Develop Reference

JSON Object empty when creating it from a String

I'm trying to create a JSON Object from a String. The String looks like this: {"case":"getAllProducts"}.
Why is jobj always empty?
String received = textMessage.getText();
System.out.println(received); //{"case":"getAllProducts"} - perfect
JsonObject jobj = new Gson().fromJson(received, JsonObject.class);
System.out.println(jobj); //{} - why empty???
String reqCase = jobj.get("case").getAsString();
I already checked out other articles here where its done exactly like I did. I can't find my problem here..

Instead of
new Gson().fromJson(received, JsonObject.class);
it should be
new Gson().fromJson(received, YourClass.class);
where YourClass is a user defined class having attributes same as the attributes in your JSON.

Parse JSON file in Java: getJSONObject(int) is undefined

I`m trying to fetch some values fron a JSON file using:
JSONParser parser = new JSONParser();
Object obj = parser.parse(new FileReader("C:\\myfile.json"));
JSONArray array= new JSONArray();
array.add(obj);
If I run: System.out.println(array); , the output is
[{"flowrate":{"mod":0,"value":110},"command":{"cancel":0,"start":0}}]
, which is my json file.
My problem is how to get value from a specific field, let's say the value of "comand":"cancel".
I've tried JSONObject myitem = array.getJSONObject(1).getJSONObject("cancel"); with no success (error: getJSONObject(int) is undefined for the type JSONArray).
I mention that I'm using the json-simple toolkit.

I also could not validate your JSON. I made an assumption that you wanted to create an array of two objects (flowrate and command) and fixed the JSON:
String value = "[{\"flowrate\":{\"mod\":0,\"value\":110}},{\"command\":{\"cancel\":0,\"start\":0}}]";
JSONParser parser = new JSONParser();
Object obj = parser.parse(value);
JSONArray array=(JSONArray)obj;
JSONObject jo = (JSONObject) array.get(1);
System.out.println(jo.get("command"));
which gives the following output:
{"cancel":0,"start":0}
Process finished with exit code 0

After many hours of searching, I discovered that there is big difference between { } and [ ], therefore differnent methodes to parse them:
In my case:
JSONParser parser = new JSONParser();
Object obj = parser.parse(new FileReader("C:\\myfile.json"));
JSONObject jsonObject = (JSONObject) json;
JSONObject command= (JSONObject) jsonObject.get("command");
System.out.println("command: " + command);
long cancel= (Long) command.get("cancel");
System.out.println("cancel: " + cancel);
Here you'll find the best example for nested json objects

Parser for json Object in java

I am trying to create a common parser in java.I am passing json object from different class based on my need.But parsing doesnot works for me.Can anybody help me to make a JSONObject parser in java.Any help will be highly appreciable....
This is my code for common parser
public JSONObject jsonParser(JSONObject objJson){
//JSONObject myjson = new JSONObject(objJson);
JSONArray the_json_array = objJson.getJSONArray("profiles");
JSONObject SnapshotRequest= objJson.g;
Iterator x = SnapshotRequest.keys();
JSONArray jsonArray = new JSONArray();
while (x.hasNext()){
String key = (String) x.next();
jsonArray.put(songs.get(key));
}
}
In this code I am getting an error that need to cast.
JSONArray the_json_array = objJson.getJSONArray("profiles");
But casting won't work.

Java:how to parse this json

I want to parse this json to retrieve the value of tel or user_id
For example:
{
"status":"ok",
"account":{
"0":{
"user_id":"2",
"thirdparty_id":"200",
"tel":"28000000",
"mobile":"28000000",
"fax":"28000000"
}
}
}
Here is the code I am attempting to use to retrieve tel:
JsonParser jp = new JsonParser();
JsonElement root = jp.parse(new InputStreamReader((InputStream) request.getContent()));
JsonObject rootobj = root.getAsJsonObject();
JsonObject rootobj1 = (JsonObject) rootobj.get("account");
JsonObject rootobj2 = (JsonObject) rootobj.get("0");
String tel=rootobj2.get("tel").getAsString();
The problem is that a java.lang.NullPointerException is thrown at this line :
String tel=tel=rootobj2.get("tel").getAsString();

First thing if you have post the JsonString correctly then it is not a valid json as tel" should be "tel"
Then you can parse it using org.json as
JSONObject jsonObject = new JSONObject(str);
JSONObject json1 = new JSONObject(jsonObject.get("account").toString());
JSONObject json2 = new JSONObject(json1.get("0").toString());
System.out.println(json2.get("user_id").toString());

You have two problems. First, you are not actually descending the tree. Initialize rootobj2 like this:
JsonObject rootobj2 = (JsonObject) rootobj1.get("0"); // NOT rootobj.get("0");
Second, once rootobj2 is initialized correctly, it will not have an attribute "0". Try this:
String tel=rootobj2.get("tel").getAsString(); // NOT rootobj2.get("0").getAsString();

parsing URL in String from JSON

1) I've got a JSON file:
{
"serverURI":"http://localhost:8080/PocketUNI_API/serverURLs",
"newsURI":"http://localhost:8080/gateway/rss/rss.xml",
"modulesURI":"http://localhost:8080/PocketUNI_API/modules"
}
2) I need to get URLs on Java client in String format.
String json = jsonReceiver.makeHttpRequest(URL_SERVER, "GET", params);
JSONArray uris = new JSONArray(json);
Receiver works fine and json shows the correct string received, but when it goes to parsing with JSONArray it throws an error
org.json.JSONException: Value {"serverURI":"http:\/\/192.168.0.... of type org.json.JSONObject cannot be converted to JSONArray.
Question: How to parse json with URL values?

You don't get a JSONArray but a JSONObject.
JSONObject uris = new JSONObject(json);

json is a json object not an array, that is why you are getting the error. An array will be wrapped with in [ and ], and objects within { and }.
JSONObject uris = new JSONObject (json);

Instead of JSONArray you must use JSONObject.
JSONObject uris = new JSONObject(json);

In your code just replace JSONArray to JSONobject
JSONObject uris = new JSONObject(json);