Json object to java arraylist - java

I have pass two values from ajax to my servlet.
I used
JsonObject data = new Gson().fromJson(request.getReader(), JsonObject.class);
System.out.println(data);
and this is the output
{"0":"31/01/2017","1":"19/01/2017"}
Now I want to convert this data into a java arraylist but not really sure how.
I tried
Gson googleJson = new Gson();
JsonObject data = googleJson.fromJson(request.getReader(), JsonObject.class);
System.out.println(data);
JsonArray jsonArr = data.getAsJsonArray();
// jsonArr.
ArrayList jsonObjList = googleJson.fromJson(jsonArr, ArrayList.class);
for(int i=0; i< jsonObjList.size(); i++) {
System.out.println(jsonObjList.get(i));
}
But got an error
java.lang.IllegalStateException: This is not a JSON Array.
Someone help me please? thanks.


Create instance of JsonArray then add json element to that array using key.
Here is your solution :
Gson googleJson = new Gson();
JsonObject data = googleJson.fromJson(request.getReader(), JsonObject.class);
System.out.println(data);
JsonArray jsonArr = new JsonArray();
for(Entry<String, JsonElement> entry : data.entrySet()) {
jsonArr.add(data.get(entry.getKey()));
}
ArrayList jsonObjList = googleJson.fromJson(jsonArr, ArrayList.class);
for(int i = 0; i < jsonObjList.size(); i++) {
System.out.println(jsonObjList.get(i));
}


For a Json to be a valid JsonArray object you should have it to a proper format. Can you change your json string return from your ajax? If yes you should change it to something like this:
Gson googleJson = new Gson();
JsonObject data = googleJson.fromJson("{test: [{\"0\":\"31/01/2017\"},{\"1\":\"19/01/2017\"}]}", JsonObject.class);
System.out.println(data);
JsonArray jsonArr = data.getAsJsonArray("test");
ArrayList jsonObjList = googleJson.fromJson(jsonArr, ArrayList.class);
for(int i=0; i< jsonObjList.size(); i++) {
System.out.println(jsonObjList.get(i));
}
If not you should parse it by your self and convert it to everything you want.

Related

Converting string to JSONArray, and then to list

I have String "[{...}]" and I want convert it to JSONArray, and then to List list = new List I was trying this solution, and this is my code
public void RestoreData()
{
String toConvert = "[{...}]" // I don't place full String, but it's typical JSONArray, but in String
ArrayList<myClass> listdata = new ArrayList<myClass>();
JsonObject jsonObject = new JsonObject();
JSONArray jArray = (JSONArray)jsonObject;
if (jArray != null) {
for (int i=0;i<jArray.length();i++){
listdata.add(jArray.getString(i));
}
}
}
And when I'm trying to compile this I get 2 errors:
In JSONArray jArray = (JSONArray)jsonObject; I get error 'Incovertible types; cannot cast 'org.json.JSONObject' to 'org.json.JSONArray'.
And second: in listdata.add(jArray.getString(i)); I get error 'unhandled exception org.json.JSONException'.
I'm new in Java and I work with Json for the first time.
EDIT
A small truncated example of the Json string:
[{"lootArmorGain":0,"lootBlockGain":0,"lootCost":93500,"lootCritGain":2,"lootCritPowerGain":0,"lootDamageAbsorptionGain":0,"lootDamageGain":0,
}]

I think what you want is:
public void RestoreData()
{
try{
String toConvert = "[{...}]" // I don't place full String, but it's typical JSONArray, but in String
ArrayList<MyClass> listdata = new ArrayList<MyClass>();
JSONArray jsonArray = new JSONArray(toConvert);
if (jsonArray != null) {
Gson gson = new Gson();
for (int i=0;i<jsonArray.length();i++){
String json = jsonArray.getJSONObject(i).toString();
MyClass obj = gson.fromJson(json, MyClass.class);
listdata.add(obj);
}
}
}catch(JSONException e){
e.printStackTrace();
}
}
To convert from JSONOject to your custom class use GSON, see above.
compile 'com.google.code.gson:gson:2.8.4'
Note that your custom class need to have an empty constructor as well as getters and setters in order to make gson work.

I think best approach will be using Google Gson Library.
String toConvert = "[{...}]"
Type listType = new TypeToken<List<myClass>>() {}.getType();
List<myClass> yourList = new Gson().fromJson(toConvert, listType);
You dont need to get each position manually.

For simplicity you can also use Jackson api
ObjectMapper objectMapper = new ObjectMapper();
TypeFactory typeFactory = objectMapper.getTypeFactory();
List<SomeClass> someClassList = objectMapper.readValue(jsonString,typeFactory.constructCollectionType(List.class, SomeClass.class));

Can't parse some JSON into a JsonArray using GSON

I am trying to get the values from a JSON response. I got everything to work, except extracting an array from the following string:
{"o":"1.18988","h":"1.18993","l":"1.18963","c":"1.18993"}
I know GSON is trying to parse it because I get this error:
Exception in thread "main" java.lang.IllegalStateException: Not a JSON Array: {"o":"1.18988","h":"1.18993","l":"1.18963","c":"1.18993"}
I am using the following code to attempt to parse it:
final JsonElement midElement = obj.get("mid");
final JsonArray midArray = midElement.getAsJsonArray();
for(Object rate : midArray){
final JsonObject rateObj = (JsonObject)rate;
final JsonElement openElement = rateObj.get("o");
open = openElement.getAsFloat();
final JsonElement highElement = rateObj.get("h");
high = highElement.getAsFloat();
final JsonElement lowElement = rateObj.get("l");
low = lowElement.getAsFloat();
final JsonElement closeElement = rateObj.get("c");
close = closeElement.getAsFloat();
}

First of all it doesn't look like a valid JSON array. It should look like this
[{"o":"1.18988","h":"1.18993","l":"1.18963","c":"1.18993"}]
Try this following code to parse it in JSON format.
JSONObject jsonObject = new JSONObject(jsonString);
JSONArray jsonArray = jsonObject.getJSONArray("mid");
for (int i = 0; i < jsonArray.length(); i++) {
jsonArray.getJSONObject(i).getString("o");
}
Then convert it your preferred data form.

parse and get specific field from HTTP response in java

I try to parse a HTTP response to a JSONObject and retrieve some fields, coould be a String or int.
My response is a json array like this:
[{nid: "24161",changed: 1445936169,created: "1444728767",language: "en",status: 1,title: "bicycle",type: "product",uid: "2172",vid: "24161"}]
And I tried using:
JSONObject myObject = new JSONObject(response);
And gson , still after parsing the response turns to {}.
Thanks for any help.

You must use JSONArray instead of JSONObject
JSONArray array = new JSONArray(response);
You can then iterate throw the array and get the fields you want
for(int i=0; i<array.length(); i++) {
JSONObject object = array.getJSONObject(i);
String nid = object.getString("nid");
int changed = object.getInt("changed");
//...
}

You are parsing json array into object. Use JSONArray instead of JSONObject
JSONArray myArray = new JSONArray(response);
you can get your object by index from your array.

How to create a dynamic JSONObject?

I have a little problem
I've write a code that create an object from JSONObject and add some data on it like this:
JSONObject outerObject = new JSONObject();
JSONArray outerArray = new JSONArray();
JSONObject innerObject1 = new JSONObject();
innerObject1.put("id", "semantic web");
innerObject1.put("url", "www.semanticweb.com");
innerObject1.put("definition", "this is the denfition of semantic web");
outerArray.put(innerObject1);
then I create another one called innerObject2 and do the same process like this:
JSONObject innerObject2 = new JSONObject();
innerObject2.put("id", "ontology");
innerObject2.put("url", "www.ontology.com");
innerObject2.put("definition", "this is the denfition of ontology");
outerArray.put(innerObject2);
outerObject.put("rows", outerArray);
return outerObject.toString();
the results will be some thing like this:
{"rows":[{"definition":"this is the denfition of semantic web","id":"semantic web","url":"www.semanticweb.com"},{"definition":"this is the denfition of ontology","id":"ontology","url":"www.ontology.com"}]}
My problem is: what if I want to create another JSONObject called innerObject3 , innerObject4 , innerObject5 .... etc using for loop?
any suggestions?

thanks for your response
I've manage to solve this problem as follow:
JSONObject outerObject = new JSONObject();
JSONArray outerArray = new JSONArray();
JSONObject [] innerObject = new JSONObject[4];
for(int i =0; i<3; i++)
{
innerObject[i]=new JSONObject();
innerObject[i].put("id", "id of "+i);
innerObject[i].put("url", "url of "+i);
innerObject[i].put("Definition", "Definition of "+i);
outerArray.put(innerObject[i]);
}
outerObject.put("rows", outerArray);
return outerObject.toString();
hope that this can help others :)

Server Response (JSON Format) to Array Conversion

I am working on an android app in which i send an http response to a server and get a response in string which is in JSON format, now on the basis of this response i need to generate a stacked column chart using AChartEngine for different equipments. The response string looks like as follows
[{"ChartDate":null,"CycleStatus":null,"Cycle_Duration":0,"Cycle_Percent":0,"Duration":0,"EquipmentDescription":"MTConnect","EquipmentId":5,"EquipmentName":"MTC 1","EquipmentStatusColor":null,"EquipmentStatusDescription":null,"EquipmentStatusId":0,"EquipmentStatusIdentifier":null,"EquipmentStatusTypeId":0,"EquipmentStatusTypeName":null,"EquipmentStatusTypeName_resourceKey":null,"EquipmentTimeZoneId":null,"EventData":null,"GeneralStatusState":0,"IsFirstRowData":false,"Percentage":0,"ReportGroupId":0,"ReportGroupName":null,"ReportGroupValue":null,"StatusAction":0,"StatusDuration":[{"ChartDate":null,"CycleStatus":null,"Cycle_Duration":0,"Cycle_Percent":0,"Duration":561.60722222222023,"EquipmentDescription":"MTConnect","EquipmentId":5,"EquipmentName":"MTC 1","EquipmentStatusColor":"#008000","EquipmentStatusDescription":"In Cycle","EquipmentStatusId":0,"EquipmentStatusIdentifier":null,"EquipmentStatusTypeId":1,"EquipmentStatusTypeName":null,"EquipmentStatusTypeName_resourceKey":"EquipmentStatusTypeName.InCycle","EquipmentTimeZoneId":null,"EventData":null,"GeneralStatusState":0,"IsFirstRowData":false,"Percentage":0,"ReportGroupId":0,"ReportGroupName":null,"ReportGroupValue":null,"StatusAction":0,"StatusDuration":null,"TimeStamp":{"DateTime":"\/Date(-62135596800000)\/","OffsetMinutes":0},"UnknownDowntime_Duration":0,"UnknownDowntime_Percent":0},{"ChartDate":null,"CycleStatus":null,"Cycle_Duration":0,"Cycle_Percent":0,"Duration":134.57583333333525,"EquipmentDescription":"MTConnect","EquipmentId":5,"EquipmentName":"MTC 1","EquipmentStatusColor":"#FFFF00","EquipmentStatusDescription":"In Cycle","EquipmentStatusId":0,"EquipmentStatusIdentifier":"","EquipmentStatusTypeId":2,"EquipmentStatusTypeName":null,"EquipmentStatusTypeName_resourceKey":"EquipmentStatusTypeName.UnknownDowntime","EquipmentTimeZoneId":null,"EventData":null,"GeneralStatusState":0,"IsFirstRowData":false,"Percentage":0,"ReportGroupId":0,"ReportGroupName":null,"ReportGroupValue":null,"StatusAction":0,"StatusDuration":null,"TimeStamp":{"DateTime":"\/Date(-62135596800000)\/","OffsetMinutes":0},"UnknownDowntime_Duration":0,"UnknownDowntime_Percent":0}],"TimeStamp":{"DateTime":"\/Date(-62135596800000)\/","OffsetMinutes":0},"UnknownDowntime_Duration":0,"UnknownDowntime_Percent":0},{"ChartDate":null,"CycleStatus":null,"Cycle_Duration":0,"Cycle_Percent":0,"Duration":0,"EquipmentDescription":null,"EquipmentId":1,"EquipmentName":"PCS Loop 1","EquipmentStatusColor":null,"EquipmentStatusDescription":null,"EquipmentStatusId":0,"EquipmentStatusIdentifier":null,"EquipmentStatusTypeId":0,"EquipmentStatusTypeName":null,"EquipmentStatusTypeName_resourceKey":null,"EquipmentTimeZoneId":null,"EventData":null,"GeneralStatusState":0,"IsFirstRowData":false,"Percentage":0,"ReportGroupId":0,"ReportGroupName":null,"ReportGroupValue":null,"StatusAction":0,"StatusDuration":[{"ChartDate":null,"CycleStatus":null,"Cycle_Duration":0,"Cycle_Percent":0,"Duration":495.61333333332925,"EquipmentDescription":null,"EquipmentId":1,"EquipmentName":"PCS Loop 1","EquipmentStatusColor":"#008000","EquipmentStatusDescription":"In Cycle","EquipmentStatusId":0,"EquipmentStatusIdentifier":null,"EquipmentStatusTypeId":1,"EquipmentStatusTypeName":null,"EquipmentStatusTypeName_resourceKey":"EquipmentStatusTypeName.InCycle","EquipmentTimeZoneId":null,"EventData":null,"GeneralStatusState":0,"IsFirstRowData":false,"Percentage":0,"ReportGroupId":0,"ReportGroupName":null,"ReportGroupValue":null,"StatusAction":0,"StatusDuration":null,"TimeStamp":{"DateTime":"\/Date(-62135596800000)\/","OffsetMinutes":0},"UnknownDowntime_Duration":0,"UnknownDowntime_Percent":0},{"ChartDate":null,"CycleStatus":null,"Cycle_Duration":0,"Cycle_Percent":0,"Duration":200.56972222222623,"EquipmentDescription":null,"EquipmentId":1,"EquipmentName":"PCS Loop 1","EquipmentStatusColor":"#FFFF00","EquipmentStatusDescription":"In Cycle","EquipmentStatusId":0,"EquipmentStatusIdentifier":"","EquipmentStatusTypeId":2,"EquipmentStatusTypeName":null,"EquipmentStatusTypeName_resourceKey":"EquipmentStatusTypeNam
Now this is a response for five different equipments and how can i use this JSON string to an array so that i can extract the data of each equipment and send it to AChartEngine for drawing of chart?

You can convert the response string to JSONObject. The response you posted is JSONArray.
JSONArray jsonArray = new JSONArray(responseString);
int size = jsonArray.length();
ArrayList<JSONObject> arrayList = new ArrayList<JSONObject>();
for(int i= 0; i< size; i++) {
JSONObject jsonObject = jsonArray.optJSONObject(i);
// use this jsonObject to get the value by passing the keys.
String value = jsonObject.optString(key);
//here is your array list of jsonobjects
arrayList.add(jsonObject);
}

Use below Code for Pass JsonArray and store Value into ArrayList.
JSONArray jArray = new JSONArray(mRes);
ArrayList<String> array1 = new ArrayList<String>();
for(int i= 0; i< size; i++) {
JSONObject jObject = jArray.getJSONObject(i);
String mValue = jObject.getString("your_json_object_name");
array1.add(mValue);
}

Use Gson api, it allows you to direct mapping of json objects to java objects. check following links for further reference:
http://code.google.com/p/google-gson/
https://sites.google.com/site/gson/gson-user-guide

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