We Keep Coding

Deserialize Json to java object

I am using Lombok to create builder pattern for my java object and I want to convert json into this object but it keeps saying cannot deserialize object.
#Builder
#Getter
#Setter
#Value
#NoArgConstructor
#JsonDeserialize()
#JsonInclude(JsonInclude.Include.NON_NULL)
#JsonIgnoreProperties(ignoreUnknown = true)
public class SaleInfo {
private String country;
private String saleability; //This
private boolean isEbook; //THis
// created only if required
private String buyLink;
//TODO i want to have a conditional creation of this two objects below.
ListPrice listPrice;
RetailPrice retailPrice;
#Override
public boolean equals(Object o) {
return EqualsBuilder.reflectionEquals(this, o);
}
#Override
public int hashCode() {
return HashCodeBuilder.reflectionHashCode(this);
}
#Override
public String toString() {
return ReflectionToStringBuilder.toString(this);
}
This is my code for using object mapper
public NodeBean readFromJsonFile() throws IOException {
objectMapper.configure(
DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
InputStream resourceAsStream = getClass().getClassLoader().getResourceAsStream("book.json");
JsonNode node = objectMapper.readTree(resourceAsStream);
NodeBean nodebean = objectMapper.readerFor(NodeBean.class).readValue(node);
return nodebean;
}
It works fine when I implemented getters and setters and remove all lombok annotations, but I need it as a builder pattern, it's important (due to some optional objects like Listprice).
I am getting the error when i try to deserialize
com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of `com.valentine.cognifide_task.model.SaleInfo` (no Creators, like default construct, exist): cannot deserialize from Object value (no delegate- or property-based Creator)
at [Source: UNKNOWN; line: -1, column: -1] (through reference chain: com.valentine.cognifide_task.model.NodeBean["items"]->java.util.ArrayList[0]->com.valentine.cognifide_task.model.Item["saleInfo"])
This is the json , The other parts of the json i have the objects and they are ok only the saleInfo has issues as the field are changing sometimes it has Listprice and sometimes not, SO i want a builder class that will only create it if needed.
{
"kind": "books#volume",
"id": "UEdjAgAAQBAJ",
"etag": "/KAuiIWJuB4",
"selfLink": "https://www.googleapis.com/books/v1/volumes/UEdjAgAAQBAJ",
"volumeInfo": {
"title": "Java. Podstawy. Wydanie IX",
"authors": [
"Cay S. Horstmann",
"Gary Cornell"
],
"publisher": "Helion",
"publishedDate": "2013-12-09",
"description": "Kolejne wydanie tej cenionej książki zostało zaktualizowane o wszystkie nowości, które pojawiły się w wersji 7 platformy Java Standard Edition. W trakcie lektury poznasz składnię języka oraz wszystkie istotne kwestie związane z programowaniem w Javie. Zrozumiesz założenia programowania obiektowego, nauczysz się korzystać z interfejsów oraz obsługiwać wyjątki. Przekonasz się również, jakie ułatwienia w tym zakresie oferuje Java 7 obsługa wielu wyjątków w ramach jednego bloku catch to tylko czubek góry lodowej.",
"industryIdentifiers": [
{
"type": "ISBN_13",
"identifier": "9788324677610"
},
{
"type": "ISBN_10",
"identifier": "8324677615"
}
],
"readingModes": {
"text": true,
"image": true
},
"pageCount": 864,
"printType": "BOOK",
"categories": [
"Computers"
],
"maturityRating": "NOT_MATURE",
"allowAnonLogging": true,
"contentVersion": "2.5.4.0.preview.3",
"imageLinks": {
"smallThumbnail": "http://books.google.com/books/content?id=UEdjAgAAQBAJ&printsec=frontcover&img=1&zoom=5&edge=curl&source=gbs_api",
"thumbnail": "http://books.google.com/books/content?id=UEdjAgAAQBAJ&printsec=frontcover&img=1&zoom=1&edge=curl&source=gbs_api"
},
"language": "pl",
"previewLink": "http://books.google.pl/books?id=UEdjAgAAQBAJ&pg=PA852&dq=java&hl=&cd=4&source=gbs_api",
"infoLink": "https://play.google.com/store/books/details?id=UEdjAgAAQBAJ&source=gbs_api",
"canonicalVolumeLink": "https://market.android.com/details?id=book-UEdjAgAAQBAJ"
},
"saleInfo": {
"country": "PL",
"saleability": "FOR_SALE",
"isEbook": true,
"listPrice": {
"amount": 79.0,
"currencyCode": "PLN"
},
"retailPrice": {
"amount": 55.3,
"currencyCode": "PLN"
},
"buyLink": "https://play.google.com/store/books/details?id=UEdjAgAAQBAJ&rdid=book-UEdjAgAAQBAJ&rdot=1&source=gbs_api",
"offers": [
{
"finskyOfferType": 1,
"listPrice": {
"amountInMicros": 7.9E7,
"currencyCode": "PLN"
},
"retailPrice": {
"amountInMicros": 5.53E7,
"currencyCode": "PLN"
}
}
]
},
"accessInfo": {
"country": "PL",
"viewability": "PARTIAL",
"embeddable": true,
"publicDomain": false,
"textToSpeechPermission": "ALLOWED",
"epub": {
"isAvailable": true,
"acsTokenLink": "http://books.google.pl/books/download/Java_Podstawy_Wydanie_IX-sample-epub.acsm?id=UEdjAgAAQBAJ&format=epub&output=acs4_fulfillment_token&dl_type=sample&source=gbs_api"
},
"pdf": {
"isAvailable": true,
"acsTokenLink": "http://books.google.pl/books/download/Java_Podstawy_Wydanie_IX-sample-pdf.acsm?id=UEdjAgAAQBAJ&format=pdf&output=acs4_fulfillment_token&dl_type=sample&source=gbs_api"
},
"webReaderLink": "http://play.google.com/books/reader?id=UEdjAgAAQBAJ&hl=&printsec=frontcover&source=gbs_api",
"accessViewStatus": "SAMPLE",
"quoteSharingAllowed": false
},
"searchInfo": {
"textSnippet": "MF, 512 manifestu klasa główna, 514 sekcja główna, 512 wstawianie sekcji, 518 \u003cbr\u003e\nzmienianie zawartości, 513 MapTest.\u003cb\u003ejava\u003c/b\u003e,699 MenuFrame.\u003cb\u003ejava\u003c/b\u003e, 442 \u003cbr\u003e\nMethodTableTest.\u003cb\u003ejava\u003c/b\u003e,266 MouseComponent.\u003cb\u003ejava\u003c/b\u003e, 383 MouseFrame.\u003cb\u003ejava\u003c/b\u003e, 383 \u003cbr\u003e\nNotHelloWorld.\u003cb\u003ejava\u003c/b\u003e, 330, 534 ObjectAnalyzerTest.\u003cb\u003ejava\u003c/b\u003e,259 OptionDialogFrame.\u003cbr\u003e\n\u003cb\u003ejava\u003c/b\u003e,477 overview.html, 194 PackageTest.\u003cb\u003ejava\u003c/b\u003e, 184 PairTest1.\u003cb\u003ejava\u003c/b\u003e, 631 \u003cbr\u003e\nPairTest2.\u003cb\u003ejava\u003c/b\u003e, 634 PairTest3.\u003cb\u003ejava\u003c/b\u003e, 656 ParamTest.\u003cb\u003ejava\u003c/b\u003e, 169 PasswordChooser.\u003cbr\u003e\n\u003cb\u003ejava\u003c/b\u003e, 492 Person.\u003cb\u003ejava\u003c/b\u003e ..."
}
},

It seems like you are missing a constructor with the #JsonCreator tag and the #JsonProperty tags on the parameters.
I am working on a project right now where I use this in a jax-rs context.
Looking into it, it seems like Jackson might not actually use the required property though.
#Builder
#Getter
#Setter
#Value
#RequiredArgsConstructor
#JsonDeserialize()
#JsonInclude(JsonInclude.Include.NON_NULL)
#JsonIgnoreProperties(ignoreUnknown = true)
public class SaleInfo {
private String country;
private String saleability; //This
private boolean isEbook; //THis
// created only if required
private String buyLink;
//TODO i want to have a conditional creation of this two objects below.
ListPrice listPrice;
RetailPrice retailPrice;
#JsonCreator
public SaleInfo(
#JsonProperty("country") String country;
#JsonProperty("saleability") String saleability;
#JsonProperty("isEbook") boolean isEbook;
#JsonProperty(value = "buyLink", required = false) String buyLink;
#JsonProperty(value = "listPrice", required = false) ListPrice listPrice;
#JsonProperty(value = "retailPrice", required = false) RetailPrice retailPrice;
) {
this.country = country;
this.saleability = saleability;
this.isEbook = isEbook;
this.buyLink = buyLink;
this.listPrice = listPrice;
this.retailPrice = country;
}
#Override
public boolean equals(Object o) {
return EqualsBuilder.reflectionEquals(this, o);
}
#Override
public int hashCode() {
return HashCodeBuilder.reflectionHashCode(this);
}
#Override
public String toString() {
return ReflectionToStringBuilder.toString(this);
}

JSON Array of objects to plain old java object

this is my first time making an external api call in Java, so please bear with me as I'm not very experienced. I got the http request working and got a response, but now I need to parse it.
I'm trying to convert a json array to java objects. I understand the gist of it, but all examples I've seen don't apply to my issue.
I need the 'entities' objects from the json string. The details (which are an array, too) can contain any key/value pair, so I was thinking of putting that in a hashmap in each Entity object. I've tried the gson library, but I can't find any gson example that goes deeper than a single dimensional json array.
I realize this is kind of a broad question, and I don't expect anyone to deliver me a working solution, but a few tips or a link to a relevant guide would go a long way. :)
{
"return": {
"entities": [
{
"id": 2385,
"details": [
{
"name": "Other Known Name",
"value": "John Wick",
"match": false
}
],
"proofs": [],
"link": "http://domain.gg/users?id=2385"
},
{
"id": 2384,
"details": [
{
"name": "Discord ID",
"value": "159985870458322944",
"match": false
},
{
"name": "SteamID64",
"value": "76561197991558078",
"match": true
},
{
"name": "SteamVanity",
"value": "test",
"match": false
},
{
"name": "PS4",
"value": "John_S",
"match": false
},
{
"name": "XBox",
"value": "John S",
"match": false
},
{
"name": "Email",
"value": "john_smith#gmail.com",
"match": true
},
{
"name": "Comment",
"value": "Test user",
"match": false
},
{
"name": "Other Known Name",
"value": "Jonathan",
"match": false
},
{
"name": "Reddit",
"value": "/u/johns",
"match": true
}
],
"proofs": [],
"link": "http://domain.gg/users?id=2384"
},
{
"id": 1680,
"details": [
{
"name": "Other Known Name",
"value": "Johny",
"match": false
},
{
"name": "SteamID64",
"value": "76561198213003675",
"match": true
}
],
"proofs": [],
"link": "http://domain.gg/users?id=1680"
},
{
"id": 1689,
"details": [
{
"name": "Other Known Name",
"value": "JohnnyPeto",
"match": false
},
{
"name": "SteamID64",
"value": "76561198094228192",
"match": true
}
],
"proofs": [],
"link": "http://domain.gg/users?id=1689"
}
],
"notice": "Showing 4 out of 4 matches."
}
}

There are many json serialization/deserialization frameworks available. I would recommend having a look at Jackson.
Basically, you have to create Model corresponding to json schema and deserialize json into object. Based on the example in the question, model will look like this:
#JsonIgnoreProperties(ignoreUnknown = true)
class Response {
#JsonProperty("return")
private ResponseObject responseObject;
public ResponseObject getResponseObject() {
return responseObject;
}
public void setResponseObject(ResponseObject responseObject) {
this.responseObject = responseObject;
}
}
#JsonIgnoreProperties(ignoreUnknown = true)
class ResponseObject {
private List<Entity> entities;
public List<Entity> getEntities() {
return entities;
}
public void setEntities(List<Entity> entities) {
this.entities = entities;
}
}
#JsonIgnoreProperties(ignoreUnknown = true)
class Entity {
private String id;
private List<Details> details;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public List<Details> getDetails() {
return details;
}
public void setDetails(List<Details> details) {
this.details = details;
}
}
#JsonIgnoreProperties(ignoreUnknown = true)
class Details {
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
Once the model is defined, you can use ObjectMapper class to perform serialization/deserialization, e.g.:
ObjectMapper mapper = new ObjectMapper();
Response response = mapper.readValue("{\"return\": {\"entities\": [{\"id\": 2385,\"details\": [{\"name\": \"Other Known Name\",\"value\": \"John Wick\",\"match\": false}],\"proofs\": [],\"link\": \"http://domain.gg/users?id=2385\"},{\"id\": 2384,\"details\": [{\"name\": \"Discord ID\",\"value\": \"159985870458322944\",\"match\": false},{\"name\": \"SteamID64\",\"value\": \"76561197991558078\",\"match\": true},{\"name\": \"SteamVanity\",\"value\": \"test\",\"match\": false},{\"name\": \"PS4\",\"value\": \"John_S\",\"match\": false},{\"name\": \"XBox\",\"value\": \"John S\",\"match\": false},{\"name\": \"Email\",\"value\": \"john_smith#gmail.com\",\"match\": true},{\"name\": \"Comment\",\"value\": \"Test user\",\"match\": false},{\"name\": \"Other Known Name\",\"value\": \"Jonathan\",\"match\": false},{\"name\": \"Reddit\",\"value\": \"/u/johns\",\"match\": true}],\"proofs\": [],\"link\": \"http://domain.gg/users?id=2384\"},{\"id\": 1680,\"details\": [{\"name\": \"Other Known Name\",\"value\": \"Johny\",\"match\": false},{\"name\": \"SteamID64\",\"value\": \"76561198213003675\",\"match\": true}],\"proofs\": [],\"link\": \"http://domain.gg/users?id=1680\"},{\"id\": 1689,\"details\": [{\"name\": \"Other Known Name\",\"value\": \"JohnnyPeto\",\"match\": false},{\"name\": \"SteamID64\",\"value\": \"76561198094228192\",\"match\": true}],\"proofs\": [],\"link\": \"http://domain.gg/users?id=1689\"}],\"notice\": \"Showing 4 out of 4 matches.\"}}", Response.class);
System.out.println(response.getResponseObject().getEntities().get(0).getId());
Here's the Javadoc.

If I were you, I'd use Jackson, not GSON. It's specialized on JavaBeans-style mapping. Write classes like this:
public class Detail{
private String name;
private String value;
private boolean match;
// + getters / setters
}
public class Entity{
private int id;
private List<Detail> details;
private String link;
private List<String> proofs;
// you don't have any example data for this, so I'm assuming strings
// + getters / setters
}
public class Result{
private List<Entity> entities;
private String notice;
// + getters / setters
}
and do the conversion with something like
Result result = new ObjectMapper().readValue(json, Result.class);

As my fellow stackoverflow users have previously posted, for this kind of initilization Jackson API would be better. I have however posted the solution for your question with Gson.
I noticed that you like your details to be stored as a HashMap with id as key. However, it seems like this id is actually related to the entities and not to the details.
Disclaimer, I got lazy and used an online POJO generator because I did not want to create objects for all of the Json elements ;) It still showcases how it should be done:
class Main{
public static void main(String[] args) throws FileNotFoundException {
//this is just to load the json file
String input = new Scanner(new File("test.txt")).useDelimiter("\\Z").next();
System.out.println(input);
Gson gson = new Gson();
Example arr = gson.fromJson(input, Example.class);
System.out.println(arr);
}
public class Detail {
#SerializedName("name")
#Expose
public String name;
#SerializedName("value")
#Expose
public String value;
#SerializedName("match")
#Expose
public Boolean match;
#Override
public String toString() {
return "Detail [name=" + name + ", value=" + value + ", match=" + match + "]";
}
}
public class Entity {
#SerializedName("id")
#Expose
public Integer id;
#SerializedName("details")
#Expose
public List<Detail> details = null;
#SerializedName("proofs")
#Expose
public List<Object> proofs = null;
#SerializedName("link")
#Expose
public String link;
#Override
public String toString() {
return "Entity [id=" + id + ", details=" + details + ", proofs=" + proofs + ", link=" + link + "]";
}
}
public class Example {
#SerializedName("return")
#Expose
public Return _return;
#Override
public String toString() {
return "Example [_return=" + _return + "]";
}
}
public class Return {
#SerializedName("entities")
#Expose
public List<Entity> entities = null;
#SerializedName("notice")
#Expose
public String notice;
#Override
public String toString() {
return "Return [entities=" + entities + ", notice=" + notice + "]";
}
}
}
Output
Example [_return=Return [entities=[Entity [id=2385, details=[Detail [name=Other Known Name, value=John Wick, match=false]], proofs=[], link=http://domain.gg/users?id=2385], Entity [id=2384, details=[Detail [name=Discord ID, value=159985870458322944, match=false], Detail [name=SteamID64, value=76561197991558078, match=true], Detail [name=SteamVanity, value=test, match=false], Detail [name=PS4, value=John_S, match=false], Detail [name=XBox, value=John S, match=false], Detail [name=Email, value=john_smith#gmail.com, match=true], Detail [name=Comment, value=Test user, match=false], Detail [name=Other Known Name, value=Jonathan, match=false], Detail [name=Reddit, value=/u/johns, match=true]], proofs=[], link=http://domain.gg/users?id=2384], Entity [id=1680, details=[Detail [name=Other Known Name, value=Johny, match=false], Detail [name=SteamID64, value=76561198213003675, match=true]], proofs=[], link=http://domain.gg/users?id=1680], Entity [id=1689, details=[Detail [name=Other Known Name, value=JohnnyPeto, match=false], Detail [name=SteamID64, value=76561198094228192, match=true]], proofs=[], link=http://domain.gg/users?id=1689]], notice=Showing 4 out of 4 matches.]]

Despite there are answers suggesting you to use Jackson, you can still accomplish easily with Gson with its default configuration just creating proper relations between mappings:
// A generic response, parameterized with <T>, can hold any type except of primitives
final class Response<T> {
#SerializedName("return")
final T ret = null;
}
final class EntitiesAndNotice {
final List<Entity> entities = null;
final String notice = null;
}
final class Entity {
// Unlike Object and any its subclasses, `int` being a primitive cannot be nulled
// Simple 0 won't work either, because the compiler will inline it
// So it's a sort of cheating javac to return a value that holds 0 already
final int id = Integer.valueOf(0);
final List<Detail> details = null;
// Your JSON document does not provide enough info on the elements type
// So it depends on how Gson parses JSON tokens
final List<Object> proofs = null;
final URL link = null;
}
final class Detail {
final String name = null;
final String value = null;
// The same for primitive booleans, or Boolean.FALSE
final boolean match = Boolean.valueOf(false);
}
Example use:
private static final String JSON = "{\"return\":{\"entities\":[{\"id\":2385,\"details\":[{\"name\":\"Other Known Name\",\"value\":\"John Wick\",\"match\":false}],\"proofs\":[],\"link\":\"http://domain.gg/users?id=2385\"},{\"id\":2384,\"details\":[{\"name\":\"Discord ID\",\"value\":\"159985870458322944\",\"match\":false},{\"name\":\"SteamID64\",\"value\":\"76561197991558078\",\"match\":true},{\"name\":\"SteamVanity\",\"value\":\"test\",\"match\":false},{\"name\":\"PS4\",\"value\":\"John_S\",\"match\":false},{\"name\":\"XBox\",\"value\":\"John S\",\"match\":false},{\"name\":\"Email\",\"value\":\"john_smith#gmail.com\",\"match\":true},{\"name\":\"Comment\",\"value\":\"Test user\",\"match\":false},{\"name\":\"Other Known Name\",\"value\":\"Jonathan\",\"match\":false},{\"name\":\"Reddit\",\"value\":\"/u/johns\",\"match\":true}],\"proofs\":[],\"link\":\"http://domain.gg/users?id=2384\"},{\"id\":1680,\"details\":[{\"name\":\"Other Known Name\",\"value\":\"Johny\",\"match\":false},{\"name\":\"SteamID64\",\"value\":\"76561198213003675\",\"match\":true}],\"proofs\":[],\"link\":\"http://domain.gg/users?id=1680\"},{\"id\":1689,\"details\":[{\"name\":\"Other Known Name\",\"value\":\"JohnnyPeto\",\"match\":false},{\"name\":\"SteamID64\",\"value\":\"76561198094228192\",\"match\":true}],\"proofs\":[],\"link\":\"http://domain.gg/users?id=1689\"}],\"notice\":\"Showing 4 out of 4 matches.\"}}";
private static final Gson gson = new Gson();
private static final TypeToken<Response<EntitiesAndNotice>> responseTypeToken = new TypeToken<Response<EntitiesAndNotice>>() {
};
public static void main(final String... args) {
final Response<EntitiesAndNotice> response = gson.fromJson(JSON, responseTypeToken.getType());
final String value = response.ret.entities.get(1).details.get(3).value;
System.out.println(value);
}
Output:
John_S

Mapping JSON String to a POJO with Jackson gives null values

I am trying to read some values under "properties" of following JSON string to a POJO. But all I get is null values.
{
"type": "Feature",
"geometry": {
"type": "Point",
"coordinates": [
144.9798,
-37.743
]
},
"properties": {
"PFI": "51351644",
"EZI_ADD": "581 BELL STREET COBURG 3058",
"ROAD_NAME": "BELL",
"ROAD_TYPE": "STREET",
"LOCALITY": "COBURG",
"LGA_CODE": "316",
"STATE": "VIC",
"POSTCODE": "3058",
"ADD_CLASS": "S"
},
"id": "ADDRESS.581"
}
My POJO class
#JsonIgnoreProperties(ignoreUnknown = true)
class Property {
public Property(){}
private String EZI_ADD; // e.g., "14 FAIRWAY COURT BUNDOORA 3083"
private String STATE; // e.g., "VIC"
private String POSTCODE; // e.g., "3083"
private String LGA_CODE; // e.g., 373
private String LOCALITY; // e.g., "BUNDOORA"
private String ADD_CLASS; // e.g., "S", or "M"
private String SA1_7DIG11 = ""; // SA1 code e.g., "2120241"
public String getEZI_ADD() {
return EZI_ADD;
}
#JsonProperty("EZI_ADD")
public void setEZI_ADD(String eZI_ADD) {
EZI_ADD = eZI_ADD;
}
public String getSTATE() {
return STATE;
}
#JsonProperty("STATE")
public void setSTATE(String sTATE) {
STATE = sTATE;
}
public String getPOSTCODE() {
return POSTCODE;
}
#JsonProperty("POSTCODE")
public void setPOSTCODE(String pOSTCODE) {
POSTCODE = pOSTCODE;
}
public String getLGA_CODE() {
return LGA_CODE;
}
#JsonProperty("LGA_CODE")
public void setLGA_CODE(String lGA_CODE) {
LGA_CODE = lGA_CODE;
}
public String getLOCALITY() {
return LOCALITY;
}
#JsonProperty("LOCALITY")
public void setLOCALITY(String lOCALITY) {
LOCALITY = lOCALITY;
}
public String getADD_CLASS() {
return ADD_CLASS;
}
#JsonProperty("ADD_CLASS")
public void setADD_CLASS(String aDD_CLASS) {
ADD_CLASS = aDD_CLASS;
}
public String getSA1_7DIG11() {
return SA1_7DIG11;
}
#JsonProperty("SA1_7DIG11")
public void setSA1_7DIG11(String sA1_7DIG11) {
SA1_7DIG11 = sA1_7DIG11;
}
}
Conversion code is as follows
//Above json string
String jsonString = "{\"type\":\"Feature\",\"geometry\":{\"type\":\"Point\",\"coordinates\":[144.9798,-37.743]},\"properties\":{\"PFI\":\"51351644\",\"EZI_ADD\":\"581 BELL STREET COBURG 3058\",\"ROAD_NAME\":\"BELL\",\"ROAD_TYPE\":\"STREET\",\"LOCALITY\":\"COBURG\",\"LGA_CODE\":\"316\",\"STATE\":\"VIC\",\"POSTCODE\":\"3058\",\"ADD_CLASS\":\"S\"},\"id\":\"ADDRESS.581\"}";
ObjectMapper mapper = new ObjectMapper();
Property properties = mapper.readValue(jsonString, Property.class);
Output:
{
"properties": {
"EZI_ADD": null,
"STATE": null,
"POSTCODE": null,
"LGA_CODE": null,
"LOCALITY": null,
"ADD_CLASS": null,
"SA1_7DIG11": ""
}
}

The JSON String you're sending does not match the Property class. Add a wrapper class, e.g. something like this:
public class Feature {
private String type;
private String id;
private Property property;
// getters and setters
}
Then you can send the request and the JSON String will be parsed to your object:
{
"type": "feature",
"id": "test",
"property": {
"PFI": "51351644",
"EZI_ADD": "581 BELL STREET COBURG 3058",
"ROAD_NAME": "BELL",
"ROAD_TYPE": "STREET",
"LOCALITY": "COBURG",
"LGA_CODE": "316",
"STATE": "VIC",
"POSTCODE": "3058",
"ADD_CLASS": "S"
}
}

How to convert JSON objects to POJO from Gson

I am trying to convert JSON objects to POJO's with GSON.
JSON String
[
{
"automation_project": {
"user_id": null,
"name": "Untitled Project",
"updated_at": "2015-06-16T19:39:42Z",
"group_id": 764496,
"created_at": "2014-11-23T01:01:59Z",
"id": 16214
}
},
{
"automation_project": {
"user_id": null,
"name": "newintropage",
"updated_at": "2015-06-16T21:20:47Z",
"group_id": 764496,
"created_at": "2015-06-16T20:39:04Z",
"id": 29501
}
}
]
The AutomationProjectsList class used with GSON
public class AutomationProjectsList {
private List<AutomationProject> automationProject = new ArrayList<AutomationProject>();
public List<AutomationProject> getAutomationProject() {
return automationProject;
}
public void setAutomationProject(List<AutomationProject> automationProject) {
this.automationProject = automationProject;
}
#Override
public String toString() {
return "AutomationProjectsList [automationProject=" + automationProject
+ "]";
}}
Automation Project POJO
public class AutomationProject {
private Object userId;
private Integer groupId;
private Integer id;
private String name;
private String updatedAt;
private String createdAt;
public Object getUserId() {
return userId;
}
public void setUserId(Object userId) {
this.userId = userId;
}
public Integer getGroupId() {
return groupId;
}
public void setGroupId(Integer groupId) {
this.groupId = groupId;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getUpdatedAt() {
return updatedAt;
}
public void setUpdatedAt(String updatedAt) {
this.updatedAt = updatedAt;
}
public String getCreatedAt() {
return createdAt;
}
public void setCreatedAt(String createdAt) {
this.createdAt = createdAt;
}}
The code I'm using
JSONArray jsonArray = new JSONArray(response.getEntity(String.class));
for(int i = 0; i < jsonArray.length(); i++){
if(jsonArray.get(i) instanceof JSONObject){
JSONObject jsnObj = (JSONObject)jsonArray.get(i);
AutomationProjectsList obj = new Gson().fromJson(jsnObj.toString(), AutomationProjectsList.class);
System.out.println(obj.getAutomationProject().get(0).getId());
}
}
But it gives an exception :
Exception in thread "main" java.lang.IndexOutOfBoundsException: Index: 0, Size: 0
at java.util.ArrayList.rangeCheck(ArrayList.java:653)
at java.util.ArrayList.get(ArrayList.java:429)
at br.usp.icmc.teste.ConnectionRestClient.getBrowserStackProjects(ConnectionRestClient.java:74)
at br.usp.icmc.teste.TestePrincipal.main(TestePrincipal.java:9)
Why am I receiving an IndexOutOfBoundsException exception? Where am I wrong?

Your class or your JSON are incorrect. I'd suggest your JSON is.
A JSON matching your POJO class would be:
{
"automationProjects":[
{
"user_id": null,
"name": "Untitled Project",
"updated_at": "2015-06-16T19:39:42Z",
"group_id": 764496,
"created_at": "2014-11-23T01:01:59Z",
"id": 16214
},
{
"user_id": null,
"name": "newintropage",
"updated_at": "2015-06-16T21:20:47Z",
"group_id": 764496,
"created_at": "2015-06-16T20:39:04Z",
"id": 29501
}
]
}
Notice I used the name automationProjects for the list as it makes more sense, so your class would be:
public class AutomationProjectsList {
private List<AutomationProject> automationProjects = new ArrayList<AutomationProject>();
public List<AutomationProject> getAutomationProjects() {
return automationProjects;
}
public void setAutomationProjects(List<AutomationProject> automationProjects) {
this.automationProjects = automationProjects;
}
#Override
public String toString() {
return "AutomationProjectsList [automationProject=" + automationProject
+ "]";
}
}
And finally to convert JSON to AutomationProjectsList object:
AutomationProjectsList projectsList = new Gson().fromJson(jsonArray.toString(), AutomationProjectsList.class);
Then if you want to log each project:
for(AutomationProject project : projectsList.automationProjects){
System.out.println(porject.getId());
}
In conclusion, your code seems to have the fallowing issues:
Do you have a list of lists or just a single list of projects? If the list is just one, why do you iterate jsonArray like its sub-objects are lists themselves?
If you model your class correctly on the JSON then you don't need to iterate the JSON to obtain your objects
The JSON you posted is quite weird and uneasy to use with Gson, is it a requirement or can you edit it as you please?
Hope this helps
EDIT
Since you stated you cannot change the JSON you get, then it gets a little more complex, but everything is up to modelling the classes on the JSON format. So let's start form this JSON:
[
{
"automation_project": {
"user_id": null,
"name": "Untitled Project",
"updated_at": "2015-06-16T19:39:42Z",
"group_id": 764496,
"created_at": "2014-11-23T01:01:59Z",
"id": 16214
}
},
{
"automation_project": {
"user_id": null,
"name": "newintropage",
"updated_at": "2015-06-16T21:20:47Z",
"group_id": 764496,
"created_at": "2015-06-16T20:39:04Z",
"id": 29501
}
}
]
Now, this is quite nasty, but let's see what we have here: we have an unnamed array of objects with a single attribute "automationProject" which is our actual AutomationProject Object. So in terms of structure, it is a list of objects which wrap an actual AutomationProject.
Thus you'll need to get rid of your AutomationProjectList and change it with the more meaningful AutomationProjectWrapper looking as fallows:
public class AutomationProjectsWrapper {
private AutomationProject automation_project = new AutomationProject();
public AutomationProject getAutomationProject() {
return automation_project;
}
public void setAutomationProject(AutomationProject automationProject) {
this.automation_project = automationProject;
}
#Override
public String toString() {
return "AutomationProjectsList [automationProject=" + automation_project
+ "]";
}
}
See this class is equivalent to the JSON Object:
{
"automation_project": {
"user_id": null,
"name": "Untitled Project",
"updated_at": "2015-06-16T19:39:42Z",
"group_id": 764496,
"created_at": "2014-11-23T01:01:59Z",
"id": 16214
}
}
Finally you'll have an array of such wrapper objects as your jsonArray so you can write:
AutomationProjectWrapper[] projectsList = new Gson().fromJson(jsonArray.toString(), AutomationProjectWrapper[].class);
Then to log your objects:
for(AutomationProjectWrapper wrapper : projectsList){
System.out.println(wrapper.getAutomationProject().getId());
}
EDIT 2
Sorry for the mistake, in AutomationProjectWrapper class the AutomationProject field should be named automation_project.
Fixed in code above.

According to your JSON String the value you are trying to access is :
jsonString[i].automation_project.user_id
In your code you have: obj.getAutomationProject().get(0).getId()
I think is should be: obj[i].getAutomationProject().getId()

Gson calls returns empty objects over multiple classes

I'm trying to serialize to serialize the json string I have included below.
{
"mood": {
"is_featured": true,
"description": null,
"title": "2014 ",
"ordering": null,
"is_recently_modified": true,
"is_test": false,
"tracks": [
{
"album": {
"release_date": "2014-11-06",
"id": 359778,
"name": "Amansız Gücenik"
},
"name": "Hırpalandı Mayıs",
"artist": {
"id": 491169,
"name": "Ceylan Ertem"
},
"duration": 227,
"isrc": "TRA161400207",
"id": 3903997
},
{
"album": {
"release_date": "2013-08-05",
"id": 329129,
"name": "For Fuld Musik - 25 Danske Sommer Pop & Rock Hits Vol. 2"
},
"name": "Am I Wrong",
"artist": {
"id": 755957,
"name": "Nico & Vinz"
},
"duration": 387,
"isrc": "NO2G31301011",
"id": 3655085
}
],
"image_url": "some_url",
"is_recently_created": true,
"id": 128
}
}
I'm using this gson call to serialize it
Mood mood = new Gson().fromJson(result, Mood.class);
My class structers are like this.
public class Mood {
private boolean is_featured;
private boolean is_recently_modified;
private boolean is_recently_created;
private boolean is_test;
private String description;
private String title;
private String image_url;
private int id;
private int ordering;
private Track[] tracks;
public static class MoodContainer {
public Mood[] moods;
}
}
public class Track {
//variables
private Album album;
private Artist artist;
private Provider provider;
private String secure_url;
private String name;
private String region;
private String isrc;
private int duration;
private int track_order;
private int id;
}
And it goes on like this for any additional class variable. When I try to use the above call I end up with objects that have all null values. One thing to notice is some fields are not supplied in json string because different api calls supply different parts of these json strings. What I am doing wrong?

Root JSON object you provided has property mood - so you either have two options for deserialization to work properly:
Wrap your Mood class inside another object like this:
public class MoodWrapper { private Mood mood; }
and change de-serialization code to
MoodWrapper moodWrapper = new Gson().fromJson(result, MoodWrapper.class);
Skip a root object when deserializing:
final Gson gson = new Gson();
JsonParser parser = new JsonParser();
JsonObject rootObj = parser.parse(json).getAsJsonObject();
Mood mood = gson.fromJson(rootObj.getAsJsonObject("mood"), Mood.class);

The top-level elements in the JSON string should be your object's properties, not the outer element "mood" which you have.