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Loop through json file appending key value to List

I am trying to loop through a JSON file and append the value each time to patientList. So far I believe I have done the hard part, however the simplest part seems to be taking a lot of time, that is appending the values to patientList. My getJsonFile method gets the path of the JSON file. The format of the JSON file is below. I am able to print jsonArray so I know I am good up to that point, but lost after that.
Json file.
[{"patient":1},{"patient":2},{"patient":3},{"patient":4},{"patient":5},{"patient":6},{"patient":7},{"patient":8},{"patient":9}]
getJsonFile method.
private List<Integer> getJsonFile(String path)
{
List<Integer> patientList = new ArrayList<>();
try (FileReader reader = new FileReader(path))
{
JSONParser jsonParser = new JSONParser();
JSONArray jsonArray = (JSONArray)jsonParser.parse(reader);
System.out.println(jsonArray);
// Update patientList
for (int i = 0; i < jsonArray.size(); i++ )
{
patientList.add(jsonArray(i));
}
}
catch(IOException | ParseException | NullPointerException e)
{
e.printStackTrace();
}
return patientList;
}

Your JSONArray contains objects: {"patient":1}
So you could not add patientList.add(jsonArray(i));
You have to access the int value inside that object:
JSONObject patient = jsonArray.getJsonObject(i);
patientList.add(patient.getInt("patient");
Edit
Well. You are using the simple-json library with quite limit feature and outdated. In this case you have to cast the data yourself:
JSONObject patient = (JSONObject)jsonArray.get(i);
patientList.add((Integer)patient.get("patient");
I recommend you remove this lib and use existing JSON feature of Java. If you want more advance feature, Jackson/GSon is the library to use.

Why can't I instantiate a JSONObject in Java (string cannot be converted to map)

I am reading a Stackoverflow post (here), I am writing the code contained in the answer but I can't instantiate a JSONObject. The post don't specify where JSONObject comes from so imported it as follows:
import org.json.simple.JSONObject;
String jsonData = response.body().string();
JSONObject json = new JSONObject(jsonData); //jsonData marked as the soruce of the error and the message "incompatible types cannot convert string to map" shows.

You probably want org.json.JSONObject. That one has a constructor that takes a String.

Getting java object back from JSON

I am putting some java objects in the Json at server side
like this :
ArrayList<VisjsNode>visjsNodes = new ArrayList<VisjsNode>();
ArrayList<VisjsConnection> visjsConnections = new ArrayList<VisjsConnection>();
String jsondata = null;
org.json.JSONObject object = new org.json.JSONObject();
try {
object.put("nodes", visjsNodes);
object.put("connections", visjsConnections);
jsondata = object.toString();
Now is there a way I can get these objects back from this json (jsondata) at client side
I am doing this:
com.google.gwt.json.client.JSONValue jsonValue = JSONParser.parseStrict(jsondata);
com.google.gwt.json.client.JSONObject jsonObject = jsonValue.isObject();
jsonValue = jsonObject.get("nodes");
Now I am trying this to get ArrayList back , by doing this
ArrayList<VisjsNode>visjsNodesFromjson = jsonValue ;
But its not compiling ,it says Incompatable types...
Can you please guide how we can retrieve the Java Object back from Json ..

That's because you're using two different JsonObject class. First you use the one which comes from org.json (org.json.JsonObject) and the other is com.google.gwt.json.client.JSONObject. Nevertheless, they're named similar, they're completely different classes.

How to parse internal JSON elements?

I'm using json-simple-1.1.1.jar which was referred by tutorialpoint.com.
My JSON file is shown here:
My java code is here:
I couldn't understand how I would access "onclick": "CloseDoc()" in my JSON file.
If I use the getObject method it is showing me an error:
The method getJSONObject(String) is undefined for the type JSONObject

onClick is inside the array menuitem which is inside the object menu , so you have to loop the array to retrieve what you want. You can try it like this:
JSONParser parser = new JSONParser();
Object obj = parser.parse(new InputStreamReader(in));
String json_str = obj.toString();
JSONObject j_org_json_obj = new JSONObject(json_str);
JSONArray j_org_json_arr = j_org_json_obj.getJSONObject("menu").getJSONArray("menuitem");
for(int i=0;i<j_org_json_arr.length();i++)
{
System.out.println(j_org_json_arr.getJSONObject(i).getString("onClick()"));
}
Along with json-simple jar ,In the above code one more jar is included : org-json jar , so import that as well.

maybe you could check the import is org.json.simple.JSONObject
but this jar is not had a method call getJsonObject.

JAVA JSONObject parsing issue

I am using JSONObject to parse nested JSON from an API example:
{"results":[{"congress":"112","state":"NJ","num_results":"2","offset":"0","members": [{"id":"L000123","first_name":"Frank"..........................
I am having trouble accessing the members nested area using JSONObject.
This is my code, any thoughts?
url= new URL("http://api.nytimes.com/svc/politics/v3/us/legislative/congress/112/senate/members.json?&state=NJ&api-key=7967107ef3c9e8d6c2f560027f87904e:17:65990356");
ByteArrayOutputStream urlOutputStream = new ByteArrayOutputStream();
IOUtils.copy(url.openStream(), urlOutputStream);
String urlContents = urlOutputStream.toString();
// parse the JSON object returned
JSONObject jsonO = new JSONObject(urlContents);
System.out.println(jsonO.toString());
JSONObject results = jsonO.getJSONObject("results");
JSONObject senators = results.getJSONObject("members");

You should use third party library like GSON.
http://code.google.com/p/google-gson/