
"marks": 57,
"class": "B",
"type": "Student"
}
},
{
"datum": {
"id": "72BA9585",
"history_id": "78NAH2",
"name": "ndnmanet",
"marks": 70,
"class": "B",
"type": "Student"
}
},
{
"datum": {
"id": "69AHH85",
"history_id": "NN00E3006",
"name": "kit",
"department": "EF003",
"class": "A",
"type": "Employee"
}
},
{
"datum": {
"id": "09HL543",
"history_id": "34QWFTA",
"name": "jeff",
"department": "BH004",
"class": "A1",
"type": "Employee_HR"
}
}
]
}
}
I am trying to access data JSONArray and respective Datum from it. I differentiated each datum as per type such as student, employee etc and push information in hashmap.
I successfully did it in javascript but in Java I am struggle abit.
When I am trying to access JSONArray it throws exception
try {
JSONObject data = new JSONObject(dataInfo);
// Log.d(TAG, "CHECK"+data.toString());
JSONObject info = data.optJSONObject("information");
if(info.getJSONArray("data").getString(0).equals("Student") > 0) //exception here
Log.d(TAG, "Data"+ data.getJSONArray("data").length()); //exception here too
for(int m = 0; m < data.length(); m++){
// for(int s = 0; s < data[m].ge)
}
} catch (JSONException j){
j.printStackTrace();
}
Any pointers to create hashmap respective type I have. Appreciated

If you're trying to access the type field of a datum object, you'll want something like this:
JSONObject data = new JSONObject(dataInfo); // get the entire JSON into an object
JSONObject info = data.getJSONObject("information"); // get the 'information' object
JSONArray dataArray = info.getJSONArray("data"); // get the 'data' array
for (int i = 0; i < dataArray.length(); i++) {
// foreach element in the 'data' array
JSONObject dataObj = dataArray.getJSONObject(i); // get the object from the array
JSONObject datum = dataObj.getJSONObject("datum"); // get the 'datum' object
String type = datum.getString("type"); // get the 'type' string
if ("Student".equals(type)) {
// do your processing for 'Student' here
}
}
Note that you'll have to deal with exception handling, bad data, etc. This code just shows you the basics of how to get at the data that you're looking for. I separated each individual step into its own line of code so that I could clearly comment what is happening at each step, but you could combine some of the steps into a single line of code if that is easier for you.

if dataInfo is the json you posted, then you have to access information and from information, you can access data:
JSONObject data = new JSONObject(dataInfo);
JSONObject info = data.optJSONObject("information");
if (info != null) {
JSONArray dataArray = info.optJSONArray("data")
}