stucked at accessing nested json. similar stuff:
[
{
key-value,
key-value
},
{
key-value,
key-value
},
{
key-value,
key-value
}
]
works nicely but when i try:
{
"alfa":{
"id":"foo",
"product":{
"id":"foo1",
"price":"foo2"
}
},
"beta":{
"id":"foo",
"product":{
"id":"foo1",
"price":"foo2"
}
}
}
i get error:
com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize value of type `java.util.ArrayList<...
i of course did change structure of classes:
public class Alphabet{
private Purchase purchase;
...
public class Purchase{
private String id;
private Product product;
...
public class Product {
private String id;
private String price;
...
to read it:
ObjectMapper mapper = new ObjectMapper();
InputStream inputStream = new FileInputStream(new File("src/main/json/file.json"));
TypeReference<List<Alphabet>> typeReference = new TypeReference<List<Alphabet>>() {};
List<Alphabet> alphabet= mapper.readValue(inputStream, typeReference);
System.out.println(alphabet);
whats wrong, please?
It seems like the JSON structure you try to read is not a List<Alphabet>, but a Map<String, Purchase>.
Your second json not like list of object. The second json look lik have 2 main objects if so you need class like below.
public class Alphabet{
private Purchase purchase;
private Purchase purchase1;
}
But it not good practice. Use as first josn like list of objects.
I'm consuming an external API, for which a JSON Object is returned. Contained in that Object response is an array that I need to extract and set to a List of a particular entity type. Java, however, is not a language that I'm very familiar with, so I'm having problems attempting to figure this out.
I've created a type of wrapper class to work with this in the setter.
The best I've come up with that compiles is below, but produces an error that I can't figure out.
public void setFlights(Object responseBody) {
String responseString = responseBody.toString();
JSONObject responseJSONObject = new JSONObject(responseString);
JSONArray responseJSONArray = responseJSONObject.getJSONArray("flights");
Gson gson = new Gson();
Type flightType = new TypeToken<List<Flight>>() {}.getType();
this.flights = gson.fromJson(String.valueOf(responseJSONArray), flightType);
}
As you can see, I'm kind of throwing it at the wall to see if it will stick. I'm trying to use Gson to get around some of the Type issues I've come across.
The error produced when executing is:
org.json.JSONException: Expected a ':' after a key at 7 [character 8 line 1]
Response String is as follows:
Response String Image
If that's difficult to deal with, here's the response in text:
INFO: {"FlightInfoResult":{"next_offset":-1,"flights":[{"ident":"N1RJ","aircrafttype":"HDJT","filed_ete":"01:25:00","filed_time":1593038253,"filed_departuretime":1593037500,"filed_airspeed_kts":400,"filed_airspeed_mach":"","filed_altitude":360,"route":"WEAZL4 CLAWD","actualdeparturetime":1593038285,"estimatedarrivaltime":1593043320,"actualarrivaltime":1593043320,"diverted":"","origin":"KJQF","destination":"KJXN","originName":"Concord-Padgett Rgnl","originCity":"Concord, NC","destinationName":"Jackson County","destinationCity":"Jackson, MI"},{"ident":"N1RJ","aircrafttype":"HDJT","filed_ete":"01:24:00","filed_time":1593000320,"filed_departuretime":1592998200,"filed_airspeed_kts":400,"filed_airspeed_mach":"","filed_altitude":350,"route":"PEGTE","actualdeparturetime":1593000420,"estimatedarrivaltime":1593005149,"actualarrivaltime":1593005149,"diverted":"","origin":"KJXN","destination":"KJQF","originName":"Jackson County","originCity":"Jackson, MI","destinationName":"Concord-Padgett Rgnl","destinationCity":"Concord, NC"},{"ident":"N1RJ","aircrafttype":"HDJT","filed_ete":"01:29:00","filed_time":1592518049,"filed_departuretime":1592513400,"filed_airspeed_kts":317,"filed_airspeed_mach":"","filed_altitude":360,"route":"WEAZL4 CLAWD","actualdeparturetime":1592517936,"estimatedarrivaltime":1592523120,"actualarrivaltime":1592523120,"diverted":"","origin":"KJQF","destination":"KJXN","originName":"Concord-Padgett Rgnl","originCity":"Concord, NC","destinationName":"Jackson County","destinationCity":"Jackson, MI"},{"ident":"N1RJ","aircrafttype":"HDJT","filed_ete":"01:24:00","filed_time":1592481020,"filed_departuretime":1592479800,"filed_airspeed_kts":319,"filed_airspeed_mach":"","filed_altitude":350,"route":"PEGTE","actualdeparturetime":1592481126,"estimatedarrivaltime":1592486100,"actualarrivaltime":1592486100,"diverted":"","origin":"KJXN","destination":"KJQF","originName":"Jackson County","originCity":"Jackson, MI","destinationName":"Concord-Padgett Rgnl","destinationCity":"Concord, NC"}]}}
There very well may be a much more simple way of accomplishing what I need. Any example help is very much appreciated.
You can use Gson string to object mapper class directly as like below,
package com.sample.programs;
import java.util.List;
import com.google.gson.Gson;
public class FlightInfoResultMain {
public static void main(String[] args) {
String input = "{\"FlightInfoResult\":{\"next_offset\":-1,\"flights\":[{\"ident\":\"N1RJ\",\"aircrafttype\":\"HDJT\",\"filed_ete\":\"01:25:00\",\"filed_time\":1593038253,\"filed_departuretime\":1593037500,\"filed_airspeed_kts\":400,\"filed_airspeed_mach\":\"\",\"filed_altitude\":360,\"route\":\"WEAZL4 CLAWD\",\"actualdeparturetime\":1593038285,\"estimatedarrivaltime\":1593043320,\"actualarrivaltime\":1593043320,\"diverted\":\"\",\"origin\":\"KJQF\",\"destination\":\"KJXN\",\"originName\":\"Concord-Padgett Rgnl\",\"originCity\":\"Concord, NC\",\"destinationName\":\"Jackson County\",\"destinationCity\":\"Jackson, MI\"},{\"ident\":\"N1RJ\",\"aircrafttype\":\"HDJT\",\"filed_ete\":\"01:24:00\",\"filed_time\":1593000320,\"filed_departuretime\":1592998200,\"filed_airspeed_kts\":400,\"filed_airspeed_mach\":\"\",\"filed_altitude\":350,\"route\":\"PEGTE\",\"actualdeparturetime\":1593000420,\"estimatedarrivaltime\":1593005149,\"actualarrivaltime\":1593005149,\"diverted\":\"\",\"origin\":\"KJXN\",\"destination\":\"KJQF\",\"originName\":\"Jackson County\",\"originCity\":\"Jackson, MI\",\"destinationName\":\"Concord-Padgett Rgnl\",\"destinationCity\":\"Concord, NC\"},{\"ident\":\"N1RJ\",\"aircrafttype\":\"HDJT\",\"filed_ete\":\"01:29:00\",\"filed_time\":1592518049,\"filed_departuretime\":1592513400,\"filed_airspeed_kts\":317,\"filed_airspeed_mach\":\"\",\"filed_altitude\":360,\"route\":\"WEAZL4 CLAWD\",\"actualdeparturetime\":1592517936,\"estimatedarrivaltime\":1592523120,\"actualarrivaltime\":1592523120,\"diverted\":\"\",\"origin\":\"KJQF\",\"destination\":\"KJXN\",\"originName\":\"Concord-Padgett Rgnl\",\"originCity\":\"Concord, NC\",\"destinationName\":\"Jackson County\",\"destinationCity\":\"Jackson, MI\"},{\"ident\":\"N1RJ\",\"aircrafttype\":\"HDJT\",\"filed_ete\":\"01:24:00\",\"filed_time\":1592481020,\"filed_departuretime\":1592479800,\"filed_airspeed_kts\":319,\"filed_airspeed_mach\":\"\",\"filed_altitude\":350,\"route\":\"PEGTE\",\"actualdeparturetime\":1592481126,\"estimatedarrivaltime\":1592486100,\"actualarrivaltime\":1592486100,\"diverted\":\"\",\"origin\":\"KJXN\",\"destination\":\"KJQF\",\"originName\":\"Jackson County\",\"originCity\":\"Jackson, MI\",\"destinationName\":\"Concord-Padgett Rgnl\",\"destinationCity\":\"Concord, NC\"}]}}";
System.out.println("input - " + input);
//Create Gson object
Gson gson = new Gson();
FlightInfoResultObject responseObject = gson.fromJson(input, FlightInfoResultObject.class);
// parsing response to java pojo
List<Flights> listOfFlights = responseObject.getFlightInfoResult().getFlights();
for (Flights flight : listOfFlights) {
System.out.println("flight - " + flight.getIdent());
}
}
}
Object Mapping class: Inside Flights.class you can add all the variable which you have in json response.
class FlightInfoResultObject {
FlightInfoResult FlightInfoResult;
#Getter
#Setter
}
class FlightInfoResult {
Integer next_offset;
List<Flights> flights;
#Getter
#Setter
}
class Flights {
String ident;
String aircrafttype;
#Getter
#Setter
}
I think it's impossible to retrieve the inner JSON element directly using gson.
You have to get FlightInfoResult then flights accordingly. This should work:
Gson gson = new Gson();
JsonObject jsonObject = com.google.gson.JsonParser.parseString(responseString).getAsJsonObject();
JsonArray flightArray = jsonObject.getAsJsonObject("FlightInfoResult").getAsJsonArray("flights");
Type flightType = new TypeToken<List<Flight>>() {}.getType();
List<Flight> flights = gson.fromJson(flightArray, flightType);
Anyway, make sure the name of all properties inside class Flight matches Json elements name, to avoid mapping errors.
Since you didn't post your Flight class definition and gson naming rule, but the Flight class should be like:
public class Flight {
private String ident;
private String aircrafttype;
private String filed_ete;
private float filed_time;
private float filed_departuretime;
private float filed_airspeed_kts;
private String filed_airspeed_mach;
private float filed_altitude;
private String route;
private float actualdeparturetime;
private float estimatedarrivaltime;
private float actualarrivaltime;
private String diverted;
private String origin;
private String destination;
private String originName;
private String originCity;
private String destinationName;
private String destinationCity;
// getters setters
I'm having problem to assign json data into java class.Please do help anyone,
My java class is like,
public class ListofGridRecords<T> {
public int Totalrecords;
public List<T> GridRecords;//using TraderTransaction class.
}
and TraderTransaction class is,
public class TraderTransaction {
public Date AddedTime;
public String TransactId;
public TransactStatus Status;
public String OtherPartyAccountNo;
public Double AmountPaid;
public Double AmountRecieved;
public Double ClosingBalance;
public TransactionTypes TransType;
public String Narration;
public TraderTransaction() {
super();
}
}
and my json conversion function look like,
JsonObject returndata = JsonObject.parse(responseString);
String operationresult = returndata.get("OperationResult").toString();
if (Result.values()[Integer.parseInt(operationresult)] == Result.Success) {
Gson gson = new Gson();
#SuppressWarnings("unchecked")
ListofGridRecords<TraderTransaction> traderlist =
gson.fromJson(returndata.get("ResultData").toString(), ListofGridRecords.class);
Log.i("LIST DATA:", "" + traderlist);
for (TraderTransaction trader: traderlist.GridRecords) {
HashMap<String, String> map = new HashMap<String, String>();
map.put(TRANS_FIRST_COLUMN, currentformatter.format(trader.AddedTime));
map.put(TRANS_SECOND_COLUMN, trader.TransactId);
map.put(TRANS_THIRD_COLUMN, trader.OtherPartyAccountNo);
map.put(TRANS_FOURTH_COLUMN, trader.AmountPaid.toString());
map.put(TRANS_FIFTH_COLUMN, trader.AmountRecieved.toString());
map.put(TRANS_SIXTH_COLUMN, OpenOrClosed.values()[Integer.parseInt(trader.TransType.toString())].toString());
list.add(map);
}
}
I'm getting conversion error at for (TraderTransaction trader : traderlist.GridRecords).
My Json data look like,
{
"Messages":"RESULTS_RETRIEVAL_SUCCESSFULL",
"OperationResult":0,
"ResultData":{
"GridRecords":[
{
"AddedBy":"Distributor-9787457361-Rathinavel",
"AddedTime":"2013-04-12T16:26:24.0140117",
"AmountPaid":0.0,
"AmountRecieved":10000.0,
"ClosingBalance":10000.0,
"Narration":null,
"OtherPartyAccountNo":"0102849015327675",
"Status":2,
"TransType":2,
"TransactId":"TDRF483679051236"
},
{
"AddedBy":"Distributor-9787457361-Rathinavel",
"AddedTime":"2013-04-12T16:20:54.8681857",
"AmountPaid":0.0,
"AmountRecieved":0.0,
"ClosingBalance":0.0,
"Narration":null,
"OtherPartyAccountNo":"0102849015327675",
"Status":0,
"TransType":2,
"TransactId":"TDRF706925413802"
}
],
"Totalrecords":2
},
"UpdateAvailable":"0"
}
In order to parse your JSON, I'd use a slightly different strategy. As you seem to be interested in parsing only the "ResultData", I'd create classes to wrap the response, very similar to those you have already created, namely:
public class Response {
#SerializedName("ResultData")
public ResultData resultData;
}
and,
public class ResultData {
#SerializedName("GridRecords")
public List<GridRecord> gridRecords;
#SerializedName("Totalrecords")
public int totalrecords;
}
and,
public class GridRecord {
#SerializedName("AddedTime")
public String addedTime;
#SerializedName("TransactId")
public String transactId;
//other fields...
}
and other classes if necessary...
Then, in order to parse your JSON reponse, you just have to do:
Gson gson = new Gson();
Response data = gson.fromJson(responseString, Response.class);
and you'll be able to access any field, for example:
data.resultData.gridRecords.transactId;
Note 1: If you are interested in more fields of the JSON response, you just have to add more fields to your wrap classes, according to the JSON response...
Note 2: I've changed the type of addedTime to String, instead of Date because it throws an exception for unparseable date. Anyway I usually leave the types in the Response objects as simple String and then in the class from where I retrieve the response, I do the correct formatting while creating my objects, for example, when you put the values in your Map...
Note 3: The use of the annotation #SerializedName is interesting to separate the name of a field in the JSON response and in your app, in order to follow Java naming conventions, which your attributes are not following...
Note 4: You shouldn't use public attributes in your classes. It's more recommendable to use private/protected attributes and their correspondent getters and setters...
I'm having trouble parsing the following JSON with Google's Gson:
{"Name":
{"object1":
{"field1":"17",
"field2":"360",
"field3":"19",
"field4":"sun",
"field5":"rain"
}
}
}
I have tried the following to get the value of field1 but it doesn't work
#SerializedName("Name/object1/field1")
public int fieldOne;
What am I doing wrong?
Your objects have to conserve the hierarchy of your json instructions. For your example, it would be something like this:
public class Object {
#SerializedName("field1")
public String fieldOne;
#SerializedName("field2")
public String fieldTwo;
#SerializedName("field3")
public String fieldThree;
#SerializedName("field4")
public String fieldFour;
}
public class Name {
#SerializedName("object1")
public Object obj;
}
public class GsonObj {
#SerializedName("Name")
public Name name;
}
Using the following call:
String json = "{\"Name\":{" +
"\"object1\":{" +
"\"field1\":\"17\",\"field2\":\"360\",\"field3\":\"19\",\"field4\":\"sun\",\"field5\":\"rain\"}}}";
Gson gson = new Gson();
GsonObj jsonResult = gson.fromJson(json, GsonObj.class);
Log.d("test", "field one: "+jsonResult.name.obj.fieldOne);
Log.d("test", "field two: "+jsonResult.name.obj.fieldTwo);
Log.d("test", "field three: "+jsonResult.name.obj.fieldThree);
Log.d("test", "field four: "+jsonResult.name.obj.fieldFour);
You have invalid JSON. JSON may either start with { or [ so you need to wrap your string with another pair of {}.
A good practice is to always check your data first. I often use this here:
http://jsonlint.com/
I don't think you can have "Name/object1/field" you have to specify key name directly without hierarchy.
refer How to parse dynamic JSON fields with GSON?