We Keep Coding

Reading element one by one in JsonArray

I have below JSON returned by API call.
String jsonString="{\r\n" +
" \"count\": 100,\r\n" +
" \"limit\": 100,\r\n" +
" \"totalResults\": 225,\r\n" +
" \"hasMore\": true,\r\n" +
" \"items\": [\r\n" +
" {\r\n" +
" \"id\": \"55D40522-8672-48B0-B225-FD3CE6686AD6\",\r\n" +
" \"name\": \"AcmeHCMExtended\",\r\n" +
" \"version\": \"20.01.01.03\",\r\n" +
" \"status\": \"DRAFT\"\r\n" +
" },\r\n" +
" {\r\n" +
" \"id\": \"2DB4C83B-0CF9-4A8E-AC41-A29B30324121\",\r\n" +
" \"name\": \"AFinancialBot\",\r\n" +
" \"version\": \"1.0\",\r\n" +
" \"status\": \"DRAFT\"\r\n" +
" },\r\n" +
" {\r\n" +
" \"id\": \"7EA85B81-3CA1-4BE0-B095-217E7C93DCEF\",\r\n" +
" \"name\": \"AIAMFG\",\r\n" +
" \"version\": \"1.0\",\r\n" +
" \"status\": \"DRAFT\"\r\n" +
" }"
I want to read name one by one under the itmes. I am using below code.
JsonObject obj=Json.parse(jsonString).asObject();
JsonArray items=obj.get("items").asArray();
System.out.println(items); //it prints everything under items.
`System.out.println(items.name); ` //It gives error
I am not able to iterate item array. it does not show length property of array.
Can you guide me how can I access element one by one.

It looks like you are using the javax.json.JsonArray APIs or something similar. If so:
JsonArray items = obj.get("items").asArray();
for (int i = 0; i < items.size(); i++) {
System.out.println(items.getJsonObject(i));
}
Note that JsonArray implements java.util.List and you are getting the size using the standard List API method.
The same code would work with com.google.gson.JsonArray ... though this class does NOT implement List. Alternatively, you could make use of the fact that com.google.gson.JsonArray implements Iterable and write a "for each" loop:
for (JsonElement e: items) {
System.out.println(e);
}
The equivalent code for org.json.JSONArray uses length() instead of size().
In all cases, you should be able to answer your own question by searching for and reading the javadocs for the JSON library that you are using.
UPDATE - Apparently you are using the com.eclipsesource.minimal-json. According to this javadoc, it has a size() method and implements Iterable.

How to parse custom objects from a list within a jsonstring?

I got the following json:
{
"ID": "1234567",
"dangereousCargo": true,
"numberOfPassangers": 164,
"cargo": [
{
"type": "Oil",
"amount": 8556
},
{
"type": "Chemicals",
"amount": 5593
}
]
}
From this question, I understood that it is possible to get the cargoList out of the jsonObject (if that list contains a certain type of object). But how do I get the seperate cargoObjects out of that list?
+Do the variable names of the jsonstring have to correspond with the variable names in my CargoClass? What if the jsonObject only contains type and amount and my CargoClass has more attributes?

You can iterate throws the JSONArray which represents your cargo list doing (not tested)
JSONObject json = new JSONObject(jsonString);
JSONArray cargoList = json.getJSONArray("cargo");
for(int i=0; i< cargoList.length(); i++) {
JSONObject cargo = cargoList.getJSONObject(i);
//Do something with cargo
}

But how do I get the seperate cargoObjects out of that list?
String jsonString = "{ ... }";
JSONObject json = new JSONObject(jsonString);
JSONArray cargoList = json.getJSONArray("cargo");
for(JSONObject cargo : cargoList)
{
//do something with your cargo element
}
Do the variable names of the jsonstring have to correspond with the
variable names in my CargoClass?
If you use the the get method from the JSONObject, you have to specify the exact name of the attribute in your jsonString. Following the example above:
String cargoType = cargo.getString("type");
By the way, if you want to use your already defined CargoClass, you need a Deserializer and all the attributes on your JSON must be the all present and all the same on your CargoClass: I suggest you to take a look at other SOs questions like this one.
What if the jsonObject only contains type and amount and my CargoClass
has more attributes?
The other attributes will be initialize in base of your class declaration

Using JSON Simple it is very easy to parse and read your data from your JSON. As other users have said there are a plethora of libraries out there that can accomplish this. Below is a tested example of your code.
public static void main(String[] args) throws JSONException {
String json = "{\n"
+ " ID: 1234567,\n"
+ " dangereousCargo: true,\n"
+ " numberOfPassangers: 164,\n"
+ " cargo: [\n"
+ " {\n"
+ " type: Oil,\n"
+ " amount: 8556\n"
+ " },\n"
+ " {\n"
+ " type: Chemicals,\n"
+ " amount: 5593\n"
+ " }\n"
+ " ]\n"
+ "}";
JSONObject data = new JSONObject(json);
int id = data.getInt("ID");
boolean danger = data.getBoolean("dangereousCargo");
int numOfPassengers = data.getInt("numberOfPassangers");
System.out.println("Current ID: " + id + "\n"
+ "Is Dangerous: " + danger + "\n"
+ "Number of Passengers: " + numOfPassengers + "\n");
JSONArray cargo = data.getJSONArray("cargo");
NumberFormat currency = NumberFormat.getCurrencyInstance();
for (int i = 0; i < cargo.length(); i++) {
JSONObject cargoObject = cargo.getJSONObject(i);
String type = cargoObject.getString("type");
double amount = cargoObject.getDouble("amount");
System.out.println("Current Type: " + type);
System.out.println("Current Amount: " + currency.format(amount));
}
}
}
The above code gives us the following output:
Once you have your data you can really do whatever you want with it.
Libraries
JSONSimple-https://code.google.com/p/json-simple/
GSON-https://github.com/google/gson

URL in JSON object as POST request Android

Please help me to send a JSON object in POST HTTP request through HttpClient, in Android.
The problem I am facing is that the JSON object having the URL is replaced by forward slash ,i.e
originally it should have the following value in JSON object
{"product":
{"featured_src":"https:\/\/example.com\/wp-content\/uploads\/2015\/06\/sidney-compressed.jpg,
"short_description":"this is a test","title":"Raiders from the North"}
}
i tried many options to keep it in the above format. But it always comes as {"featured_src":

We assume this is your input
private final static String JSON_DATA = "{"
+ " \"product\": ["
+ " {"
+ " \"featured_src\": \"https:\\/\\/example.com\\/wp-content"
+ "\\/uploads\\/2015\\/06\\/sidney-compressed.jpg\","
+ " \"short_description\": \"this is a test\","
+ " \"title\" : \"Raiders from the North\""
+ " }"
+ " ]"
+ "}";
You could use replace to do the trick.
YOUR_STRING.replace("\\", "");
Finally your method would look like this, by passing your string as parameter
private static String jsonUrlCorrector(String json_data) {
json_data = json_data.replace("\\", "");
return json_data;
}
Here is the input:
{"product":[{"featured_src":"https:\/\/example.com\/wp-content\/uploads\/2015\/06\/sidney-compressed.jpg","short_description": "this is a test","title":"Raiders from the North"}]}
Here is the output
{"product":[{"featured_src":"https://example.com/wp-content/uploads/2015/06/sidney-compressed.jpg","short_description":"this is a test","title":"Raiders from the North"}]}

Spring RestTemplate jackson fetch particular field

I have the following JSON in my android application and I'm using Springs for android RestTemplate. Is it somehow possible to fetch only internal list from this json ? Currently I have to create a wrapper object and then I can fetch List<Cast> casts; from it - it's a bit inconvenient.
{
"id": 550,
"cast": [
{
"cast_id": 4,
"character": "The Narrator",
"credit_id": "52fe4250c3a36847f80149f3",
"id": 819,
"name": "Edward Norton",
"order": 0,
"profile_path": "/iUiePUAQKN4GY6jorH9m23cbVli.jpg"
}
]
}

I know two solutions to solve this :
What you've done : Wrapping the list using a class
Write you're own JSON Deserializer, take a look here http://wiki.fasterxml.com/JacksonHowToCustomDeserializers
But I think the ultimate solution is in this post:
Spring/json: Convert a typed collection like List<MyPojo>

If Cast is a POJO you could try use the Jackson ObjectMapper class like this
ObjectMapper mapper = new ObjectMapper();
String jsonStr = ...
List<Cast> casts = mapper.readValue(jsonStr, new TypeReference<List<Cast>>(){});

You can grab the field, cast, and convert it like so:
final String json = "{\n" +
" \"id\": 550,\n" +
" \"cast\": [\n" +
" {\n" +
" \"cast_id\": 4,\n" +
" \"character\": \"The Narrator\",\n" +
" \"credit_id\": \"52fe4250c3a36847f80149f3\",\n" +
" \"id\": 819,\n" +
" \"name\": \"Edward Norton\",\n" +
" \"order\": 0,\n" +
" \"profile_path\": \"/iUiePUAQKN4GY6jorH9m23cbVli.jpg\"\n" +
" }\n" +
" ]\n" +
"}";
final List<Cast> casts;
try {
final JsonNode cast = objectMapper.readTree(json).get("cast");
casts = objectMapper.convertValue(cast, new TypeReference<List<Cast>>() {});
} catch (IOException e) {
throw Throwables.propagate(e);
}

Parsing a json object with an unknown name with gson

{
"lastUpdated":1404620562,
"invasions":{
"Vibrant Valley":{
"asOf":1404620562,
"type":"Penny Pincher",
"progress":"959/1000"
}
},
"error":null
}
I'm new to using Json & Gson so be patient.
So I am attempting to make an application for myself that allows me to view the information from this json file. The only problem is that it is constantly changing and sometimes there will be more then one object under invasions or sometimes there will be none. How would I parse this with gson? Thanks. Note I am grabbing values from here.
https://www.toontownrewritten.com/api/invasions
Thanks!

Use the JsonParser class
String myJson = "{" +
" \"lastUpdated\":1404620562," +
" \"invasions\":{" +
" \"Vibrant Valley\":{" +
" \"asOf\":1404620562," +
" \"type\":\"Penny Pincher\"," +
" \"progress\":\"959/1000\"" +
" }" +
" }," +
" \"error\":null" +
"}"
JsonElement jelement = new JsonParser().parse(myJson);
JsonObject jobject = jelement.getAsJsonObject();
long lastUpdated = jobject.get("lastUpdated").getAsLong();