Develop Reference

Elasticsearch improve search accuracy on Boolean query match, matchesNot, matchesPartial

Need a help about the implementation of how to improve the search accuracy of the elasticSearch logic on the JAVA side which is in the springboot application.
Why I am aiming for search accuracy? Because in the production side whenever I am searching for products using the search bar in the app ex. Laptops it shows different results of product also.
First I have a **controller class ** where the request goes to this endpoint:
#PostMapping("/bsl/view/products/sort-filter")
public Response<SearchByFilterByResponse> viewSortByFilterBy(#RequestBody SearchByDto searchBy) throws IOException{
return Response.success(elasticSearchProductBslService.viewSortByFilterBy(searchBy));
}
RequestBody contains the SearchByDto class where inside of that class I have the filterBy object, where inside of it the structure of query is there.
SearchByDto class:
SearchByDto class
FilterBy class:
private Map<String, List<String>> filter;
private List<KeyValue<String, String>> matches;
private List<KeyValue<String, String>> matchesPartial;
private List<KeyValue<String, String>> matchesNot;
private List<KeyValue<String, RangeValue>> ranges;
private List<String> discludeFieldNotNullAndEmpty;
public List<String> getDiscludeFieldNotNullAndEmpty() {
if(discludeFieldNotNullAndEmpty==null) {
this.discludeFieldNotNullAndEmpty = new ArrayList<>();
}
return discludeFieldNotNullAndEmpty;
}
public void setDiscludeFieldNotNullAndEmpty(List<String> discludeFieldNotNullAndEmpty) {
this.discludeFieldNotNullAndEmpty = discludeFieldNotNullAndEmpty;
}
public List<KeyValue<String, RangeValue>> getRanges() {
if(ranges==null) {
this.ranges = new ArrayList<>();
}
return ranges;
}
public void setRanges(List<KeyValue<String, RangeValue>> ranges) {
this.ranges = ranges;
}
public Map<String, List<String>> getFilter() {
if(filter==null) {
this.filter = new HashMap<>();
}
return filter;
}
public void setFilter(Map<String, List<String>> filter) {
this.filter = filter;
}
public List<KeyValue<String, String>> getMatches() {
if(matches==null) {
this.matches = new ArrayList<>();
}
return matches;
}
public void setMatches(List<KeyValue<String, String>> matches) {
this.matches = matches;
}
public List<KeyValue<String, String>> getMatchesPartial() {
if(matchesPartial==null) {
this.matchesPartial = new ArrayList<>();
}
return matchesPartial;
}
public void setMatchesPartial(List<KeyValue<String, String>> matchesPartial) {
this.matchesPartial = matchesPartial;
}
public List<KeyValue<String, String>> getMatchesNot() {
if(matchesNot==null) {
this.matchesNot = new ArrayList<>();
}
return matchesNot;
}
public void setMatchesNot(List<KeyValue<String, String>> matchesNot) {
this.matchesNot = matchesNot;
}
}
As based on the structure of the code the matches, matchesPartial, matchesNot is nested under the filter Map, and each keyword queries should have key and value.
Now let's go back to the controller class, as you can see inside of the Response.success method
it is calling also the elasticSearchProductBslService.viewSortByFilterBy(searchBy) where inside of the searchBy it contains the request including the filterBy.
Let's jump to the viewSortByFilterBy() method inside of the elasticSearchProductBslService class.
public SearchByFilterByResponse viewSortByFilterBy(SearchByDto searchBy) throws IOException{
SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();
SearchRequest request = new SearchRequest();
request.indices("product_bsl");
request.source(sourceBuilder);
int fromIndex = searchBy.getPagination().getFrom();
int size = searchBy.getPagination().getSize();
elasticSearchHelper.buildFieldSort(searchBy, sourceBuilder);
sourceBuilder.from(fromIndex);
sourceBuilder.size(size);
BoolQueryBuilder queryBuilder = elasticSearchHelper.boolQueryBuilder(searchBy);
sourceBuilder.query(queryBuilder);
SearchResponse response = client.search(request, RequestOptions.DEFAULT);
SearchHit[] searchHits = response.getHits().getHits();
SearchByFilterByResponse resp = new SearchByFilterByResponse();
resp.setTotalHits(response.getHits().getTotalHits().value);
List<ProductWithImage> products = searchHitToDto(searchHits);
resp.setProducts(products);
return resp;
}
Additional information for you, this is the DTO class for "product_bsl" index. As I will show it to you how it look like in the OpenAPI later.
ProductBslElasticDto class:
public class ProductBslElasticDto {
private String id;
private String name;
private List<OfferElasticDto> offers;
private List<ProductBslElasticCategory> productBslElasticCategory;
private String brandId;
private String brandName;
private String shortdesc;
private String longDesc;
private int brandRating;
private long dateInserted;
private List<String> imagePath;
private String isActive;
private List<String> images;
private List<String> imageId;
private long totalVisits;
private long totalVisitUpdateTime;
private long totalViewCount;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getBrandName() {
return brandName;
}
public void setBrandName(String brandName) {
this.brandName = brandName;
}
public String getShortdesc() {
return shortdesc;
}
public void setShortdesc(String shortdesc) {
this.shortdesc = shortdesc;
}
public String getLongDesc() {
return longDesc;
}
public void setLongDesc(String longDesc) {
this.longDesc = longDesc;
}
public int getBrandRating() {
return brandRating;
}
public void setBrandRating(int brandRating) {
this.brandRating = brandRating;
}
public String getBrandId() {
return brandId;
}
public void setBrandId(String brandId) {
this.brandId = brandId;
}
public long getDateInserted() {
return dateInserted;
}
public void setDateInserted(long dateInserted) {
this.dateInserted = dateInserted;
}
public List<ProductBslElasticCategory> getProductBslElasticCategory() {
return productBslElasticCategory;
}
public void setProductBslElasticCategory(List<ProductBslElasticCategory> productBslElasticCategory) {
this.productBslElasticCategory = productBslElasticCategory;
}
public long getTotalVisits() {
return totalVisits;
}
public void setTotalVisits(long totalVisits) {
this.totalVisits = totalVisits;
}
public long getTotalVisitUpdateTime() {
return totalVisitUpdateTime;
}
public void setTotalVisitUpdateTime(long totalVisitUpdateTime) {
this.totalVisitUpdateTime = totalVisitUpdateTime;
}
public String getIsActive() {
return isActive;
}
public void setIsActive(String isActive) {
this.isActive = isActive;
}
public List<String> getImages() {
return images;
}
public void setImages(List<String> images) {
this.images = images;
}
public List<String> getImageId() {
return imageId;
}
public void setImageId(List<String> imageId) {
this.imageId = imageId;
}
public List<OfferElasticDto> getOffers() {
return offers;
}
public void setOffers(List<OfferElasticDto> offers) {
this.offers = offers;
}
public long getTotalViewCount() {
return totalViewCount;
}
public void setTotalViewCount(long totalViewCount) {
this.totalViewCount = totalViewCount;
}
public List<String> getImagePath() {
return imagePath;
}
public void setImagePath(List<String> imagePath) {
sortIndexedImagePaths(imagePath);
this.imagePath = imagePath;
}
private void sortIndexedImagePaths(List<String> imagePaths) {
if (null == imagePaths) return;
for (String path : imagePaths) {
if (null == path ||
!PRODUCT_INDEXED_IMAGE_PATH_PATTERN.matcher(path).find()) {
return;
}
}
imagePaths.sort(String::compareTo);
}
}
Now after I show the DTO you can look back to the viewSortByFilterBy() again. I think you can disregard the SourceBuilder and SearchRequest let's focus on the elasticSearchHelper.boolQueryBuilder(searchBy) as we will jump inside of it.
ElasticSearchHelper class:
#Service
public class ElasticSearchHelper {
private static final String KEY_NAME = "name";
private static final String REGEX_SPACE = " ";
private static final String REGEX_WILDCARD = "*";
public BoolQueryBuilder boolQueryBuilder(SearchByDto searchBy) {
FilterBy filterBy = searchBy.getFilterBy();
BoolQueryBuilder rootBuilder = QueryBuilders.boolQuery();
if(filterBy!=null) {
nestedTermsQueryBuilder(rootBuilder, filterBy.getFilter());
nestedBoolQueryBuilder(rootBuilder, filterBy.getMatches(), MUST);
nestedBoolQueryBuilder(rootBuilder, filterBy.getMatchesNot(), MUST_NOT);
nestedBoolQueryBuilder(rootBuilder, filterBy.getMatchesPartial(), SHOULD);
nestedExistsQueryBuilder(rootBuilder, filterBy.getDiscludeFieldNotNullAndEmpty());
nestedRangeQueryBuilder(rootBuilder, filterBy.getRanges());
}
return rootBuilder;
}
private void nestedTermsQueryBuilder(BoolQueryBuilder rootBuilder, Map<String, List<String>> filter) {
filter.forEach((key, value) -> {
TermsQueryBuilder nestedBuilder = QueryBuilders.termsQuery(key, value);
rootBuilder.must(nestedBuilder);
});
}
private void nestedBoolQueryBuilder(BoolQueryBuilder rootBuilder, List<KeyValue<String, String>> entries, ElasticSearchBoolQueryType queryType) {
if(entries != null && !entries.isEmpty()) {
Set<String> distinctKeys = entries.stream().map(KeyValue::getKey).collect(Collectors.toSet());
for (String key : distinctKeys) {
BoolQueryBuilder nestedBuilder = QueryBuilders.boolQuery();
for (KeyValue<String, String> entry : entries) {
nestedQueryStringOrDisMaxQueryBuilder(key, entry, nestedBuilder);
}
switch (queryType) {
case MUST:
rootBuilder.must(nestedBuilder);
break;
case MUST_NOT:
rootBuilder.mustNot(nestedBuilder);
break;
case SHOULD:
rootBuilder.should(nestedBuilder);
break;
default:
break;
}
}
}
}
I just included the boolQueryBuilder and nestedBoolQueryBuilder only just to focus relating to my concern. don't get confuse on the MUST, MUST_NOT, SHOULD it is the same for matches, matchesNot, matchesPartial as I have told earlier on the FilterBy class. So in this class I think the logic happens here, any suggestions for any changes and how should I improve search accuracy for this kind of structure?
How it looks like in OpenAPI as I will search for product name:
Request: POST "/bsl/view/products/sort-filter"
{
"pagination": {
"from": 0,
"size": 20
},
"sortBy": {
"fieldsAscOrDesc": {
"offers.financing.finalAmount": "desc"
}
},
"filterBy": {
"matches": [
{
"key": "name",
"value": "Lenovo IdeaPad3 81Y4001NPH"
}
],
"matchesNot": [
{
"key": "isActive",
"value": "false"
}
],
"discludeFieldNotNullAndEmpty": [
"offers"
]
}
}
Result was it had total of 17 hits and I used the matches keyword where it should be search the exact word right? But it shows different Lenovo products in the result.
Result

Using Jackson to produce desired JSON response

Could anyone tell me what am I doing wrong while printing the JSON using Jackson. Here's my controller code :
#RequestMapping(value="/get_employee_details", method=RequestMethod.GET)
public String updateemployee
(
#RequestParam(value="emp_id", defaultValue="0") Integer emp_id,
#RequestParam(value="name", defaultValue="") String name
)
{
String responseJSON = null;
boolean getStatus = true;
try {
EmployeeDao employeeDao = (EmployeeDao)context.getBean("employeeDao");
Employee employee = null;
List<Employee> empList = employeeDao.findByEmployeeId(emp_id);
if ((empList != null) && (!empList.isEmpty())) {
List<String> empStatus = new ArrayList<String>();
for(Employee emp : empList){
empStatus.add(emp.addJoinString());
responseJSON = GenericOrmStatusView.OrmResponseToJsonString(true, 1,empStatus, true);
}
}
}
return responseJSON;
}
I have the following method defined in my Employee class :
public String addJoinString() {
return String.format("ID: %d",Name: %s," ,this.EmployeeId,this.name);
}
Since I am running a for loop in the code here and sending the list empStatus to the OrmResponseToJsonString method :
for(Employee emp : empList){
empStatus.add(emp.addJoinString());
responseJSON = GenericOrmStatusView.OrmResponseToJsonString(true, 1,empStatus, true);
I am getting the following JSON response :
{
"status" : "SUCCESS",
"employeeStatus" : [ "ID: 81, Name: Jack", "ID: 83, Name: Anthony", "ID: 88, Name: Stephanie", "ID: 25, Name: Kelly", "ID: 02, Name: Jessica" ]
}
However, I would like to be it in the following format:
{
"status" : "SUCCESS",
"message": " "
},
"employeeStatus":[{
"ID":81,
"Name":"Jack"
},
{
"ID":88,
"Name":"Anthony"
},
and so on and so forth ....
]
For Reference:
My OrmResponseToJsonString method is defined as follows inside GenericOrmStatusView class
public class GenericOrmStatusView extends Views
{
public static String OrmResponseToJsonString(boolean success, List<String> eStatus,boolean pretty)
{
PrintemployeeStatusIDAndStatus statusMsg = WebServiceUtils.printNameAndID(success, eStatus);
String genericOrmStatusJsonString = null;
try {
ObjectMapper objectMapper = new ObjectMapper();
objectMapper.configure(SerializationFeature.INDENT_OUTPUT, pretty);
genericOrmStatusJsonString = objectMapper.writerWithView(Views.Normal.class).writeValueAsString(statusMsg);
//genericOrmStatusJsonString = objectMapper.writerWithView(Views.Normal.class).writeValueAsString(eStatus);
} catch(Exception e) {
e.printStackTrace();
}
return genericOrmStatusJsonString;
}
}
And my printNameAndID method is defined as follows inside WebServiceUtils class :
public class WebServiceUtils
{
public static PrintNameAndID printNameAndID(boolean success, List<String> eStatus)
{
PrintNameAndID statusMsgAndRegID = new PrintNameAndID();
if (success) {
statusMsgAndRegID.setStatus("SUCCESS");
statusMsgAndRegID.setemployeeStatus(eStatus);
} else {
statusMsgAndRegID.setStatus("ERROR");
//statusMsgAndRegID.setemployeeStatus("");
}
return statusMsgAndRegID;
}
}

The easiest way to get desired JSON output, is to create an object model representing the data, e.g.
public class MyJSON {
private MyStatus status;
private List<EmployeeStatus> employeeStatus = new ArrayList<>();
public MyJSON(String status, String message) {
this.status = new MyStatus(status, message);
}
public void addEmployeeStatus(int id, String name) {
this.employeeStatus.add(new EmployeeStatus(id, name));
}
public MyStatus getStatus() {
return this.status;
}
public List<EmployeeStatus> getEmployeeStatus() {
return this.employeeStatus;
}
}
public class MyStatus {
private String status;
private String message;
public MyStatus(String status, String message) {
this.status = status;
this.message = message;
}
public String getStatus() {
return this.status;
}
public String getMessage() {
return this.message;
}
}
public class EmployeeStatus {
private int id;
private String name;
public EmployeeStatus(int id, String name) {
this.id = id;
this.name = name;
}
#JsonProperty("ID")
public int getId() {
return this.id;
}
#JsonProperty("Name")
public String getName() {
return this.name;
}
}
You can then create JSON text like this:
MyJSON myJSON = new MyJSON("SUCCESS", " ");
myJSON.addEmployeeStatus(81, "Jack");
myJSON.addEmployeeStatus(88, "Anthony");
ObjectMapper objectMapper = new ObjectMapper();
objectMapper.configure(SerializationFeature.INDENT_OUTPUT, true);
String json = objectMapper.writeValueAsString(myJSON);
System.out.println(json);
Output
{
"status" : {
"status" : "SUCCESS",
"message" : " "
},
"employeeStatus" : [ {
"ID" : 81,
"Name" : "Jack"
}, {
"ID" : 88,
"Name" : "Anthony"
} ]
}
As mentioned by chrylis in a comment:
As a note, you can normally let Spring do this automatically and just return empList from your controller method.
Which for the above code would mean something like this:
#GetMapping(path="/foo", produces="application/json")
public MyJSON foo() {
MyJSON myJSON = new MyJSON("SUCCESS", " ");
myJSON.addEmployeeStatus(81, "Jack");
myJSON.addEmployeeStatus(88, "Anthony");
return myJSON;
}

Deserializing JSON array of objects using GSON

This is one in a row of deserialization questions but I've read them all and can't figure out the solution for my problem.
I need to get all the "entery"->"content" ->$t and "entery"->"title"->"$t" but in CategoryDeserializer() I get JsonArray that is NULL. I've pointed to that part of the code with "<====".
Error message:
Attempt to invoke interface method 'java.util.Iterator
java.util.List.iterator()' on a null object reference
I have JSON that looks something like this:
{ "feed":{
"id":{ ... },
"author":[ ... ],
"entry":[
{
"id":{ },
"updated":{ },
"category":[ ],
"title":{
"type":"text",
"$t":"A1 },
"content":{
"type":"text",
"$t":"test"
},
"link":[ ]
},
{ ... },
{ ... },
{ ...},
]
}
}
This is part of my code where I try to deserialize "entery":
String json = response.body().toString();
Type listType = new TypeToken<List<Entry>>() {
}.getType();
Gson gson = new GsonBuilder().registerTypeAdapter(listType, new CategoryDeserializer()).create();
List<Entry> list = gson.fromJson(json, listType);
for (Entry entry : list) {
Log.i("MainActivity", "Content: " + entry.getContent());}
Where CategoryDeserializer() looks like this:
public class CategoryDeserializer implements JsonDeserializer<List<Entry>> {
public List<Entry> deserialize(JsonElement je, Type type, JsonDeserializationContext jdc) throws JsonParseException {
JsonArray entry = je.getAsJsonObject().getAsJsonArray("entry"); //<==== here I get that entry is null but je has a value
ArrayList<Entry> myList = new ArrayList<Entry>();
for (JsonElement e : entry) {
myList.add((Entry) jdc.deserialize(e, Entry.class));
}
return myList;}
And my Entry class:
public class Entry {
private Id_ id;
private Updated_ updated;
private List<Category_> category = null;
private Title_ title;
private Content content;
private List<Link_> link = null;
//getters and setters
public Id_ getId() {
return id;
}
public void setId(Id_ id) {
this.id = id;
}
public Updated_ getUpdated() {
return updated;
}
public void setUpdated(Updated_ updated) {
this.updated = updated;
}
public List<Category_> getCategory() {
return category;
}
public void setCategory(List<Category_> category) {
this.category = category;
}
public Title_ getTitle() {
return title;
}
public void setTitle(Title_ title) {
this.title = title;
}
public Content getContent() {
return content;
}
public void setContent(Content content) {
this.content = content;
}
public List<Link_> getLink() {
return link;
}
public void setLink(List<Link_> link) {
this.link = link;
}
}
Edit: I have declaration and instantiation.

I was complicating things that were not complicated. All I had to do was this:
String json = response.body().toString();
Gson mGson = new Gson();
//where Example is the root of JSON
Example rsp = mGson.fromJson(json, Example.class);
//Entry is the list I needed to access
List <Entry> listOfEntrys= rsp.getFeed().getEntry();
//get value
Log.i("MainActivity", "listaEntrya " + listOfEntrys.get(0).getTitle().get$t());

Converting JSONArray to List<Object>?

I'm trying deserializes a JSONArray to List. To do it I'm trying use Gson but I can't understand why doesn't works and all values of JSON are null.
How could I do this ?
JSON
{ "result" : [
{ "Noticia" : {
"created" : "2015-08-20 19:58:49",
"descricao" : "tttttt",
"id" : "19",
"image" : null,
"titulo" : "ddddd",
"usuario" : "FERNANDO PAIVA"
} },
{ "Noticia" : {
"created" : "2015-08-20 19:59:57",
"descricao" : "hhhhhhhh",
"id" : "20",
"image" : "logo.png",
"titulo" : "TITULO DA NOTICIA",
"usuario" : "FERNANDO PAIVA"
} }
] }
Deserializes
List<Noticia> lista = new ArrayList<Noticia>();
Gson gson = new Gson();
JSONArray array = obj.getJSONArray("result");
Type listType = new TypeToken<List<Noticia>>() {}.getType();
lista = gson.fromJson(array.toString(), listType);
//testing - size = 2 but value Titulo is null
Log.i("LISTSIZE->", lista.size() +"");
for(Noticia n:lista){
Log.i("TITULO", n.getTitulo());
}
Class Noticia
public class Noticia implements Serializable {
private static final long serialVersionUID = 1L;
private Integer id;
private String titulo;
private String descricao;
private String usuario;
private Date created;
private String image;

There are two problems with your code :
First is that you are using a getJsonArray() to get the array,
which isn't part of Gson library, you need to use
getAsJsonArray() method instead.
Second is that you are using array.toString() which isn't obvious
because for the fromJson method you need a jsonArray as
parameter and not String and that will cause you parse problems, just remove it.
And use the following code to convert your jsonArray to List<Noticia> :
Type type = new TypeToken<List<Noticia>>() {}.getType();
List<Noticia> lista = gson.fromJson(array, type);
And your whole code will be:
Gson gson = new Gson();
JSONArray array = obj.getAsJsonArray("result");
Type type = new TypeToken<List<Noticia>>() {}.getType();
List<Noticia> lista = gson.fromJson(array, type);
//testing - size = 2 but value Titulo is null
Log.i("LISTSIZE->", lista.size() +"");
for(Noticia n:lista){
Log.i("TITULO", n.getTitulo());
}

I think the problem could be something to do with toString() on JSONArray. But are you using obj.getAsJsonArray method?
Try this:
JSONArray arr = obj.getAsJsonArray("result");
Type listType = new TypeToken<List<Noticia>>() {
}.getType();
return new Gson().fromJson(arr , listType);

Noticia.java
public class Noticia {
private String created;
private String descricao;
private String id;
private String image;
private String titulo;
private String usuario;
public String getCreated() {
return created;
}
public void setCreated(String created) {
this.created = created;
}
public String getDescricao() {
return descricao;
}
public void setDescricao(String descricao) {
this.descricao = descricao;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getImage() {
return image;
}
public void setImage(String image) {
this.image = image;
}
public String getTitulo() {
return titulo;
}
public void setTitulo(String titulo) {
this.titulo = titulo;
}
public String getUsuario() {
return usuario;
}
public void setUsuario(String usuario) {
this.usuario = usuario;
}
#Override
public String toString() {
return "Noticia [created=" + created + ", descricao=" + descricao
+ ", id=" + id + ", image=" + image + ", titulo=" + titulo
+ ", usuario=" + usuario + "]";
}
}
Result.java
public class Result {
private Noticia Noticia;
public Noticia getNoticia() {
return Noticia;
}
public void setNoticia(Noticia noticia) {
Noticia = noticia;
}
#Override
public String toString() {
return "Result [Noticia=" + Noticia + "]";
}
}
Item.java
import java.util.List;
public class Item {
private List<Result> result;
public List<Result> getResult() {
return result;
}
public void setResult(List<Result> result) {
this.result = result;
}
#Override
public String toString() {
return "Item [result=" + result + "]";
}
}
Main.java
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.testgson.beans.Item;
public class Main {
private static Gson gson;
static {
gson = new GsonBuilder().create();
}
public static void main(String[] args) {
String j = "{\"result\":[{\"Noticia\":{\"created\":\"2015-08-20 19:58:49\",\"descricao\":\"tttttt\",\"id\":\"19\",\"image\":null,\"titulo\":\"ddddd\",\"usuario\":\"FERNANDO PAIVA\"}},{\"Noticia\":{\"created\":\"2015-08-20 19:59:57\",\"descricao\":\"hhhhhhhh\",\"id\":\"20\",\"image\":\"logo.png\",\"titulo\":\"TITULO DA NOTICIA\",\"usuario\":\"FERNANDO PAIVA\"}}]}";
Item r = gson.fromJson(j, Item.class);
System.out.println(r);
}
}
Final result
Item [result=[Result [Noticia=Noticia [created=2015-08-20 19:58:49, descricao=tttttt, id=19, image=null, titulo=ddddd, usuario=FERNANDO PAIVA]], Result [Noticia=Noticia [created=2015-08-20 19:59:57, descricao=hhhhhhhh, id=20, image=logo.png, titulo=TITULO DA NOTICIA, usuario=FERNANDO PAIVA]]]]

You parse json, that looks like
{ "result" : [
{
"created" : "2015-08-20 19:58:49",
"descricao" : "tttttt",
"id" : "19",
"image" : null,
"titulo" : "ddddd",
"usuario" : "FERNANDO PAIVA"
},
{
"created" : "2015-08-20 19:59:57",
"descricao" : "hhhhhhhh",
"id" : "20",
"image" : "logo.png",
"titulo" : "TITULO DA NOTICIA",
"usuario" : "FERNANDO PAIVA"
}
] }
You need to make another object Item and parse a list of them.
public class Item{
Noticia noticia;
}
Or you can interate through JSONArray, get field "noticia" from each then parse Noticia object from given JSONObject.

Kotlin Ex :
we getting response in form of JSONArry
call.enqueue(object : Callback<JsonArray> {
override fun onResponse(call: Call<JsonArray>, response: Response<JsonArray>) {
val list = response.body().toString()
val gson = Gson()
val obj: CitiesList? = gson.fromJson(list, CitiesList::class.java)
cityLiveData.value = obj!!
}
override fun onFailure(call: Call<JsonArray>, t: Throwable) {
}
})
Here CitiesList CitiesList::class.java is the ArrayList of Cities object
class CitiesList : ArrayList<CitiesListItem>()
Before using GSON add dependancey in Gradle
dependencies {
implementation 'com.google.code.gson:gson:2.8.8'
}

How to create a json tree with one root node with couple of child nodes

I have created a json which have a root node with couple of child nodes using java now i have a requirement that the child node under the root may also have some children.But i am unable to do that.Here is what i have done so far....
class Entry {
private String name;
public String getChildren() {
return name;
}
public void setChildren(String name) {
this.name = name;
}
}
public class JsonApplication {
public static void main(String[] args) {
// TODO code application logic here
String arr[] = {"Culture", "Salary", "Work", "Effort"};
EntryListContainer entryListContainer = new EntryListContainer();
List<Entry> entryList1 = new ArrayList<>();
List<Entry> entryList2 = new ArrayList<>();
for (int i = 0; i < arr.length; i++) {
Entry entry1 = new Entry();
entry1.setChildren(arr[i]);
entryList1.add(entry1);
entryList2.add(entry1);
/*Child nodes are created here and put into entryListContainer*/
entryListContainer.setEntryList1(entryList1);
entryListContainer.setEntryList1(entryList2);
}
/*Root node this will collapse and get back to Original position on click*/
entryListContainer.setName("Employee");
entryListContainer.setName("Culture");
Map<String, String> mapping = new HashMap<>();
mapping.put("entryList1", "name");
Gson gson = new GsonBuilder().serializeNulls().setFieldNamingStrategy(new DynamicFieldNamingStrategy(mapping)).create();
System.out.println(gson.toJson(entryListContainer));
}
}
class DynamicFieldNamingStrategy implements FieldNamingStrategy {
private Map<String, String> mapping;
public DynamicFieldNamingStrategy(Map<String, String> mapping) {
this.mapping = mapping;
}
#Override
public String translateName(Field field) {
String newName = mapping.get(field.getName());
if (newName != null) {
return newName;
}
return field.getName();
}
}
class EntryListContainer {
private List<Entry> children;
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public void setEntryList1(List<Entry> entryList1) {
this.children = entryList1;
}
public List<Entry> getEntryList1() {
return children;
}
}
This is the json output i am getting
{
"children": [
{
"name":"Culture"
},
{
"name":"Salary"
},
{
"name":"Work"
},
{
"name":"Effort"
}
],
"name":"Employee"
}
But i need
{
"name":"Culture",
"children":[
{
"name":"Culture"
},
{
"name":"Salary"
},
{
"name":"Work"
},
{
"name":"Effort"
}
],
"name":"Work",
"children" : [
{
"name":"Culture"
},
{
"name":"Work"
}
]
}

I'm a bit confused by your code, but something is clear to me: what you want to get. So starting from scratch I created some code you can copy&run to see how you can get your desired JSON.
Probably the order of elements is important for you (pay attention that in JSON object order of keys is not important -is a map!-), so I edited some code that is not pure Gson way of doing things but that creates exactly your example.
package stackoverflow.questions;
import java.lang.reflect.Field;
import java.util.*;
import com.google.gson.*;
public class JsonApplication {
public static class EntryListContainer {
public List<Entry> children = new ArrayList<Entry>();
public Entry name;
}
public static class Entry {
private String name;
public Entry(String name) {
this.name = name;
}
}
public static void main(String[] args) {
EntryListContainer elc1 = new EntryListContainer();
elc1.name = new Entry("Culture");
elc1.children.add(new Entry("Salary"));
elc1.children.add(new Entry("Work"));
elc1.children.add(new Entry("Effort"));
EntryListContainer elc2 = new EntryListContainer();
elc2.name = new Entry("Work");
elc2.children.add(new Entry("Culture"));
elc2.children.add(new Entry("Work"));
ArrayList<EntryListContainer> al = new ArrayList<EntryListContainer>();
Gson g = new Gson();
al.add(elc1);
al.add(elc2);
StringBuilder sb = new StringBuilder("{");
for (EntryListContainer elc : al) {
sb.append(g.toJson(elc.name).replace("{", "").replace("}", ""));
sb.append(",");
sb.append(g.toJson(elc.children));
sb.append(",");
}
String partialJson = sb.toString();
if (al.size() > 1) {
int c = partialJson.lastIndexOf(",");
partialJson = partialJson.substring(0, c);
}
String finalJson = partialJson + "}";
System.out.println(finalJson);
}
}
and this is the execution:
{"name":"Culture",[{"name":"Salary"},{"name":"Work"},{"name":"Effort"}],"name":"Work",[{"name":"Culture"},{"name":"Work"}]}